Complementary activities of SseJ and SifA regulate dynamics of the Salmonella typhimurium vacuolar membrane

作者：Javier Ruiz‐Albert, Xiu‐Jun Yu, Carmen R. Beuzón, Abigail N. Blakey, Edouard E. Galyov, David W. Holden · 发表于：Molecular Microbiology · 年份：2002 · DOI：10.1046/j.1365-2958.2002.02912.x · 被引用次数：257 · 研究领域：Vibrio bacteria research studies、Salmonella and Campylobacter epidemiology、Escherichia coli research studies

The Salmonella pathogenicity island 2 (SPI-2) type III secretion system (TTSS) of Salmonella typhimurium is required for bacterial replication within host cells. It acts by translocating effector proteins across the membrane of the Salmonella-containing vacuole (SCV). The SifA effector is required to maintain the integrity of the SCV membrane, and for the formation in epithelial cells of Salmonella-induced filaments (Sifs), which are tubular extensions of SCVs. We have investigated the role in S. typhimurium virulence of the putative SPI-2 effector genes sifB, srfJ, sseJ and sseI. An S. typhimurium strain carrying a mutation in sseJ was mildly attenuated for systemic virulence in mice, but strains carrying mutations in either srfJ, sseI or sifB had very little or no detectable virulence defect after intraperitoneal inoculation. Expression of SseJ in HeLa cells resulted in the formation of globular membranous compartments (GMCs), the composition of which appears to be similar to that of SCV membranes and Sifs. The formation of GMCs was dependent on the serine residue of the predicted acyltransferase/lipase active site of SseJ. Transiently expressed SseJ also inhibited Sif formation by wild-type bacteria, and was found to associate with Sifs, SCV membranes and simultaneously expressed SifA. Intracellular vacuoles containing sseJ mutant bacteria appeared normal but, in contrast to a sifA mutant, a sifA sseJ double mutant strain did not lose its vacuolar membrane, indicating that...