ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Total DNA from Halobacterium halobium and other halobacteria strains is separated into two fractions, FI and FII, which differ in their G+C content. FI DNA, which represents the major part of the genome is highly conserved in all purple-membrane-forming halobacteria. Fraction II (FII) consists in H. halobium of three DNA specimen: (a) the previously isolated plasmid pHH1, (b) a heterogeneous set of ccc-DNA molecules present in the cell in low copies, termed minor-circular DNA (MCD) and (c) a new type of more A-T rich DNA segments (“chromosomal islands”) which, as described here and by Pfeifer and Betlach (1985), are integrated in FI. Sequences homologous to pHH1 occur only in Halobacterium species closely related to H. halobium (like H. cutirubrum), whereas MCD sequences are present in all purple-membrane-forming halobacteria. The sequences of the newly identified “chromosomal islands” are only found like pHH1, in Halobacterium species, closely related to H. halobium. Total DNA from square halobacteria exhibits no extended homologies to FI or FII DNA from H. halobium. The only common DNA sequences found in all halobacteria are certain insertion elements (ISH), such as ISH26. Based on these data, halobacteria can be subdivided in at least three major groups.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The recombinant plasmid pRK101 contains a DNA fragment which carries the complete replication origin of the antibiotic resistance factor R1drd-19 inserted into the vector plasmid pBR322. In a spontaneously arising mutant of this plasmid (pRK 103) a deletion of about 215 base pairs (bp) has been detected by heteroduplex analysis and mapping with restriction endonucleases. Essential parts of the replication origin must be located in the deleted sequence. The deletion mutant pRK103, in contrast to its parent plasmid pRK101 is not replicated under the control of the R1 replicon, even when the R1 factor or copy mutants of it are present within the same cell. These latter plasmids can complement a plasmid-specific protein not coded by pRK101 but essential for R1-directed replication. The nucleotide sequence of a 252 bp HpaII fragment covering about 170–200 bp of the deletion was determined. This piece of DNA is rich in G and C and contains a series of small palindromes, symmetrically arranged repeated sequences and short selfcomplementary structures which may be of significance for the initiation of the DNA replication. The possibility that the sequenced DNA fragment comprises a major part of the replication origin of R1drd-19 is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bifunctional recombinant plasmids were constructed, comprised of the E. coli vectors pBR322, pBR325 and pACYC184 and different plasmids from Gram-positive bacteria, e.g. pBSU161-1 of B. subtilis and pUB110 and pC221 of S. aureus. The beta-lactamase (bla) gene and the chloramphenicol acetyltransferase (cat) gene from the E. coli plasmids were not transcribed and therefore not expressed in B. subtilis. However, tetracycline resistance from the E. coli plasmids was expressed in B. subtilis. Transcription of the tetracycline resistance gene(s) started in B. subtilis at or near the original E. coli promoter, the sequence of which is almost identical with the sequence recognized by σ55 of B. subtilis RNA polymerase.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1617-4623
    Keywords: Escherichia coli hemolysin ; Regulation ; hlyR ; Enhancement of hemolysin expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A sequence (hlyR) of about 600 bp which enhances the expression of hemolysin (HlyA) more than 50-fold was identified in the plasmid pHly152-specific hemolysin (hly) determinant. Deletion of this entire hlyR sequence led to the same low level of hemolysin synthesis and excretion as that expressed by the recombinant plasmid pANN202-312. HlyR was active in cis but its activity was orientation-dependent. The enhancing sequence, hlyR, is separated from the promoter phlyI transcribing hlyC, hlyA and possibly hlyB by more than 1.5 kb including an IS2 element. Stepwise removal of the hlyR sequence from its 5′ end by exonuclease III (ExoIII) digestion yielded several types of deletion mutants which expressed decreasing amounts of hemolysin. A similar observation was made when hlyR was shortened by ExoIII from its 3′ end, which suggests that more than one functional region may be present in the hlyR sequence. A deletion of 717 bp within the adjacent IS2 element reduced the activity of hlyR only slightly, indicating that IS2 is not directly involved in the enhancement mechanism but that it may support an optimal positioning in hlyR relative to the hly promoter. The nucleotide sequence of hlyR is rich in A+T and does not contain an extended open reading frame, but exhibits several sequence motives that may represent sites for protein binding and DNA bending.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1617-4623
    Keywords: Secretion ; Recombinant DNA ; Hemolysin ; HlyB/H1yD complementation ; OmpT protease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A fusion gene (ces-hlyA s) was constructed by ligating the genetic information for the C-terminal 60 amino acids (hlyA s) ofEscherichia coli hemolysin (H1yA) to the ces gene for a cholesterol esterase/lipase (CE) from aPseudomonas species. Part (about 30 %) of the expressed fusion protein CE-H1yAs was secreted inE. coli carryinghlyB andhlyD genes. Following the insertion between the reporter gene andhlyA s of a linker sequence that contains the information for potential cleavage sites for the outer membrane protease OmpT, two different fusion proteins (PhoA-H1yAs and CE-HlyAs) were shown to be cleaved by OmpT between the two parts during H1yB/H1yD-mediated secretion. Processed PhoA and CE accumulated in the supernatant. The efficiency of cleavage by OmpT was considerably improved by increasedompT gene dose. It was further shown that OmpT preferentially recognizes potential cleavage sites within the linker sequence.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mini plasmids deriving from pKN102, a copy mutant of the antibiotic resistance factor R1drd-19 of E. coli, share a common DNA sequence of 2.6 kb, which carries the minimal functions for autonomous replication. By cloning of two PstI fragments of this region it could be demonstrated that the “basic replicon” is a DNA segment not larger than 1.8 kb, which carries the origin of replication and the genetic information for at least two proteins. Protein F (MW=11.000 dalton) seems to be synthesed in larger amounts in minicells of E. coli than protein C (20.000 dalton). Plasmids containing this isolated replicon of R1 are completely compatible with the parental plasmid R1drd-19.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In vielen Bakterienzellen treten zusätzlich zur chromosomalen DNA, welche die genetische Information der Zelle enthält, kleinere ringförmige DNA-Faktoren auf, die als Plasmide oder Episomen bezeichnet werden. Diese genetischen Elemente verleihen der Zelle zusätzliche biochemische Fähigkeiten. Beschrieben werden die Fertilitätsfaktoren (F und F′), die Antibiotika-Resistenz-Faktoren (R), die Colicinogenen Faktoren (Col), die Hämolytischen Faktoren (Hly) und andere extrachromosomale DNA-Systeme. Diese kleinen DNA-Moleküle lassen sich isolieren und eignen sich somit besonders, um Fragen der DNA-Replikation und der stabilen Etablierung von genetischem Material in der Bakterienzelle zu untersuchen.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Incubation of the colicinogenic Escherichia coli strain JC 411 (ColE1) at elevated temperatures (47–49°) leads to the accumulation of catenated molecules and replicative intermediates of this plasmid. Mature supercoiled ColE1 DNA molecules synthesized under these conditions have an increased number of tertiary turns as shown by electron microscopy. The monomeric tightly supercoiled molecules possess a slightly slower sedimentation rate and a higher binding capacity for ethidium bromide than supercoiled monomers synthesized at lower temperatures. Recombination deficient mutants of E. coli recA, recB and recC, which carry the ColE1 plasmid, form about the same amount of catenated molecules at the elevated temperature as a rec+ strain. In addition, we have observed by electron microscopy a small percentage (∼5% of the circular DNA molecules) of minicircular DNA molecules in all preparations of JC 411 (ColE1). They are homogenous in size, with a molecular weight of 1.4x106 daltons. Addition of chloramphenicol to a culture of Proteus mirabilis (ColE1) leads to an increased amount of higher multiple circular oligomers and to a stimulated accumulation of catenated ColE1 DNA molecules of varying sizes. ColE1 DNA synthesis is more thermosensitive than chromosomal DNA replication in P. mirabilis. Plasmid replication stops completely at temperatures above 43°C.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The recombinant plasmid pRK101 carrying the complete replication origin of the antibiotic resistance factor R1 suffers frequently a deletion of 218 base pairs, removing parts or all of the origin sequence. This deletion seems to occur always when the Pst-E fragment carrying the replication origin is inserted into the cloning vector pBR322 in an orientation where the direction of R1 replication is the same as that of the vector plasmid and frequently when it is inserted in the opposite direction. DNA sequence analysis around the junction site generated by the deletion in three independently isolated deletion mutants reveals that the deletion occurs at a specific site, namely the end of a 22 bp sequence which is repeated almost identically at the other end of a segment of 197 bp. During the deletion one repeat unit is removed whereas the other is retained. The DNA sequence included by the two repeats contains high symmetric structures, i.e. inverted repeats, direct repeats and palindromes which may represent regulatory sites of the origin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Heterogeneous collections of covalently-closed circular DNA (cccDNA) comprise up to 10% of the total DNA of H. halobium and four other halophilic strains (SB3, GRA, GRB and GN101) recently isolated from different sources. All of these bacteria have purple membrane, bacterioruberin and gas vacuoles as characteristic phenotypic markers. Most of the major cccDNA species of these isolates are not homologous to pHH1, the main 150 kb cccDNA of H. halobium NRC817. Only GN101 and SB3 have a cccDNA which is partly homologous to pHH1. In GN101 the homology is to the halobacterial insertion sequence ISH23 found in pHH1. In SB3 the homology is to ISH26, a new insertion sequence isolated from H. halobium NRC817 which has a size of 1,400 bp. Extensive homologies mologies exist between the minor cccDNA species in all five strains indicating that this cccDNA species is highly conserved and possibly originates from (or is part of) the chromosome. A 1.6 kb high copy number cccDNA species is present in three independently isolated GN101, GRB and SB3. This 1.6 kb cccDNA is not homologous to any other extrachromosomal or chromosomal DNA.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...