MicroReview: Envelope stress responses and Gram‐negative bacterial pathogenesis

Abstract

SummaryThe σE, Cpx and Bae envelope stress responses of Escherichia coli are involved in the maintenance, adaptation and protection of the bacterial envelope in response to a variety of stressors. Recent studies indicate that the Cpx and σE stress responses exist in many Gram‐negative bacterial pathogens. The envelope is of particular importance to these organisms because most virulence determinants reside in, or must transit through, this cellular compartment. The Cpx system has been implicated in expression of pili, type IV secretion systems and key virulence regulators, while the σE pathway has been shown to be critical for protection from oxidative stress and intracellular survival. Homologues of the σE– and Cpx‐regulated protease DegP are essential for full virulence in numerous pathogens, and, like σE, DegP appears to confer resistance to oxidative stress and intracellular survival capacity. Some pathogens contain multiple homologues of the Cpx‐regulated, disulphide bond catalyst DsbA protein, which has been demonstrated to play roles in the expression of secreted virulence determinants, type III secretion systems and pili. This review highlights recent studies that indicate roles for the σE, Cpx and Bae envelope stress responses in Gram‐negative bacterial pathogenesis.