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  • 1995-1999  (10)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Destabilized inheritance of pSC101 and other Escherichia coli plasmids by DpiA, a novel two-component system regulator (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 29 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We identified a gene (dpiAdestabilizer of plasmid inheritance) which, when overexpressed in Escherichia coli, destabilizes the inheritance of pSC101 and other iteron-containing plasmids as disparate as mini-F and RK6 but not the inheritance of P1, RSF1010 and ColD. These effects of DpiA, which functions like an effector protein for a previously undescribed two-component signal transduction system, were reduced by mutations known to promote pSC101 replication and partitioning. dpiB, a gene encoding the putative histidine kinase of this two-component system, is located immediately 5′ to dpiA and adjacent to a DpiA-induced target promoter that transcribes genes having homology to citrate lyase operon genes, citC, citD and citE, of Klebsiella pneumoniae. Disruption of dpiB reversed or reduced the effect of DpiA overproduction on pSC101 inheritance. A second DpiA target, the promoter for a gene (appY ) implicated in E. coli's response to anaerobiosis, is repressed by DpiA. A mutation in dpiA at a site commonly conserved and phosphorylated in two-component system effector proteins abolished the effects of DpiA overproduction on pSC101 inheritance and negative regulation of appY expression. Our findings suggest a possible mechanism by which environmental and/or cellular stimuli may influence plasmid inheritance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00895.x
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  • 2
    Electronic Resource
    Electronic Resource
    A developmentally regulated Streptomyces endoribonuclease resembles ribonuclease E of Escherichia coli (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 25 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We report that the Streptomyces species S. lividans and S. coelicolor, morphologically complex Gram-positive soil bacteria, contain a developmentally regulated endoribonuclease activity (here named RNase ES) that functionally and immunologically resembles Escherichia coli RNase E. In Streptomyces cells, RNA I — the antisense repressor of replication of ColE1-type plasmids — is cleaved at sites attacked by RNase E. A Mg2+-dependent endonuclease that produces RNase E-like cleavages in RNA I and 9S ribosomal RNA was identified in S. lividans cell extracts. A Streptomyces peptide migrating at 70 kDa in SDS/polyacrylamide gels binds to RNase E substrates and reacts with three separate anti-RNase E monoclonal antibodies; the endonucleolytic cleavage activity co-purified with the immunoreactive 70 kDa peptide. We show that RNase ES activity is regulated during the Streptomyces life cycle: activity increased as cells progressed from exponential growth to stationary phase in liquid culture, or from mycelial growth to sporulation on solid media. While mutations that interfere with S. coelicolor development late in its life cycle did not prevent this developmentally associated increase in RNase ES activity, the increase was blocked by a mutation (bldA) that interferes early with both morphological and physiological differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.5311904.x
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  • 3
    Electronic Resource
    Electronic Resource
    Replication at the telomeres of the Streptomyces linear plasmid pSLA2 (1998)
    Oxford BSL : Blackwell Publishing Ltd
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Streptomyces linear plasmid pSLA2 initiates DNA replication bidirectionally towards its telomeres from a site located near the centre of the molecule; at the telomeres, the recessed ends of lagging strands are filled in by non-displacing DNA synthesis. Here, we report experiments that test three proposed mechanisms for lagging-strand fill-in. We present data inconsistent with recombinational or terminal hairpin models for the formation of full-length duplex pSLA2 DNA. Instead, we find that deletions in short, distantly separated homologous palindromes in the leading-strand 3′ overhang prevent propagation of linear pSLA2 DNA, implicating a mechanism of palindrome-mediated leading-strand fold-back in telomere replication. We further show that circularized pSLA2 DNA molecules are opened in vivo precisely at the terminal nucleotides of telomeres, generating functional linear replicons containing native telomeres covalently bound to a protein at their 5′ DNA termini. Together, our results support a model in which pairing of multiple widely separated pSLA2 palindromes anchors the 3′ end of the leading-strand overhang to a site near the overhang's base — providing a recognition site for terminal-protein-primed DNA synthesis and subsequent endonucleolytic processing. Thus, the replication of Streptomyces plasmid telomeres may have features in common with the mechanism proposed for telomere replication in autonomous parvoviruses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00838.x
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  • 4
    Electronic Resource
    Electronic Resource
    RNase E: still a wonderfully mysterious enzyme (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ribonuclease E (RNase E), which is encoded by an essential Escherichia coli gene known variously as rne, ams, and hmp, was discovered initially as an rRNA-processing enzyme but is now known to have a general role in RNA decay. Multiple functions, including the ability to cleave RNA endonucleolyticaliy in AU-rich single-strand regions, RNA-binding capabilities, and the ability to interact with polynucleotide phosphorylase and other proteins implicated in the processing and degradation of RNA, are encoded by its 1061 amino acid residues. The presence of homologues and functional analogues of the rne gene in a variety of prokaryotic and eukaryotic species suggests that its functions have been highly conserved during evolution. While much has been learned in recent years about the structure and functions of RNase E, there is continuing mystery about possible additional activities and molecular interactions of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1997.tb02593.x
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(A)- and poly(U)-specific RNA 3′ tail shortening by E. coli ribonuclease E (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 391 (1998), S. 99-102 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Ribonuclease (RNase) E is an extensively studied enzyme from Escherichia coli whose site-specific endoribonuclease activity on single-stranded RNA has a central role in the processing of ribosomal RNA, the degradation of messenger RNA and the control of replication of ColE1-type plasmids (for ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/34219
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Streptomyces linear plasmids that contain a phage-like, centrally located, replication origin (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 22 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Unlike previously studied linear replicons containing 5′ DNA termini covalently bound to protein, pSLA2, a 17 kb linear plasmid of Streptomyces rochei, initiates replication internally rather than at the telomeres (Chang and Cohen, 1994). Here we identify and characterize the replication origin of pSLA2, showing that it contains a series of direct repeats (iterons) within a centrally located gene encoding an essential DNA-binding protein (Rep1); a second essential protein (Rep2), which resembles prokaryotic DNA helicases and has ATPase activity stimulated by single-stranded DNA, is expressed from the same transcript. A 430 bp locus separated by almost 2 kb from the iterons of the origin specifies an as yet undefined additional function required in cis for plasmid replication. pSCL, a 12 kb linear plasmid of Streptomyces clavuligerus, contains, near the centre of the plasmid, a region configured like the pSLA2 origin. The replication regions of pSLA2 and pSCL, which are capable of propagating plasmid DNA in either a circular or linear form (Shiffman and Cohen, 1992; Chang and Cohen, 1994) resemble those of temperate bacteriophages of the Enterobacteriacae and Bacillus. Our observations suggest that Streptomyces linear plasmids may occupy an evolutionarily intermediate position between circular plasmids and linear phage replicons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.01526.x
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  • 7
    Electronic Resource
    Electronic Resource
    Plasmid transfer and expression of the transfer (tra) gene product of plasmid pIJ101 are temporally regulated during the Streptomyces lividans life cycle (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 19 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We previously have shown that a chromosomally integrated copy of the tra gene of plasmid pIJ101 under the control of the KorA repressor protein, which regulates transcription of tra as well as its own synthesis, can promote the conjugal transfer of both chromosomal and plasmid genes in Streptomyces lividans. Using an antibody generated against a fusion protein containing the C-terminal portion of Tra, we show here that this essential conjugation protein is present in membrane fractions of both surface-grown S. lividans, which mate readily, and of cells grown in liquid culture, where mating has not been found. Expression of Tra during the S. lividans life cycle was temporally regulated and was reduced late during vegetative growth so that little or no Tra protein was detected in cells as they began to differentiate morphologically and produce secondary metabolites. Comparison of the membrane concentration of Tra protein with tra mRNA concentration during the S. lividans life cycle indicated that the disappearance of Tra is post-transcriptionally controlled and thus is not mediated by KorA. The results of ‘interrupted mating’ experiments, together with the time of appearance of Tra in S. lividans membranes, indicate that the intermycelial transfer of pIJ101 in S. lividans is complete by the onset of cellular differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.493986.x
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  • 8
    Electronic Resource
    Electronic Resource
    Transfer of the pIJ101 plasmid in Streptomyces lividans requires a cis-acting function dispensable for chromosomal gene transfer (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 16 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.tb02402.x
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  • 9
    Electronic Resource
    Electronic Resource
    Site-specific RNase E cleavage of oligonucleotides and inhibition by stem–loops (1995)
    [s.l.] : Nature Publishing Group
    Nature 374 (1995), S. 287-290 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] RNase E cleaves RNAs of known secondary structure (such as RNA I, 9S ribosomal RNA, S20 messenger RNA) within single-stranded regions rich in A + U nucleotides6'8'11 (see Fig. la for pBR322 RNA I). Mutational modification of the single-stranded segment bracketing the RNase E cleavage site at the 5' ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/374287a0
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  • 10
    Electronic Resource
    Electronic Resource
    RNA degradation in Escherichia coli regulated by 3' adenylation and 5' phosphorylation (1995)
    [s.l.] : Nature Publishing Group
    Nature 374 (1995), S. 180-183 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Endonucleolytic cleavage of RNA I (Fig. 1) near its 5' end by ribonuclease E (RNase E) in E. coli cells generates products that ordinarily are rapidly degraded11. Although these products have the same 5' monophosphate terminus, there is heterogeneity at the 3' end8. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/374180a0
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