Effect of σS on σE-Directed Cell Lysis in Escherichia coli Early Stationary Phase

Abstract
The sigmaE regulon has been shown to perform a novel function that causes dead-cell lysis specific to the early stationary phase in addition to its well-known role in the extracytoplasmic stress response in Escherichia coli. Here, the effect of sigmaS as a general stress-responsive sigma factor on sigmaE-directed cell lysis was investigated. The lysis phenomena were observed in both rpoS mutant and parental strains constitutively expressing active sigmaE, but the former lysis occurred at a relatively early stage compared to the latter. Based on these results and experiments with hydrogen peroxide, we propose that some stresses generate living but non-culturable cells, which are subject to sigmaE-directed cell lysis.