Affiliation:
1. Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
2. Sidney Kimmel Cancer Center, 10835 Altman Row, San Diego, California 92121
Abstract
ABSTRACT
The invasive pathogen
Salmonella enterica
has evolved a sophisticated device that allows it to enter nonphagocytic host cells. This process requires the expression of
Salmonella
pathogenicity island 1 (SPI-1), which encodes a specialized type III protein secretion system (TTSS). This TTSS delivers a set of effectors that produce a marked rearrangement of the host cytoskeleton, generating a profuse membrane ruffling at the site of interaction, driving bacterial entry. It has been shown that the PhoP/PhoQ two-component system represses the expression of the SPI-1 machinery by down-regulating the transcription of its master regulator, HilA. In this work, we reveal the presence of a PhoP-activated operon within SPI-1. This operon is composed of the
orgB
and
orgC
genes, which encode a protein that interacts with the InvC ATPase and a putative effector protein of the TTSS, respectively. Under PhoP-inducing conditions, expression of this operon is directly activated by the phosphorylated form of the response regulator, which recognizes a PhoP box located at the −35 region relative to the transcription start site. Additionally, under invasion-inducing conditions,
orgBC
expression is driven both by the
prgH
promoter, induced by the SPI-1 master regulator HilA, and by the directly controlled PhoP/PhoQ promoter. Together, these results indicate that in contrast to the rest of the genes encompassed in the SPI-1 locus,
orgBC
is expressed during and after
Salmonella
entry into its host cell, and they suggest a role for the products of this operon after host cell internalization.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
43 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献