Back to Search Start Over

The transcriptional regulator SsrB is involved in a molecular switch controlling virulence lifestyles of Salmonella.

Authors :
Deyanira Pérez-Morales
María M Banda
N Y Elizabeth Chau
Heladia Salgado
Irma Martínez-Flores
J Antonio Ibarra
Bushra Ilyas
Brian K Coombes
Víctor H Bustamante
Source :
PLoS Pathogens, Vol 13, Iss 7, p e1006497 (2017)
Publication Year :
2017
Publisher :
Public Library of Science (PLoS), 2017.

Abstract

The evolution of bacterial pathogenicity, heavily influenced by horizontal gene transfer, provides new virulence factors and regulatory connections that alter bacterial phenotypes. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) are chromosomal regions that were acquired at different evolutionary times and are essential for Salmonella virulence. In the intestine of mammalian hosts, Salmonella expresses the SPI-1 genes that mediate its invasion to the gut epithelium. Once inside the cells, Salmonella down-regulates the SPI-1 genes and induces the expression of the SPI-2 genes, which favor its intracellular replication. The mechanism by which the invasion machinery is deactivated following successful invasion of host cells is not known. Here, we show that the SPI-2 encoded transcriptional regulator SsrB, which positively controls SPI-2, acts as a dual regulator that represses expression of SPI-1 during intracellular stages of infection. The mechanism of this SPI-1 repression by SsrB was direct and acts upon the hilD and hilA regulatory genes. The phenotypic effect of this molecular switch activity was a significant reduction in invasion ability of S. enterica serovar Typhimurium while promoting the expression of genes required for intracellular survival. During mouse infections, Salmonella mutants lacking SsrB had high levels of hilA (SPI-1) transcriptional activity whereas introducing a constitutively active SsrB led to significant hilA repression. Thus, our results reveal a novel SsrB-mediated mechanism of transcriptional crosstalk between SPI-1 and SPI-2 that helps Salmonella transition to the intracellular lifestyle.

Details

Language :
English
ISSN :
15537366 and 15537374
Volume :
13
Issue :
7
Database :
Directory of Open Access Journals
Journal :
PLoS Pathogens
Publication Type :
Academic Journal
Accession number :
edsdoj.90fab0b1da5e49e3b1a7b6973185e01c
Document Type :
article
Full Text :
https://doi.org/10.1371/journal.ppat.1006497