High frequency of hotspot mutations in core genes of Escherichia coli due to short-term positive selection.

ABSTRACT: Core genes comprising the ubiquitous backbone of bacterial genomes are not subject to frequent horizontal transfer and generally are not thought to contribute to the adaptive evolution of bacterial pathogens. We determined, however, that at least one-third and possibly more than one-half of the core genes in Escherichia coli genomes are targeted by repeated replacement substitutions in the same amino acid positions-hotspot mutations. Occurrence of hotspot mutations is driven by positive selection, as their rate is significantly higher than expected by random chance alone, and neither intragenic recombination nor increased mutability can explain the observed patterns. Also, commensal E. coli strains have a significantly lower frequency of mutated genes and mutations per genome than pathogen

SUBMITTER: Chattopadhyay S 

PROVIDER: S-EPMC2718352 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature