RpoS May Not Play a Central Role in Coordinating Heat Shock Stress Response and Antibiotic Tolerance

Abstract

The stationary phase sigma factor, RpoS, is a mediator of the general stress response in Escherichia coli exposed to environmental stress. The general stress response confers protection to other stresses including increased tolerance to tetracycline. Although RpoS is generally up-regulated under stress conditions, the regulatory RNA oxy S, upregulated in the presence of oxidative stress, negatively regulates rpo S expression. This study addressed the regulatory relationship between RpoS and oxy S, and the resulting impact on tetracycline resistance. A culture subjected to heat shock stress was subsequently exposed to oxidative stress using a wild type E. coli and an isogenic derivative bearing a deletion of rpo S. Contrary to expectations, RpoS expression decreased following heat shock treatment and increase in tetracycline tolerance was not observed. PCR amplification of the oxy S RNA converted to cDNA showed a subtle increase in oxy S expression following oxidative stress. The impact of oxidative stress and the oxy S RNA on RpoS expression remains unclear. Thus, our data suggests that RpoS may not play a central role in coordinating the heat shock stress response and tolerance to tetracycline.