A new phenotype for shcB mutations in Escherichia coli: RecA-dependent increase in plasmid-borne gene expression

Abstract

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.

Analysis of Hematological Traits in Polled Yak by Genome-Wide Association Studies Using Individual SNPs and Haplotypes

“…Individual haplotype blocks and haplotype frequency were detected using the standard expectation maximization (EM) [37] algorithm. Reference thresholds and partitioning criteria for SNPs within closely linked haplotypes were established following the recommendations of the user manual of the PLINK software [32].…”