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  • 1
    Electronic Resource
    Electronic Resource
    Regulation of competence for genetic transformation in Streptococcus pneumoniae: expression of dpnA, a late competence gene encoding a DNA methyltransferase of the DpnII restriction system (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 35 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The chromosomal DpnII gene cassette of Streptococcus pneumoniae encodes two methyltransferases and an endonuclease. One methyltransferase acts on double-stranded and the other on single-stranded DNA. Two mRNAs are transcribed from the cassette. One, a SigA promoter transcript, includes all three genes; the other includes a truncated form of the second methyltransferase gene (dpnA) and the endonuclease gene. The truncated dpnA, which is translated from the second start codon in the full gene, was shown to produce active enzyme. A promoter reporter plasmid for S. pneumoniae was devised to characterize the promoter for the second mRNA. This transcript was found to depend on a promoter that responded to the induction of competence for genetic transformation. The promoter contains the combox sequence recognized by a SigH-containing RNA polymerase. As part of the competence regulon, the dpnA gene makes a product able to methylate incoming plasmid strands to protect them from the endonuclease and allow plasmid establishment. Its function differs from most genes in the regulon, which are involved in DNA uptake. Comparison of R6 and Rx strains of S. pneumoniae showed the temperature dependence of transformation in R6 to result from temperature sensitivity of the uptake apparatus and not the development of competence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.01777.x
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  • 2
    Electronic Resource
    Electronic Resource
    Constitutive competence for genetic transformation in Streptococcus pneumoniae caused by mutation of a transmembrane histidine kinase (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 42 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Competence for DNA uptake and genetic transformation in Streptococcus pneumoniae is regulated by a quorum-sensing system. A competence-stimulating polypeptide (CSP) is secreted by the bacteria and acts back on the cells via a transmembrane histidine kinase. This enzyme phosphorylates a response regulator that activates synthesis of a SigH-like protein. The new sigma factor enables expression of a set of proteins transcribed from a novel promoter. A mutation called trt had been found that circumvented this regulation. The mutant cells are constitutively competent; that is, they can be transformed at low cell densities, in the presence of proteases that attack CSP, or during growth at low pH. In this work, cells containing trt were shown to be competent even in the presence of a comAB mutation that blocks secretion of CSP. The trt mutation was localized to comD, the gene encoding the transmembrane histidine kinase. A DNA segment of the trt mutant corresponding to comCDE was cloned, and it was shown to contain the trt mutation by its ability to confer constitutive competence. A two-step assay, which was based on transfer of trt to a wild strain and screening for transformability in the presence of trypsin, served to locate the trt mutation precisely. It corresponds to a GC→AT transition, which changes Asp299 in the histidine kinase to Asn. This alteration in the carboxyl terminal half of the protein, which is cytoplasmically located and contains the phosphorylase activity, presumably alters the enzyme conformation so that it is permanently activated, independent of signals from the transmembrane domain. These results may help illuminate the mechanism by which external signals affect kinase action in two-component regulatory systems, and they may be of practical value in facilitating genetic studies by rendering pneumococcal strains permanently competent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02697.x
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  • 3
    Electronic Resource
    Electronic Resource
    Multiple roles for DNA polymerase I in establishment and replication of the promiscuous plasmid pLS1 (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 14 (1994), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The polymerase activity of DNA polymerase I is important for the establishment of the pLS1 replicon by reconstitutive assembly in Streptococcus pneumoniae after uptake of exogenous pLS1 plasmid DNA. In polA mutants lacking the polymerase domain, such establishment was reduced at least 10-fold in frequency. Chromosomally facilitated establishment of pLS1-based plasmids carrying DNA homologous to the host chromosome was not so affected. However, both types of plasmid transfer gave mostly small colonies on initial selection, which was indicative of a defect in replication and filling of the plasmid pool. Once established, the pLS1-based plasmids replicated in polA mutants, but they showed segregational instability. This defect was not observed in strains with the wild-type enzyme or in an S. pneumoniae strain that encodes the polymerase and exonuclease domains of the enzyme on separate fragments. The role of DNA polymerase I in stably maintaining the plasmids depends on its polymerizing function in three separate steps of rolling-circle replication, as indicated by the accumulation of different replication intermediate forms in polA mutants. Furthermore, examination of the segregational stability of the pLS1 replicon in an Escherichia coli mutant system indicated that both the polymerase and the 5′-to-3′ exonuclease activities of DNA polymerase I function in plasmid replication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1994.tb01314.x
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  • 4
    Electronic Resource
    Electronic Resource
    The 5′ to 3′ exonuclease activity of DNA polymerase I is essential for Streptococcus pneumoniae (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 6 (1992), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Three different mutations were introduced in the polA gene of Streptococcus pneumoniae by chromosomal transformation. One mutant gene encodes a truncated protein that possesses 5′ to 3′ exonuclease but has lost polymerase activity. This mutation does not affect cell viability. Other mutated forms of polA that encode proteins with only polymerase activity or with no enzymatic activity could not substitute for the wild-type polA gene in the chromosome unless the 5′ to 3′ exonuclease domain was encoded elsewhere in the chromosome. Thus, it appears that the 5′ to 3′ exonuclease activity of the DNA polymerase I is essential for cell viability in S. pneumoniae. Absence of the polymerase domain of DNA polymerase I slightly diminished the ability of S. pneumoniae to repair DNA lesions after ultraviolet irradiation. However, the polymerase domain of the pneumococcal DNA polymerase I gave almost complete complementation of the polA5 mutation in Escherichia coli with respect to resistance to ultraviolet irradiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1992.tb01759.x
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  • 5
    Electronic Resource
    Electronic Resource
    Physical structure and genetic expression of the sulfonamide-resistance plasmid pLS80 and its derivatives in Streptococcus pneumoniae and Bacillus subtilis (1984)
    Springer
    Molecular genetics and genomics 195 (1984), S. 402-410 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The 10-kb chromosomal fragment of Streptococus pneumoniae cloned in pLS80 contains the sul-d allele of the pneumococcal gene for dihydropteroate synthase. As a single copy in the chromosome this allele confers resistance to sulfanilamide at 0.2 mg/ml; in the multicopy plasmid it confers resistance to 2.0 mg/ml. The sul-d mutation was mapped by restriction analysis to a 0.4-kb region. By the mechanism of chromosomal facilitation, in which the chromosome restores information to an entering plasmid fragment, a BamHI fragment missing the sul-d region of pLS80 established the full-sized plasmid, but with the sul-s allele of the recipient chromosome. A spontaneous deletion beginning ∼1.5 kb to the right of the sul-d mutation prevented gene function, possibly by removing a promoter. This region could be restored by chromosomal facilitation and be demonstrated in the plasmid by selection for sulfonamide resistance. Under selection for a vector marker, tetracycline resistance, only the deleted plasmid was detectable, apparently as a result of plasmid segregation and the advantageous growth rates of cells with smaller plasmids. When such cells were selected for sulfonamide resistance, the deleted region returned to the plasmid, presumably by equilibration between the chromosome and the plasmid pool, to give a low frequency (∼10-3) of cells resistant to sulfanilamide at 2.0 mg/ml. Models for the mechanisms of chromosomal facilitation and equilibration are proposed. Several derivatives of pLS80 could be transferred to Bacillus subtilis, where they conferred resistance to sulfanil-amide at 2 mg/ml, thereby demonstrating cross-species expression of the pneumococcal gene. Transfer of the plasmids to B. subtilis gave rise to large deletions to the left of the sul-d marker, but these deletions did not interfere with the sul-d gene function. Restriction maps of pLS80 and its variously deleted derivatives are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341440
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  • 6
    Electronic Resource
    Electronic Resource
    Interspecific plasmid transfer between Streptococcus pneumoniae and Bacillus subtilis (1982)
    Springer
    Molecular genetics and genomics 188 (1982), S. 195-201 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The streptococcal plasmids pMV158 and pLS1, grown in Streptococcus pneumoniae, were transferred to Bacillus subtilis by DNA-mediated transformation. The plasmids were unchanged in the new host; no deletions were observed in 80 instances of transfer. Their copy number was similar to that in S. pneumoniae. Two B. subtilis plasmids, pUB110 and pBD6, could not be transferred to S. pneumoniae. Hybrid plasmids were produced by recombining the EcoRI fragment of pBD6 that confers Kmr with EcoRI-cut pLS1, which confers Tcr. The simple hybrid, pMP2, was transferable to both species and expressed Tcr and Kmr in both. A derivative, pMP5, which contained an insertion in the pBD6 component, expressed a higher level of kanomycin resistance and was more easily selected in S. pneumoniae. Another derivative, pMP3, which contained an additional EcoRI fragment, presumably of pneumococcal chromosomal DNA, could not be transferred to B. subtilis. Previous findings that monomeric plasmid forms could transform S. pneumoniae but not B. subtilis were confirmed using single plasmid preparations. Although plasmids extracted from either species were readily transferred to S. pneumoniae, successive passage in B. subtilis increased the ability of plasmid extracts to transfer the plasmid to a B. subtilis recipient. This adaptation was tentatively ascribed to an enrichment of multimeric forms in extracts of B. subtilis as compared to S. pneumoniae. A review of host ranges exhibited by plasmids of Gram-positive bacteria suggested differences in their ability to use particular host replication functions. The pMP5 plasmid, with readily selectable Kmr and Tcr markers in both hosts, and with the potential for inactivation of Kmr by insertion in the Bg/II site, could be a useful shuttle vector for cloning in S. pneumoniae and B. subtilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332675
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  • 7
    Electronic Resource
    Electronic Resource
    Nonsense mutations in the amylomaltase gene and other loci of Streptococcus pneumoniae (1981)
    Springer
    Molecular genetics and genomics 183 (1981), S. 7-12 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maltose-negative mutations in the amylomaltase gene of Streptococcus pneumoniae were examined for the presence of nonsense mutations. Out of 28 single-site mutants tested, 3 were shown to be suppressible by an amber suppressor previously found by Gasc et al. (1979). In the presence of the suppressor these mutants manifested 10–30% of wild type amylomaltase activity. In addition to the amylomaltase governed by malM, and the maltosaccharide phosphorylase governed by malP (which maps to the side of malM distal to the regulatory gene, malR), a new maltose-inducible protein, governed by another gene, malX, was observed in gel electrophoretic patterns. The malX gene maps on the side of malM proximal to the malR gene. The approximate molecular weights of the amylomaltase, phosphorylase and malX polypeptides are 62,000, 87,000 and 50,000, respectively. There appear to be no polar effects of the nonsense mutations in the malM gene on synthesis of the gene products of either malP or malX. In a search for nonsense mutants at other loci, one was found in the end gene, which governs the major endonuclease, a membrane enzyme. None were detected among 5 mismatch-repair defective hex mutants analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270130
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  • 8
    Electronic Resource
    Electronic Resource
    Complementation of Bacillus subtilis polA mutants by DNA polymerase I from Streptococcus pneumoniae (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 203-210 
    Details
    ISSN: 1617-4623
    Keywords: DNA repair ; UV resistance ; Ectopic integration ; Gene dosage ; Heterospecific gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The polA gene of Streptococcus pneumoniae cloned in the recombinant plasmid pSM22 is expressed in Bacillus subtilis. Extracts of B. subtilis polA mutants containing pSM22 showed 6 times more DNA polymerase activity than extracts of wild-type cells without the plasmid. Complete complementation of the B. subtilis polA5 and polA59 mutations with respect to in vivo resistance to UV irradiation and methyl methanesulfonate was observed when four copies of the pneumococcal polA gene were present in each cell. Ectopic integration of the polA gene together with a cat marker into the chromosome of B. subtilis gave chromosomal insertions containing single and double doses of the pneumococcal polA gene. Correlation with gene dosage was observed for both chloramphenicol acetyltransferase and DNA polymerase activities measured in vitro. Depending on the number of copies of the S. pneumoniae polA gene present, restoration of DNA repair functions in polA mutants of B. subtilis was either partial or complete.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325685
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  • 9
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    Crystal structure of the DpnM DNA adenine methyltransferase from the DpnII restriction system of Streptococcus pneumoniae bound to S-adenosylmethionine (1998)
    Cell Press
    Details
    Publication Date: 1998-12-01
    Print ISSN: 0969-2126
    Electronic ISSN: 1878-4186
    Topics: Biology , Medicine
    Published by Cell Press
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  • 10
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    DNA methylation and cellular differentiation. Cell biology monographs, vol. 11 (1985)
    Cell Press
    Details
    Publication Date: 1985-02-01
    Print ISSN: 0968-0004
    Electronic ISSN: 1362-4326
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Cell Press
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