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  • Escherichia coli  (33)
  • Springer  (33)
  • American Chemical Society
  • Cambridge University Press
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2015-2019
  • 2005-2009
  • 1985-1989  (33)
  • 1980-1984
  • 1989  (33)
Collection
Keywords
Publisher
Years
  • 2015-2019
  • 2005-2009
  • 1985-1989  (33)
  • 1980-1984
Year
  • 1
    Electronic Resource
    Electronic Resource
    Thermal inducible expression of xylose isomerase and its performance in a hollow fiber bioreactor (1989)
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 1-5 
    Details
    ISSN: 1476-5535
    Keywords: Xylose isomerase ; Enzyme expression ; thermally inducible ; Hollow fiber bioreactor ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary TheEscherichia coli xylose isomerase (EC 5.3.1.5) has been expressed under the control of a thermal inverting promotor system (att-nutL-p-att-N block) and its performance in a hollow fiber bioreactor measured. The conversion of xylose to xylulose was inversely proportional to the flow rate and the system operated up to 60°C. The maximum conversion efficiency observed was 19.05% at 55°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569686
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and some properties of lysineN 6-hydroxylase fromEscherichia coli strain EN222 (1989)
    Springer
    BioMetals 2 (1989), S. 1-5 
    Details
    ISSN: 1572-8773
    Keywords: LysineN 6-hydroxylase ; External flavoprotein (FAD) monooxygenase ; Aerobactin ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Lysine N6-hydroxylase was isolated as a soluble enzyme from the supernatant after ultrasonication ofEscherichia coli strain EN222 which contained the structural gene on a multicopy plasmid (as described by Engelbrecht and Braun in 1986). The apoenzyme prepared by dialysis was purified by ammonium sulfate precipitation and fast protein liquid chromatography using Superose 12 and Mono Q columns. The molecular mass as determined by gel filtration was 200 kDa and 50 kDa by SDS/polyacrylamide gel electrophoresis. The enzyme binds 0.79 molecule FAD/50 kDa. The activity of the enzyme is strictly dependent on NADPH. Its properties are similar to other flavoprotein monooxygenases of the EC group 1.14.13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01116193
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  • 3
    Electronic Resource
    Electronic Resource
    Electrophoretic and immunological comparisons of chloroplast and prokaryotic ribosomal proteins reveal that certain families of large subunit proteins are evolutionarily conserved (1989)
    Springer
    Journal of molecular evolution 29 (1989), S. 68-88 
    Details
    ISSN: 1432-1432
    Keywords: Ribsomal proteins ; Chloroplast ; Two-dimensional gel electrophoresis ; Immunological cross-reactivity ; Protein evolution ; Peptidyltransferase ; Anabaena 7120 ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Antibodies to individual chloroplast ribosomal (r-)proteins ofChlamydomonas reinhardtii synthesized in either the chloroplast or the cytoplasm were used to examine the relatedness ofChlamydomonas r-proteins to r-proteins from the spinach (Spinacia oleracea) chloroplast,Escherichia coli, and the cyanobacteriumAnabaena 7120. In addition,35S-labeled chloroplast r-proteins from large and small subunits ofC. reinhardtii were coelectrophoresed on 2-D gels with unlabeled r-proteins from similar subunits of spinach chloroplasts,E. coli, andAnabaena to compare their size and net charge. Comigrating protein pairs were not always immunologically related, whereas immunologically related r-protein pairs often did not comigrate but differed only slightly in charge and molecular weight. In constrast, when35S-labeled chloroplast r-proteins from large and small subunits of a closely related speciesC. smithii were coelectrophoresed with unlabeledC. reinhardtii chloroplast r-proteins, only one pair of proteins from each subunit showed a net displacement in mobility. Analysis of immunoblots of one-dimensional SDS and two-dimensional urea/SDS gels of large and small subunit r-proteins from these species revealed more antigenic conservation among the four species of large subunit r-proteins than small subunit r-proteins.Anabaena r-proteins showed the greatest immunological similarity toC. reinhardtii chloroplast r-proteins. In general, antisera made against chloroplast-synthesized r-proteins inC. reinhardtii showed much higher levels of cross-reactivity with r-proteins fromAnabaena, spinach, andE. coli than did antisera to cytoplasmically synthesized r-proteins. All spinach r-proteins that cross-reacted with antisera to chloroplast-synthesized r-proteins ofC. reinhardtii are known to be made in the chloroplast (Dorne et al. 1984b). FourE. coli r-proteins encoded by the S10 operon (L2, S3, L16, and L23) were found to be conserved immunologically among the four species. Two of the large subunit r-proteins, L2 and L16, are essential for peptidyltransferase activity. The third (L23) and two otherE. coli large subunit r-proteins (L5 and L27) that have immunological equivalents among the four species are functionally related to but not essential for peptidyltransferase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02106183
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  • 4
    Electronic Resource
    Electronic Resource
    Physiological significance and bioenergetic aspects of glucose dehydrogenase (1989)
    Springer
    Antonie van Leeuwenhoek 56 (1989), S. 51-61 
    Details
    ISSN: 1572-9699
    Keywords: glucose dehydrogenase ; bioenergetics ; growth yield ; enzyme regulation ; chemostat culture ; Acinetobacter calcoaceticus ; Klebsiella aerogenes ; Escherichia coli ; Pseudomonas species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The regulation of the PQQ-linked glucose dehydrogenase in different organisms is reviewed. It is concluded that this enzyme functions as an auxiliary energy-generating mechanism, because it is maximally synthesized under conditions of energy stress. It is now definitively established that the oxidation of glucose to gluconate generates metabolically useful energy. The magnitude of the contribution of the oxidation of glucose to gluconate via this enzyme to the growth yield of organisms such asAcinetobacter calcoaceticus is not yet clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00822584
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  • 5
    Electronic Resource
    Electronic Resource
    The nucleotide sequence of the lipo-penicillinase gene of alkalophilic Bacillus sp. strain 170 (1989)
    Springer
    Archives of microbiology 151 (1989), S. 91-94 
    Details
    ISSN: 1432-072X
    Keywords: Alkalophilic Bacillus ; Penicillinase ; β-Lactamase ; Class A enzyme ; Lipoprotein ; Amino acid homology ; Gene cloning ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lipo-penicillinase (LIPEN) gene from an alkalophilic Bacillus sp. strain 170 was cloned in Escherichia coli using the vector pHSG399. A plasmid, pFAP121, was isolated from an ampicillin resistant transformant and the cloned LIPEN gene was found to be in a 2.2 kb DNA fragment. The nucleotide sequence of a 1.9 kb segment encoding the LIPEN was determined. This segment showed an open reading frame which would encode a polypeptide of 310 amino acids. The amino acid sequence of this LIPEN gene product has strong homology with those of the Bacillus cereus β-lactamase III and Bacillus licheniformis penicillinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414419
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  • 6
    Electronic Resource
    Electronic Resource
    Carbonic anhydrase activity in acetate grown Methanosarcina barkeri (1989)
    Springer
    Archives of microbiology 151 (1989), S. 137-142 
    Details
    ISSN: 1432-072X
    Keywords: Carbonic anhydrase ; Acetate metabolism ; Carbon monoxide dehydrogenase ; Methanosarcina barkeri ; Desulfobacter postgatei ; Desulfotomaculum acetoxidans ; Peptostreptococcus productus ; Methanococcus voltae ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell extracts (27000xg supernatant) of acetate grown Methanosarcina barkeri were found to have carbonic anhydrase activity (0.41 U/mg protein), which was lost upon heating or incubation with proteinase K. The activity was inhibited by Diamox (apparent K i=0.5 mM), by azide (apparent K i=1 mM), and by cyanide (apparent K i=0.02 mM). These and other properties indicate that the archaebacterium contains the enzyme carbonic anhydrase (EC 4.2.1.1). Evidence is presented that the protein is probably located in the cytoplasm. Methanol or H2/CO2 grown cells of M. barkeri showed no or only very little carbonic anhydrase activity. After transfer of these cells to acetate medium the activity was “induced” suggesting a function of this enzyme in acetate fermentation to CO2 and CH4. Interestingly, Desulfobacter postgatei and Desulfotomaculum acetoxidans, which oxidize acetate to 2 CO2 with sulfate as electron acceptor, were also found to exhibit carbonic anhydrase activity (0.2 U/mg protein).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414428
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  • 7
    Electronic Resource
    Electronic Resource
    Pyrimidine, purine and nitrogen control of cytosine deaminase synthesis in Escherichia coli K12. Involvement of the glnLG and purR genes in the regulation of codA expression (1989)
    Springer
    Archives of microbiology 152 (1989), S. 115-118 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; codA ; glnLG ; purR ; Gene regulation ; Cytosine deaminase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytosine deaminase, encoded by the codA gene in Escherichia coli catalyzes the deamination of cytosine to uracil and ammonia. Regulation of codA expression was studied by determining the level of cytosine deaminase in E. coli K12 grown in various defined media. Addition of either pyrimidine or purine nucleobases to the growth medium caused repressed enzyme levels, whereas growth on a poor nitrogen source such as proline resulted in derepression of cytosine deaminase synthesis. Derepression of codA expression was induced by starvation for either uracil or cytosine nucleotides. Nitrogen control was found to be mediated by the glnLG gene products, and purine repression required a functional purR gene product. Studies with strains harbouring multiple mutations affecting both pyrimidine, purine and nitrogen control revealed that the overall regulation of cytosine deaminase synthesis by the different metabolites is cumulative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00456087
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of copper concentration in continuous culture on the aa 3-type cytochrome oxidase and respiratory chains of Paracoccus denitrificans (1989)
    Springer
    Archives of microbiology 151 (1989), S. 300-306 
    Details
    ISSN: 1432-072X
    Keywords: Copper-limitation ; Escherichia coli ; Cytochrome oxidases ; Oxygen reduction ; Respiratory chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role(s) of copper in a bacterial cytochrome oxidase of the aa 3-type was investigated by growth of Paracoccus denitrificans NCIB 8944, in batch and steady state continuous culture, in a medium from which the bulk of the copper had been extracted. In a medium containing approximately 0.02 μM copper, cellular copper content, cytochromes a+a 3 and cytochrome a 3 were reduced to 55%, 58% and 33% respectively of control values and there were also less marked decreases in cytochromes c+c 1 (to 85%) and a CO-binding b-type cytochrome, possibly cytochrome o (to 71%). Copper deficiency elicited in reduced minus oxidized difference spectra a shift to shorter wavelengths and narrowing of the band width of the α-band of the oxidase, and loss of a (negative) band near 830 nm attributable to CuA (the copper functionally associated with haem a in the oxidase complex). The oxidase in copper-deficient cells reacted with oxygen to form the oxy “Compound A” at rates similar to that in control cells but CO recombination to ferrous haem a 3 was slowed 4-fold in the copper deficient case. The results are interpreted as indicating loss of CuA and changes in the proportions of haems a and a 3 with retention of catalytic activity. Titrations of respiration rates with antimycin suggested that copper deficiency did not result in diversion of electron flux through an antimycin A-insensitive, cytochrome o-terminated branch of the respiratory chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406555
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  • 9
    Electronic Resource
    Electronic Resource
    The cloned β-mannanase gene from alkalophilic Bacillus sp. AM-001 produces two β-mannanases in Escherichia coli (1989)
    Springer
    Archives of microbiology 152 (1989), S. 10-15 
    Details
    ISSN: 1432-072X
    Keywords: Alkalophilic Bacillus sp. ; β-Mannanase gene ; Escherichia coli ; Cloning ; Expression ; β-Mannanase ; Southern hybridization ; Western blotting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gene encoding β-mannanase was cloned from alkalophilic Bacillus sp. AM-001 into Escherichia coli JM 101 by inserting HindIII-generated DNA fragments into the HindIII site of pUC19. A 2.0 kb XbaI-PstI fragment of the donor strain DNA was sufficient for β-mannanase synthesis. The amount of β-mannanase expressed in E. coli JM101 harboring pMAH3 (containing a 2.4 kb XbaI-HindIII fragment) was about 24% of the activity produced by the donor strain. E. coli JM101 harboring pMAH3 was found to produce two enzymatically active β-mannanases (A and B). These two β-mannanases were purified to electrophoretically homogenous states. The β-mannanase A had enzymatic properties similar to those of the β-mannanases M-I and M-II produced by alkalophilic Bacillus sp. AM-001, and the β-mannanase B resembled its β-mannanase M-III. In contrast to β-mannanase production in the donor strain, that in E. coli was not inducible. The NH2-terminal amino acid sequences from amino acid 1 (Asn) to 9 (Gln) of the three β-mannanases purified from alkalophilic Bacillus sp. AM-001 coincide with those from amino acid 4 (Asn) to 12 (Gln) of the two β-mannanases purified from E. coli transformant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447004
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  • 10
    Electronic Resource
    Electronic Resource
    Changes of Escherichia coli cell cycle parameters during fast growth and throughout growth with limiting amounts of thymine (1989)
    Springer
    Archives of microbiology 152 (1989), S. 578-583 
    Details
    ISSN: 1432-072X
    Keywords: Cell growth ; Cell cycle ; Cell division ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is generally accepted that during fast growth of Escherichia coli, the time (D) between the end of a round of DNA replication and cell division is constant. This concept is not consistent with the fact that average cell mass of a culture is an exponential function of the growth rate, if it is also accepted that average cell mass per origin of DNA replication (Mi) changes with growth rate and negative exponential cell age distribution is taken into account. Data obtained from cell composition analysis of E. coli OV-2 have shown that not only (Mi) but also D varied with growth rate at generation times (τ) between 54 and 30 min. E. coli OV-2 is a thymine auxotroph in which the replication time (C) can be lengthened, without inducing changes in τ, by growth with limiting amounts of thymine. This property has been used to study the relationship between cell size and division from cell composition measurements during growth with different amounts of thymine. When C increased, average cell mass at the end of a round of DNA replication also increased while D decreased, but only the time lapse (d) between the end of a replication round and cell constriction initiation appeared to be affected because the constriction period remained fairly constant. We propose that the rate at which cells proceed to constriction initiation from the end of replication is regulated by cell mass at this event, big cells having shorter d times than small cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425490
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  • 11
    Electronic Resource
    Electronic Resource
    Expression of Anabaena ferredoxin genes in Escherichia coli (1989)
    Springer
    Plant molecular biology 12 (1989), S. 667-672 
    Details
    ISSN: 1573-5028
    Keywords: ferredoxin ; gene expression ; heterocyst ; Anabaena 7120 ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genes for ferredoxin from heterocysts (fdx H) and vegetative cells (pet F) of Anabaena sp. strain 7120 were subcloned into plasmid pUC 18/19. Both genes were expressed in Escherichia coli at high levels (≈10% of total protein). Pet F could be expressed from its own promoter. The ferredoxins were correctly assembled to the holoprotein. Heterocyst ferredoxin was purified from E. coli extracts on a large scale. Its biochemical and biophysical properties were identical to those of the authentic ferredoxin, isolated from Anabaena heterocysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044157
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  • 12
    Electronic Resource
    Electronic Resource
    Voltage-sensitive ion channel ofEscherichia coli (1989)
    Springer
    The journal of membrane biology 112 (1989), S. 267-275 
    Details
    ISSN: 1432-1424
    Keywords: Escherichia coli ; outer membrane ; ion channel ; patch clamp ; porin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A voltage-sensitive, cation-selective ion channel ofEscherichia coli has been reconstituted into liposomes and studied with the patch-clamp method. The single channel conductance was 91 pS in symmetric solutions of 150mm KCl. Many channels were open most of the time, with frequent brief transitions to closed levels. Multiple conducting units could close and reopen simultaneously, and this apparent cooperativity in gating was increases with depolarizing voltages. Above a voltage threshold, the channels closed irreversibly, often in groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870957
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  • 13
    Electronic Resource
    Electronic Resource
    Three rpoBC mutations that suppress the termination defects of rho mutants also affect the functions of nusA mutants (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 269-275 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; RNA polymerase ; Transcription termination and antitermination ; Rho-NusA-RNA polymerase interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have mapped three Escherichia coli RNA polymerase mutations selected by Guarente (1979) to suppress the termination defects of rho201. We find that two of the mutations are located in the 3′ half of the rpoB gene encoding the β subunit. The third mutation is in the rpoC gene, encoding the β′ subunit. All three RNA polymerase mutations affect termination efficiency, even in rho + strains, suggesting that the C-terminal end of the β as well as the β′ subunit participates in termination. In addition we find that all three rpoBC alleles inhibit λ N-mediated antitermination at 30° C in a strain containing the nusA1 allele. It may be significant that the three other RNA polymerase mutations known to revert the termination defect of mutant rho alleles also affect N-mediated antitermination in nusA1 strains. The correlation of these two phenotypes suggests that both phenotypes may arise from the same functional defect in RNA polymerase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334365
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  • 14
    Electronic Resource
    Electronic Resource
    Identification of the recR locus of Escherichia coli K-12 and analysis of its role in recombination and DNA repair (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 503-510 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; recR ; Recombination ; DNA repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new recombination gene called recR has been identified and located near dnaZ at minute 11 on the current linkage map of Escherichia coli. The gene was detected after transposon mutagenesis of a recB sbcB sbcC strain and screening for insertion mutants that had a reduced efficiency of recombination in Hfr crosses. The recR insertions obtained conferred a recombination deficient and extremely UV sensitive phenotype in both recB recC sbcA and recB recC sbcB sbcC genetic backgrounds. recR derivatives of recBC + sbc + strains were proficient in conjugational and transductional recombination but deficient in plasmid recombination and sensitive to UV light. Strains carrying recR insertions combined with mutations uvrA and other rec genes revealed that the gene is involved in a recombinational process of DNA repair that relies also on recF and recO, and possibly recJ, but which is independent of recB, recC and recD. The properties of two other insertions, one located near pyrE and the other near guaA, are discussed in relation to their proximity to recG and xse (the gene for exonuclease VII), respectively.
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    URL: http://dx.doi.org/10.1007/BF00334397
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  • 15
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    Electronic Resource
    Control of formation of active soluble or inactive insoluble baker's yeast α-glucosidase PI in Escherichia coli by induction and growth conditions (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 149-155 
    Details
    ISSN: 1617-4623
    Keywords: α-Glucosidase ; Active expression ; Escherichia coli ; Refractile bodies ; Protein folding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using standard growth conditions (LB medium, 37°C, induction with 5 mM IPTG) yeast α-glucosidase PI expressed under the control of the regulated tac-hybrid promoter results in the synthesis of insoluble aggregated α-glucosidase granules in Escherichia coli. Under these conditions active soluble α-glucosidase amounts to less than 1% of the heterologously produced protein. However, the amount of soluble active α-glucosidase was dramatically increased when the strong tac-hybrid promoter was to a limited extent induced. This was achieved at concentrations of 0.01 mM IPTG or of 1% lactose or lower in a lactosepermease deficient host strain containing the lacI qrepressor gene on an R-plasmid. The formation of active soluble α-glucosidase was almost 100% when E. coli cells induced in this manner were cultivated under conditions that reduced growth rate, i.e. at decreased temperature, extreme pH values or in minimal and complete media supplemented with different carbon sources.
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    URL: http://dx.doi.org/10.1007/BF00332244
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  • 16
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    Modification of length, hydrophobic properties and electric charge of Bacillus subtilis α-amylase signal peptide and their different effects on the production of secretory proteins in B. subtilis and Escherichia coli cells (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 1-9 
    Details
    ISSN: 1617-4623
    Keywords: amyE signal peptide ; Structural modification ; Production of secreted proteins ; Bacillus subtilis ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bacillus subtilis α-amylase signal peptide, which consists of 33 amino acids, is functional in Escherichia coli cells.Lysine, glutamic acid, leucine, leucyl-leucine, or leucyl-leucyl-leucine was inserted between positions 28 and 29 of the α-amylase signal peptide using site directed mutagenesis. DNAs encoding the wild-type and modified signal peptides were then fused in-frame to DNAs encoding the mature regions of the β-lactamase of pBR322 and a thermostable α-amylase. The secretion of β-lactamase in E. coli cells was more inhibited by the modified signal peptides than that in B. subtilis cells, although the degree of inhibition varied and the inhibitory effect of each signal peptide was found to be similar in the two strains. In contrast, the difference in the inhibitory effect of each modified signal peptide was no longer detected in the case of the production of thermostable α-amylase, except for the insertion of glutamic acid. Nearly 50% of thermostable α-amylase in the precursor form was accumulated in the intracellular fraction of E. coli cells containing the DNAs for the modified signal peptides. The insertion of glutamic acid inhibited the secretion of the two enzymes in both B. subtilis and E. coli cells.
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    URL: http://dx.doi.org/10.1007/BF00332223
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  • 17
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    Vitamin B12 transport inEscherichia coli K12 does not require thebtuE gene of thebtuCED operon (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 301-308 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Vitamin B12 ; btuCED ; Transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transport of vitamin B12 across the cytoplamic membrane ofEscherichia coli requires the products ofbtuC andbtuD, two genes in thebtuCED operon. The role ofbtuE, the central gene of this operon, was examined. Deletions withinbtuE were constructed by removal of internal restriction fragments and were crossed onto the chromosome by allelic replacement. In-frame deletions that removed 20% or 82% of thebtuE coding region did not affect expression of the distalbtuD gene. These nonpolar deletions had little effect on vitamin B12 binding (whole cells or periplasmic fraction) and transport. They did not affect the utilization of vitamin B12 or other cobalamins for methionine biosynthesis, even in strains with decreased outer membrane transport of vitamin B12. ThebtuE mutations did not impair adenosyl-cobalamin dependent catabolism of ethanolamine or repression ofbtuB expression. Thus, despite its genetic location in the transport operon, thebtuE product plays no essential role in vitamin B12 transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02464897
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  • 18
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    An Escherichia coli cis-acting antiterminator sequence: The dnaG nut site (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 195-203 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; dnaG nut ; Antitermination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Escherichia coli rpsU-dnaG-rpoD operon contains an internal transcription terminator T1 located in the intergenic region between the rpsU and dnaG genes (Smiley et al. 1982). By cloning T1 as a small 127 bp fragment into the terminator probe plasmid pDR720 between the trp operator promoter and the assayable galK gene, it was shown that T1 acts as a strong transcription terminator, comparable in strength to the 3′ operon terminator T2. However, an operon sequence that occurs 5′ to T1 within the coding region of the rpsU gene and which has homology with the lambda nut site, (Lupski et al. 1983) when placed 5′ to T1 in the pDR720 plasmid construct, modifies transcription through T1 allowing expression of the galK gene. This sequence, called the dnaG nut site also modifies the termination activity of the external operon terminator T2. It is proposed that the dnaG nut site is a cis-acting element of an antitermination system in E. coli.
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    URL: http://dx.doi.org/10.1007/BF00334356
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  • 19
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    The Escherichia coli dam gene is expressed as a distal gene of a new operon (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 85-96 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; DNA replication ; GATC methylation ; dam gene expression ; DnaA sites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary DNA containing the Escherichia coli dam gene and sequences upstream from this gene were cloned from the Clarke-Carbon plasmids pLC29-47 and pLC13-42. Promoter activity was localized using pKO expression vectors and galactokinase assays to two regions, one 1650–2100 bp and the other beyon 2400 bp upstream of the dam gene. No promoter activity was detected immediately in front of this gene; plasmid pDam118, from which the nucleotide sequence of the dam gene was determined, is shown to contain the pBR322 promoter for the primer RNA from the pBR322 rep region present on a 76 bp Sau3A fragment inserted upstream of the dam gene in the correct orientation for dam expression. The nucleotide sequence upstream of dam has been determined. An open reading frame (ORF) is present between the nearest promoter region and the dam gene. Codon usage and base frequency analysis indicate that this is expressed as a protein of predicted size 46 kDa. A protein of size close to 46 kDa is expressed from this region, detected using minicell analysis. No function has been determined for this protein, and no significant homology exist between it and sequences in the PIR protein or GenBank DNA databases. This unidentified reading frame (URF) is termed urf-74.3, since it is an URF located at 74.3 min on the E. coli chromosome. Sequence comparisons between the regions upstream of urf-74.3 and the aroB gene show that the aroB gene is located immediately upstream of urf-74.3, and that the promoter activity nearest to dam is found within the aroB structural gene. This activity is relatively weak (about 15% of that of the E. coli gal operon promoter). The promoter activity detected beyond 2400 bp upstream of dam is likely to be that of the aroB gene, and is 3 to 4 times stronger than that found within the aroB gene. Three potential DnaA binding sites, each with homology of 8 of 9 bp, are present, two in the aroB promoter region and one just upstream of the dam gene. Expression through the site adjacent to the dam gene is enhanced 2-to 4-fold in dnaA mutants at 38°C. Restriction site comparisons map these regions precisely on the Clarke-Carbon plasmids pLC13-42 and pLC29-47, and show that the E. coli ponA (mrcA) gene resides about 6 kb upstream of aroB.
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    URL: http://dx.doi.org/10.1007/BF00330946
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    Characterization of the generimK responsible for the addition of glutamic acid residues to the C-terminus of ribosomal protein S6 inEscherichia coli K12 (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 281-288 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Ribosomal protein S6 ; Addition of glutamic acid residues ; Cloning and sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ribosomal protein S6 of wild-type strains ofEscherichia coli contains up to six glutamic acid residues at its C-terminus. The first two residues are encoded by the structural gene for this protein (rpsF) and the rest are added post-translationally. Mutants deficient in this modification were isolated and characterized genetically and biochemically. The S6 protein in these mutants appeared to contain only two glutamic acid residues at the C-terminus as expected. The mutated gene was termedrimK and was mapped at 18.7 min betweencmlA andaroA. TherimK gene was cloned into a cosmid vector and its nucleotide sequence determined. Analysis of the transcriptional and translational products of this gene indicates that it encodes a protein with an Mr of 31.5 kDa and that it forms an operon with a gene encoding a 24 kDa protein. AnrpsF mutant containing a Glu to Lys replacement in the second residue from the C-terminus of protein S6 was isolated. The S6 protein of this mutant was apparently inaccessible to the RimK modification system. This indicates that the RimK modification system requires the wild-type amino acid sequence at least in the C-terminal region of ribosomal protein S6.
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    URL: http://dx.doi.org/10.1007/BF02464894
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  • 21
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    Genetic requirements for hyper-recombination by very short patch mismatch repair: Involvement ofEscherichia coli DNA polymerase I (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 254-256 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Bacteriophage λ ; DNA polymerase ; AP-endonuclease ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It has been established that very short patch (VSP) mismatch repair, depending inEscherichia coli on MutL, MutS and Dcm functions, is responsible for the hyper-recombinogenic effect of a class of genetic markers. We show that VSP repair requires the presence of the complete DNA polymerase I enzyme. The absence of endonuclease activities involved in the repair of base-loss sites, Nth, Nfo and Xth, does not affect VSP repair. Implications for the mechanism of the VSP repair are discussed.
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    URL: http://dx.doi.org/10.1007/BF02464889
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    Alternative pathways of methyl methanesulfonate-induced mutagenesis in Escherichia coli (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 126-131 
    Details
    ISSN: 1617-4623
    Keywords: Methyl methanesulfonate mismatch repair ; Mutagenesis ; Suppressive mutations ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Methyl methanesulfonate (MMS) induced mutagenesis is known to be largely dependent on functional umuCD and recA genes. By phenotypic analysis of Arg+ (argE3, ochre) revertants according to their reversion of the mutations his-4 (ochre) and thr-1 (amber), we attempted to deduce the specificity and/or sites of MMS-induced mutations. It is shown that: (1) MMS-induced, umuC-dependent Arg+ revertants (which prevail in bacteria proficient in mismatch repair) result from a different mutational pathway from umuC-independent ones. UmuC-dependent Arg+ revertants belong to class 2 (Arg+His+Thr−), and umuC-independent ones to class 1 (Arg+His−Thr−). (2) The mismatch repair system very efficiently prevents mutations induced by MMS. We found that in the mutS strain, deficient in mismatch repair, class 1 Arg+ revertants are the most numerous, whereas class 2 Arg+ revertants occur at similar levels in MMS-treated mutS and mutS + strains. Therefore the mismatch repair system very efficiently prevents formation of umuC-independent Arg+ revertants, but exerts negligible or no effect on umuC-dependent Arg+ revertants. (iii) Both mutS umuC and mutS recA strains, are highly mutable by MMS.
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    URL: http://dx.doi.org/10.1007/BF00332240
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    The role of the carboxy-terminal membrane-spanning fragment in the biogenesis of Escherichia coli K12 outer membrane protein PhoE (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 144-148 
    Details
    ISSN: 1617-4623
    Keywords: PhoE porin ; Outer membrane protein ; Escherichia coli ; Biogenesis-topology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary PhoE protein of Escherichia coli K12 is an outer membrane protein which is supposed to span the membrane sixteen times. By creating a deletion which removes the last membrane-spanning fragment and studying the localization of the truncated PhoE, we show that this fragment is indispensable for trimerization and outer membrane localization. In addition, circumstantial evidence for the proposed topology model of the protein was obtained. An insertion mutation in a region supposed to be cell surface-exposed, interferes with the binding of a monoclonal antibody which recognizes a cell surface-exposed epitope of the protein.
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    URL: http://dx.doi.org/10.1007/BF00332243
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    Isolation and nucleotide sequence of the hemA gene of Escherichia coli K12 (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 347-352 
    Details
    ISSN: 1617-4623
    Keywords: Δ-ALA synthase (Δ-ALAS) ; hemA gene ; Escherichia coli ; Porphyrins ; Heme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hemA gene of Escherichia coli K12 was cloned by complementation of a hemA mutant of this organism. Subcloning of the initial 6.0 kb HindIII fragment allowed the isolation of a 1.5 kb NheI-AvaI fragment which retained the ability to complement the hemA mutant. DNA sequencing by the dideoxy chain terminator method of Sanger showed the presence of an open reading frame (ORF) of 1254 nucleotides, which ends 6 nucleotides beyond the AvaI site. Primer extension experiments showed the existence of a putative transcription initiation site for the hemA gene, located at position 130. A possible promoter sequence was identified upstream from this transcription initiation site, and its functional activity was confirmed by the use of the pK01 promoter-probe vector. Protein synthesis in an in vitro coupled transcription-translation system showed a 46 kDa protein, which corresponds to the mol. wt. of the hemA protein, as deduced from the nucleotide sequence of the gene. No homology was found between the amino acid sequence of the hemA protein of E. coli K12 and known sequences of other Δ-aminolevulinic acid synthases (Δ-ALAS), suggesting that this protein is different from other Δ-ALAS enzymes.
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    URL: http://dx.doi.org/10.1007/BF00334375
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    Iron-hydroxamate transport intoEscherichia coli K12: Localization of FhuD in the periplasm and of FhuB in the cytoplasmic membrane (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 233-239 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Iron-hydroxamate transport ; fhuB, C, D genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary ThefhuB, fhuC andfhuD genes encode proteins which catalyze transport of iron(III)-hydroxamate compounds from the periplasm into the cytoplasm ofEscherichia coli. ThefhuB, C, D genes were cloned downstream of a strong phage T7 promoter and transcribed by T7 RNA polymerase. The overexpressed FhuD protein appeared in two forms of 31 and 28 kDa and was released upon conversion of vegetative cells into spheroplasts, suggesting synthesis of FhuD as a precursor and export into the periplasm. The very hydrophobic FhuB protein was found in the cytoplasmic membrane. These properties, together with the previously found homologies in the FhuC protein to ATP-binding proteins, display the characteristics of a periplasmic binding protein dependent transport system across the cytoplasmic membrane. The molecular weight of FhuB and the sequence offhuC, as previously published by us, was confirmed. FhuB exhibited double the size of most hydrophobic proteins of such systems and showed homology between the amino- and carboxy-terminal halves of the protein, indicating duplication of an original gene and subsequent fusion of the two DNA fragments.
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    URL: http://dx.doi.org/10.1007/BF02464886
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    Cloning and molecular characterization of the generimL wich encodes an enzyme acetylating ribosomal protein L12 ofEscherichia coki K12 (1989)
    Springer
    Molecular genetics and genomics 217 (1989), S. 289-293 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Ribosomal protein L12 ; N-terminal acetylation ; Cloning and sequencing ; Sequence similarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary TherimL gene ofEscherichia coli K12 encodes en enzyme catalyzing the acetylation of the N-terminal serine of ribosomal protein L12, thereby converting it into L7. Using a mutant strain defective in this acetylation reaction, we cloned therimL gene into cosmid pHC79 and characterized it at the molecular level. From analysis by SDS-polyacrylamide gel electrophoresis of the proteins synthesized in maxi-cells containing derivatives of therimL-harboring plasmid into which transposon λδ had been inserted at various sites, the product of this gene was identified as a protein with an apparent molecular weight of 20.3 kDa. The nucleotide sequence of the gene and the amino acid sequence deduced from the nucleotide sequence were compared with those of two other ribosomal protein acetylses encoded by therimI andrimJ genes (Yoshikawa et al. 1987). A considerable degree of overall similarity was seen betweenrimL andrimJ, but the degree of similarity betweenrimL andrimI was very low. In addition, a short stretch of similar amino acid sequence was found in all threerim acetylases. The significance of these results with respect to other acetylating enzymes, in particular those involved in the acetylation of aminoglycoside antibiotics is discussed.
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    URL: http://dx.doi.org/10.1007/BF02464895
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    Identification and DNA sequence of tdcR, a positive regulatory gene of the tdc operon of Escherichia coli (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 516-522 
    Details
    ISSN: 1617-4623
    Keywords: Gene regulation ; tdc operon ; Escherichia coli ; tdc activator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Efficient in vivo expression of the biodegradative threonine dehydratase (tdc) operon of Escherichia coli is dependent on a regulatory gene, tdcR. The tdcR gene is located 198 base pairs upstream of the tdc operon and is transcribed divergently from this operon. The nucleotide sequence of tdcR and two unrelated reading frames has been determined. The deduced amino acid sequence of TdcR indicates that is is a polypeptide of Mr 12000 with 99 amino acid residues and contains a potential helix-turnhelix DNA binding motif. Deletion analysis and minicell expression of the tdcR gene suggest that TdcR may serve as a trans-acting positive activator for the tdc operon.
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    URL: http://dx.doi.org/10.1007/BF00332418
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    Methylation strongly enhances DNA bending in the replication origin region of the Escherichia coli chromosome (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 69-74 
    Details
    ISSN: 1617-4623
    Keywords: DNA curvature ; Dam methylation ; Escherichia coli ; oriC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis, at high and low temperatures, and gel mobilities of circularly permuted DNA segments showed a large bending locus about 50 bp downstream from the right border of the 245 by oriC box, a minimal essential region of autonomous replication on the Escherichia coli chromosome. Bending was strongly enhanced by Dam methylation. In DNA from a Dam− strain, the mobility anomaly arising from altered conformation was much reduced, but was raised to the original level by methylation in vivo or in vitro. Enhancement of the mobility anomaly was also observed by hybrid formation of the Dam− strand with the Dam+ strand. Near the bending center, GATC, the target of Dam methylase, occurs seven times arranged essentially on the same face of the helix with 10.5 by per turn. We concluded that small bends at each Dam site added up to the large bending detectable by gel electrophoresis.
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    URL: http://dx.doi.org/10.1007/BF00261159
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    A regulatory element within a gene of a ribosomal protein operon of Escherichia coli negatively controls expression by decreasing the translational efficiency (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 381-389 
    Details
    ISSN: 1617-4623
    Keywords: Translational regulation ; 21 K protein ; Ribosomal protein operon ; Negative control element ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The trmD operon of Escherichia coli consists of the genes for the ribosomal protein (r-protein) S16, a 21 kDa protein (21K) of unknown function, the tRNA(m1G37)methyltransferase (TrmD), and r-protein L19, in this order. Previously we have shown that the steady-state amount of the two r-proteins exceeds that of the 21K and TrmD proteins 12- and 40-fold, respectively, and that this differential expression is solely explained by translational regulation. Here we have constructed translational gene fusions of the trmD operon and lacZ. The expression of a lacZ fusion containing the first 18 codons of the 21K protein gene is 15-fold higher than the expression of fusions containing 49 or 72 codons of the gene. This suggests that sequences between the 18th and the 49th codon may act as a negative element controlling the expression of the 21K protein gene. Evidence is presented which demonstrates that this regulation is achieved by reducing the efficiency of translation.
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    URL: http://dx.doi.org/10.1007/BF00259610
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    Isolation of a formamidopyrimidine-DNA glycosylase (fpg) mutant of Escherichia coli K12 (1989)
    Springer
    Molecular genetics and genomics 215 (1989), S. 300-305 
    Details
    ISSN: 1617-4623
    Keywords: DNA repair ; Formamidopyrimidine-DNA glycosylase gene ; Enzyme deficient mutant ; Escherichia coli ; Alkylating agents and γ-radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fpg + gene of Escherichia coli coding for formamidopyrimidine-DNA glycosylase was previously cloned on a multicopy plasmid. The plasmid copy of the fpg + gene was inactivated by cloning a kanamycin resistance gene into the open reading frame, yielding the fpg-1:: Knr mutation. This mutation was transferred to the chromosome in the following steps: (i) linearization of the plasmid bearing the fpg-1::Knr mutation and transformation of competent bacteria (recB recC sbcB); (ii) selection for chromosomal integration of the fpg-1::Knr mutation; (iii) phage P1 mediated transduction of the fpg-1::Knr mutation in the AB1157 background. The resulting fpg - mutant exhibited no detectable Fapy-DNA glycosylase activity in crude lysates. The insertion mutation was localized by means of genetic crosses between mtl and pyrE, at 81.7 min on the E. coli linkage map. Sequence analysis confirmed this mapping and further showed that fpg is adjacent to rpmBG in the order fpg, rpmGB, pyrE. The formamidopyrimidine-DNA glycosylase defective strain does not show unusual sensitivity to the following DNA damaging treatments: (i) methylmethanesulfonate, (ii) N-methyl-N′-nitro-N-nitrosoguanidine, (iii) ultraviolet light, (iv) γ-radiation. The fpg gene is neither part of the SOS regulon nor the adaptive response to alkylating agents.
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    URL: http://dx.doi.org/10.1007/BF00339732
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    Initiation of DNA replication in Escherichia coli after overproduction of the DnaA protein (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 50-56 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Initiation of DNA replication ; DnaA protein ; Flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Flow cytometry was used to study initiation of DNA replication in Escherichia coli K12 after induced expression of a plasmid-borne dnaA + gene. When the dnaA gene was induced from either the plac or the λpL promoter initiation was stimulated, as evidenced by an increase in the number of origins and in DNA content per mass unit. During prolonged growth under inducing conditions the origin and DNA content per mass unit were stabilized at levels significantly higher than those found before induction or in similarly treated control cells. The largest increase was observed when using the stronger promoter λpL compared to plac. Synchrony of initiation was reasonably well maintained with elevated DnaA protein concentrations, indicating that simultaneous initiation of all origins was still preferred under these conditions. A reduced rate of replication fork movement was found in the presence of rifampin when the DnaA protein was overproduced. We conclude that increased synthesis levels or increased concentrations of the DnaA protein stimulate initiation of DNA replication. The data suggest that the DnaA protein may be the limiting factor for initiation under normal physiological conditions.
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    URL: http://dx.doi.org/10.1007/BF00330564
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    Thiolutin inhibits utilization of glucose and other carbon sources in cells of Escherichia coli (1989)
    Springer
    Antonie van Leeuwenhoek 55 (1989), S. 143-152 
    Details
    ISSN: 1572-9699
    Keywords: thiolutin ; Escherichia coli ; transport ; respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thiolutin was found to inhibit the utilization of glucose and other growth substrates in Escherichia coli. The inhibition was detected by a sharp drop of the respiration rate after addition of the antibiotic. The actual function affected was allocated to the cytoplasmic membrane of the bacterial cells by the following evidence: - spheroplasts were affected like intact cells, - individual reactions of either the electron transport chain or the glycolytic pathway were not inhibited, - glucose consumption in the culture stopped and the cells accumulated guanosine tetraphosphate as under starvation conditions, - activation of the cell's apo-glucose dehydrogenase restored respiration via bypassing the glucose phosphotransferase system. It was concluded that the transport of certain substrates across the membrane was inhibited.
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    URL: http://dx.doi.org/10.1007/BF00404754
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    The use ofEscherichia coli mutants to measure the bioavailability of essential amino acids in foods (1989)
    Springer
    Plant foods for human nutrition 39 (1989), S. 109-120 
    Details
    ISSN: 1573-9104
    Keywords: microbiological assay ; amino acids ; Escherichia coli ; β-galactosidase ; processed foods ; pronase digests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The β-galactosidase-based assay for lysine developed by Tuffnell & Payne was used to measure the bioavailabilities of cyst(e)ine, methionine, threonine and tryptophan in pronase digests of 17 foods. The digests were assayed by estimating the β-galactosidase synthesis responses of fiveEscherichia coli mutants, each requiring one of the respective amino acids for protein synthesis. Deletion mutants were used whenever possible in order to ensure strain stability. Single digests of each food were assayed with 3 or 4 separate cultures of each mutant and the results were compared with those from the corresponding chemical assay. Omitting the anomalously low values for one food, the rank correlation coefficients of the bio- and chemo-assay values were 0.61 (cysteine), 0.91 (lysine), 0.95 (methionine), 0.64 (threonine) and 0.85 (tryptophan). Mean (± S.D.) relative amino acid bioavailabilities (casein = 100%) for the 17 foods were: cysteine, 53±23; lysine, 90±10; methionine, 95±18; threonine, 89±13; and tryptophan, 89±25. The cysteine mutant appeared to give unusually low bioavailability values except for the milk products. These amino acid mutants afford a rapid method for assaying the bioavailabilities of at least four of the five amino acids studied.
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    URL: http://dx.doi.org/10.1007/BF01092407
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