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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 68 (1990), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The Escherichia coli serB gene is divergently transcribed from the gene. Six indenpendently isolated IS30 insertions within the 5′ end of the serB strucutral gene resulted in increased expression of an smp'-lacZ gene fusion. DNA sequence analysis of two of the insertions suggests that a promoter was created upon IS30 insertion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 144 (1996), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Inactivation of either of the two MetR binding sites centered at bp —143 and —121 relative to the +1 transcription start site results in reduced glyA-lacZ expression in a wild-type strain below the level seen in a metR mutant. This reduced expression is dependent on the side of the DNA helix MetR binds relative to the RNA polymerase binding site. Thus, a single MetR dimer bound to the DNA may play a physiological role in maintaining appropriate glyA gene expression, functioning as a represser under low MetR conditions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 108 (1993), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract In Salmonella typhimurium the metE and metR promoters overlap and are divergently transcribed. Three tandem repeats of an 8 bp sequence defined previously as the metE operator site for MetJ-mediated repression also overlap the −35 region of the metR promoter. Starting with a metE-lacZ · metR-galK double gene fusion, site-directed mutagenesis was used to change nucleotides in each of the repeat units from the consensus sequence. Each mutation, along with the wild-type metE-lacZ · metR-galK gene fusion, was cloned into phage λgt2. Regulation of the metE and metR genes was examined by measuring β-galactosidase and galactokinase levels in Escherichia coli strains lysogenized with phage carrying the wild-type and mutant fusions. Mutations in each of the 8 bp repeat units disrupt MetJ-mediated repression for both the metE-lacZ and metR-galK gene fusions, suggesting that the metE and metR genes share a common operator site for the MetJ repressor.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 242 (2005), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The glycine cleavage enzyme system in Escherichia coli provides one-carbon units for cellular methylation reactions. The gcvB gene encodes two small RNAs that in turn regulate other genes. The GcvA protein is required for expression of both the gcvTHP (PgcvT) and gcvB (PgcvB) promoters. However, the architectures of the two promoters are different, with the PgcvT promoter representing a class III activator-dependent promoter and the PgcvB promoter representing a class II activator-dependent promoter. The RNA polymerase holoenzyme was examined for its role in transcription activation of the gcvTHP operon and the gcvB gene by the GcvA protein. The results suggest that GcvA interacts with the RNA polymerase α subunit for activation of the gcvTHP operon and interacts with the RNA polymerase σ subunit for activation of the gcvB gene.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Escherichia coli gcvB gene encodes a small RNA transcript that is not translated in vivo. Transcription from the gcvB promoter is activated by the GcvA protein and repressed by the GcvR protein, the transcriptional regulators of the gcvTHP operon encoding the enzymes of the glycine cleavage system. A strain carrying a chromosomal deletion of gcvB exhibits normal regulation of gcvTHP expression and glycine cleavage enzyme activity. However, this mutant has high constitutive synthesis of OppA and DppA, the periplasmic-binding protein components of the two major peptide transport systems normally repressed in cells growing in rich medium. The altered regulation of oppA and dppA was also demonstrated using oppA–phoA and dppA–lacZ gene fusions. Although the mechanism(s) involving gcvB in the repression of these two genes is not known, oppA regulation appears to be at the translational level, whereas dppA regulation occurs at the mRNA level.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 181 (1999), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Several LysR-type transcriptional regulators have been shown to require the carboxy-terminal domain of the α subunit (αCTD) of RNA polymerase to activate their target genes. We show here that GcvA, a LysR-type protein, also uses the αCTD to activate the Escherichia coli gcvTHP operon. Amino acid residues in the αCTD important for GcvA-dependent activation, however, have no effect on GcvA-mediated repression of the operon.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 60 (1989), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract We used an Escherichia coli lac deletion strain lysogenized with a metC-lacZ fusion phage (λClac) to select operator-constitutive mutations in the Salmonella typhimurium metC gene control region. The mutations were located in a region containing 2 tandemly repeated 8 bp palindromes previously proposed to be the MetJ repressor binding site. Lysogens carrying λClac mutant phage exhibit high β-galactosidase levels that are only partially repressible by methionine. The results suggest that the mutations disrupt the methionine control system mediated by the metJ gene product.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 137 (1996), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract We determined the relative binding affinity of the MetR protein for wild-type and mutant MetR binding sites 1 and 2 in the Escherichia coli glyA control region. The results show that MetR binding site 1 has a higher affinity for the MetR protein than binding site 2. In addition, the results suggest that binding of MetR to the glyA promoter is cooperative. Mutations that decrease the ability of MetR to bind to either site 1 or site 2 have no significant effect on MetR's ability to bend DNA.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 99 (1992), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Site-directed mutagenesis was used to change the PurR binding site in the control region of a glyA-lac gene fusion. Mutations that changed the PurR binding sequence away from the consensus sequence reduced PurR binding, which correlated with reduced purine-mediated repression. Mutations that changed the binding sequence toward the consensus sequence had no significant effect on either PurR binding or purine-mediated repression. Hypoxanthine and guanine, co-repressors for PurR-mediated regulation of the pur regulon, increased binding of PurR to glyA operator DNA.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1617-4623
    Keywords: metF ; 5,10-methylenetetrahydrofolate reductase ; Recombinant DNA ; Nucleotide sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Salmonella typhimurium LT2 metF gene, encoding 5,10-methylenetetrahydrofolate reductase, has been cloned. Strains with multicopy plasmids carrying the metF gene overproduce the enzyme 44-fold. The nucleotide sequence of the metF gene was determined, and an open reading frame of 888 nucleotides was identified. The polypeptide deduced from the DNA sequence contains 296 amino acids and has a molecular weight of 33 135 daltons. Mung bean nuclease mapping experiments located the transcription start point and possible transcription termination region for the gene. There is a 25bp nucleotide sequence between the translation termination site and the possible transcription termination region. This region possesses a GC-rich sequence that could form a stable stem and loop structure once transcribed (ΔG=-9 kcal/mol), followed by an AT-rich sequence, both of which are characteristic of rho-independent transcription terminators. The nucleotide and deduced amino acid sequences of the S. typhimurium metF gene are compared with the corresponding sequences of the Escherichia coli metF gene. The nucleotide sequences show 85% homology. Most of the nucleotide differences found do not alter the amino acid sequences, which show 95% homology. The results also show that a change has occurred in the metF region of the S. typhimurium chromosome as compared to the E. coli chromosome.
    Type of Medium: Electronic Resource
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