Overproduction of exopolysaccharides by an Escherichia coli K-12 rpoS mutant in response to osmotic stress.

ABSTRACT: The yjbEFGH operon is implicated in the production of an exopolysaccharide of an unknown function and is induced by osmotic stress and negatively regulated by the general stress response sigma factor RpoS. Despite the obvious importance of RpoS, negative selection for rpoS has been reported to take place in starved cultures, suggesting an adaptive occurrence allowing the overexpression of RpoD-dependent uptake and nutrient-scavenging systems. The trade-off of the RpoS-dependent functions for improved nutrient utilization abilities makes the bacterium more sensitive to environmental stressors, e.g., osmotic stress. In this work, we addressed the hypothesis that overinduction of genes in rpoS-deficient strains indicates their essentiality. Using DNA microarrays, real-time PCR, and transcript

SUBMITTER: Ionescu M 

PROVIDER: S-EPMC2620720 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature