A new phenotype for sbcB mutations in Escherichia coli: RecA-dependent increase in plasmid-borne gene expression.
A new chromosomal mutation (cpeA), that causes increased expression of plasmid-borne genes in Escherichia coli, was identified and mapped to the sbcB locus. The effect of the mutation on plasmid transcription was non-specific with respect to the various promoters that were studied, but was more pronounced for an IncW low-copy-number plasmid than for ColE1- or p15A-based, high-copy-number plasmids. The mutant phenotype was observed even in recB+C+D+ strains, but not in recA mutants. The increased-expression phenotype was also observed in sbcB15 but not in xonA1 (another sbcB allele) mutants, suggesting that the expression of this phenotype is mediated by genes of the so-called RecF pathway family. Consistent with this interpretation was the observation that the cpeA mutant phenotype was less pronounced in recF, recJ and recO mutants. The increased-expression phenotype was also correlated with increased recovery of plasmid DNA from the cpeA/sbcB mutant strains, but there was no evidence for the occurrence of linear plasmid multimers in these strains.
Jayashree
P
P
Centre for Cellular and Molecular Biology, Hyderabad, India.
Gowrishankar
J
J
D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D009154:Mutation; D009690:Nucleic Acid Conformation; D009995:Osmosis; D010641:Phenotype; D010957:Plasmids / Q000737:chemistry / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics*
D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C060774:ProU protein, Bacteria; C489340:recF protein, E coli; C066218:recF protein, Bacteria; D011938:Rec A Recombinases