YgaE Regulates Out Membrane Proteins inSalmonella entericaSerovar Typhi under Hyperosmotic Stress

Abstract

Salmonella entericaserovar Typhi (S. Typhi) is a human-specific pathogen that causes typhoid fever. In this study, we constructedΔygaEmutant and a microarray was performed to investigate the role ofygaEin regulation of gene expression changes in response to hyperosmotic stress inS. Typhi. qRT-PCR was performed to validate the microarray results. Our data indicated thatygaEwas the repressor ofgaboperon inS. Typhi as inEscherichia coli(E. coli), though the sequence ofygaEis totally different fromgabC(formerlyygaE) inE. coli. OmpF, OmpC, and OmpA are the most abundant out membrane proteins inS. Typhi. Here we report that YgaE is a repressor of both OmpF and OmpC at the early stage of hyperosmotic stress. Two-dimensional electrophoresis was applied to analyze proteomics of total proteins in wild-type strain andΔygaEstrain and we found that YgaE represses the expression of OmpA at the late stage of hyperosmotic stress. Altogether, our results implied that YgaE regulates out membrane proteins in a time-dependent manner under hyperosmotic stress inS. Typhi.