Library

X
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
    Electronic Resource
    Electronic Resource
    Promoter identification and expression analysis of Salmonella typhimurium and Escherichia coli nrdEF operons encoding one of two class I ribonucleotide reductases present in both bacteria (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: Salmonella typhimurium and Escherichia coli cells have two different class I ribonucleotide reductases encoded by the nrdEF and nrdAB operons. Despite the presence of one additional ribonucleotide reductase, the nrdAB-encoded enzyme is essential to the aerobic growth of the cell because nrdAB-defective mutants of both species are not viable in the presence of oxygen. Several factors controlling nrdAB gene transcription have been analysed intensively. Nothing is known about the expression of the nrdEF genes. To study this subject, and after cloning of E. coli nrdEF genes and sequencing of their 5′ ends, the promoter of this operon has been identified by primer extension in both bacterial species. The + 1 position was 691 bp and 692 bp upstream of the translational start points of the nrdE genes of S. typhimurium and E. coli, respectively. Downstream of the + 1 position, and before the nrdE gene, two open reading frames (ORFs) of 81 and 136 amino acid residues are present in both bacteria. The synthesis of a polypeptide with a molecular mass of 9 kDa, corresponding to the first of these two ORFs, was observed by using the T7 RNA polymerase expression system. Comparison of the amino acid predicted sequence of this ORF reveals a significant similarity with glutaredoxin proteins. Competitive, reverse-transcription polymerase chain reaction experiments indicate that transcription from the nrdEF promoter normally takes place in wild-type cells. nrdEF transcription is increased by hydroxyurea, which inhibits class I ribonucleotide reductase activity, in both RecA+ and RecA− cells. nrdAts mutants show a higher level of nrdEF transcription than wild-type cells at either the permissive or the restrictive temperature. nrdEF expression was unaffected by changes in DNA supercoiling whether caused by the introduction of either topA ::Tn10 and hns ::Tn10 mutations or by the inhibition of DNA gyrase with the antibiotic novobiocin. In contrast to the nrdAB genes, the nrdEF operon is not essential to the cells because nrdEF-defective mutants are viable under both aerobic and anaerobic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.424950.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Identification of the Rhodobacter sphaeroides SOS box (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: Gel-mobility shift assays with crude cell extracts of Rhodobacter sphaeroides, which belongs to the alpha group of the proteobacteria, have shown that a protein binds to the promoter of its recA gene, resulting in two retardation bands. Analysis of the minimal region of the R. sphaeroides recA gene required for the formation of the DNA–protein complexes, revealed the presence of the motifs GTTCN7GATC and GAACN7GAAC, which are centred at positions −21 and +8 from the transcriptional starting point respectively. Using PCR mutagenesis, we have demonstrated that these two motifs are required for the formation of both DNA–protein complexes in vitro as well as for the DNA damage-mediated inducibility of the recA gene in vivo. Furthermore, the level of the recA gene expression in the constitutive mutants is the same as that achieved by the wild-type cells after DNA damage, indicating that the binding protein must be a repressor. The motif GTTCN7GTTC is also present upstream of the R. sphaeroides uvrA promoter, which in vitro specifically binds to a protein and whose expression is DNA damage inducible. Mutagenesis of this motif abolishes both the binding of this protein to the uvrA promoter and the DNA damage-mediated expression of this gene. The fact that the recA and uvrA wild-type promoters compete with each other for the retardation band formation, but not with their mutant derivatives in any of these motifs, indicates that the same repressor binds to the operator of both genes. All these results lead us to propose the sequence GTTCN7GTTC as the SOS box of R. sphaeroides. This is the first SOS box known whose sequence is a direct repeat and not a palindrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00860.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Widespread distribution of a lexA-regulated DNA damage-inducible multiple gene cassette in the Proteobacteria phylum (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 54 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The SOS response comprises a set of cellular functions aimed at preserving bacterial cell viability in front of DNA injuries. The SOS network, negatively regulated by the LexA protein, is found in many bacterial species that have not suffered major reductions in their gene contents, but presents distinctly divergent LexA-binding sites across the Bacteria domain. In this article, we report the identification and characterization of an imported multiple gene cassette in the Gamma Proteobacterium Pseudomonas putida that encodes a LexA protein, an inhibitor of cell division (SulA), an error-prone polymerase (DinP) and the alpha subunit of DNA polymerase III (DnaE). We also demonstrate that these genes constitute a DNA damage-inducible operon that is regulated by its own encoded LexA protein, and we establish that the latter is a direct derivative of the Gram-positive LexA protein. In addition, in silico analyses reveal that this multiple gene cassette is also present in many Proteobacteria families, and that both its gene content and LexA-binding sequence have evolved over time, ultimately giving rise to the lexA lineage of extant Gamma Proteobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04260.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    LexA-independent DNA damage-mediated induction of gene expression in Myxococcus xanthus (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 49 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Myxococcus xanthus, a member of the Proteobacteria delta-class, has two independent recA genes, recA1 and recA2, but only recA2 is DNA damage-inducible. The lexA gene has been isolated from M. xanthus by PCR amplification with oligonucleotides designed after sequence identification by tblastn analysis of its genome at the Cereon Microbial Sequence Database. The M. xanthus purified LexA protein is shown to bind specifically to the consensus sequence CTRHAMRYBYGTTCAGS present upstream of lexA and recA2. A degenerate copy of this motif but with important differences can be identified in the region upstream of the recA1 gene. A knock-out lexA(Def) mutant that has been generated does not differ significantly from wild type in morphology, growth rate, light-induced carotenogenesis or development. Using transcriptional lacZ fusions and quantitative RT-PCR analysis, it has been demonstrated that expression of both lexA and recA2 genes is constitutive in the lexA(Def) mutant, whereas the transcription of the DNA damage non-inducible recA1 gene is not affected in this strain. recN and ssb, whose expression in Escherichia coli are LexA-regulated, are induced by DNA damage in the M. xanthus lexA(Def) mutant. These data reveal the existence of different regulatory mechanisms for DNA damage-inducible genes in bacteria belonging to different phyla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03592.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of the methoxyneurosporene dehydrogenase gene from Rhodobacter sphaeroides: Comparison with other bacterial carotenoid dehydrogenases (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 93 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The nucleotide sequence of the 1794-bp fragment containing the crtD gene from Rhodobacter sphaeroides 2.4.1 encoding for methoxyneurosporene dehydrogenase has been determined. A 63% sequence identity was found when compared with the nucleotide sequence of the crtD gene from Rhodobacter capsulatus. A putative regulatory palindromic motif present in the crtD gene from R. capsulatus also exists in this gene from R. sphaeroides. The translated open reading frame of the crtD gene of R. sphaeroides has identified a polypeptide of 495 amino acids which shares a 56% sequence identity with the same CrtD protein of R. capsulatus. The N- and C- termini of these CrtD proteins present a high degree of similarity with the N- and C-termini of other carotenoid dehydrogenases including those encoded by crtI genes. This is in good agreement with the previously hypothesized homology between CrtI and CrtD proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05048.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Expression of nrdA and nrdB genes of Escherichia coli is decreased under anaerobiosis (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 83 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: By using plasmid nrdA-lacZ, nrdAB-lacZ, and nrdB-lacZ gene fusions, the expression of nrdA and nrdB genes of Escherichia coli under anaerobiosis has been studied. The results obtained show that cells of E. coli growing under either fermentative or nitrate respiring conditions present a lower basal level of both nrdA and nrdB genes transcription from the nrdPA promoter. On the other hand, transcription of the nrdB gene from the internal nrdPB promoter was not affected by the absence of oxygen. Moreover, the DNA damage-mediated inducing factor of these nrd genes was the same in both aerobic and anaerobic cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04432.x-i1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Expression of the Pasteurella multocida ompH gene is negatively regulated by the Fur protein (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 203 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The fur gene of Pasteurella multocida has been cloned by complementation of an Escherichia coli fur mutant. The P. multocida fur gene, which encodes a predicted protein of 147 amino acids, displaying the highest identity (89%) with the same protein of Haemophilus influenzae, is negatively regulated by its own product. By construction of a P. multocida fur mutant, it has been demonstrated that the ompH gene, encoding a major structural protein of the outer membrane, presenting high antigenicity power, is negatively regulated by iron and glucose. Furthermore, wild-type and fur-defective cells of P. multocida show the same level of virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10817.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The high-affinity zinc-uptake system znuACB is under control of the iron-uptake regulator (fur) gene in the animal pathogen Pasteurella multocida (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 221 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The Pasteurella multocida znuACB genes encoding a high-affinity zinc-uptake system have been identified and cloned. In contrast to what happens in Escherichia coli, znuA is not physically linked to znuCB. Through lacZ transcriptional fusions it has been demonstrated that zinc negatively regulates both znuA and znuCB operons. Nevertheless, and contrary to that determined so far for all other znuACB bacterial systems known, P. multocida znuACB genes are not under control of the zur gene, which is absent in this bacterial species, but rather are under its iron-uptake regulator (fur) gene. Furthermore, construction of defective mutants has demonstrated that P. multocida znuA and znuCB transcriptional units are required for virulence of this organism in a mouse model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00131-9
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Virulence and mutation rates of Salmonella typhimurium strains with increased mutagenic strength in a mouse model (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 187 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Two strains of Salmonella typhimurium presenting increased mutation rates, either spontaneous or mediated by DNA damage, have been constructed. One of the strains carries a null mutS mutation, while the other harbors plasmid pRW30, which contains the Escherichia coli umuDC operon. The virulence of these strains has been determined by inoculating BALB/c or Swiss mice. The 50% lethal dose of both strains is identical to that obtained for the wild-type. Likewise, the two strains and the wild-type contribute equally to animal death in mixed infections. The frequency of NalR mutants recovered from animals inoculated with either wild-type or MutS− cells was not affected by the presence of pRW30. These results indicate that the DNA damage which S. typhimurium cells can suffer during the infectious process by host cell metabolites does not cause induction of the SOS response at levels able to trigger the error-prone DNA repair pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09151.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A consensus sequence for the Rhodospirillaceae SOS operators (1999)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 171 (1999), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The sequences controlling the expression of the Rhodobacter capsulatus recA and uvrA genes belonging to the SOS DNA repair system have been identified by PCR mutagenesis. Data obtained demonstrated that the GTTCN7GTAC and GAACN7GAAC motifs present upstream of the recA gene and the GTTCN7GTTC motif found upstream of the uvrA gene are required for their respective DNA damage-mediated induction. Alignment of recA promoters of R. capsulatus, Rhodobacter sphaeroides and Rhodopseudomonas viridis with the uvrA promoters of R. capsulatus and R. sphaeroides has identified the consensus sequence GTTCVYVYTWTGTTC as the SOS operator site of the Rhodospirillaceae family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1999.tb13409.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...