Gre factors-mediated control of hilD transcription is essential for the invasion of epithelial cells by Salmonella enterica serovar Typhimurium

PLoS Pathogens

Youssef El Mouali¹  Carlos Balsalobre¹  Tania Gaviria-Cantin¹  Ute Römling²  Soazig Le Guyon² 

[1] Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain;Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden

关键词: Gene expression;    Salmonella typhimurium;    Transcriptional control;    Protein extraction;    Gene regulation;    Epithelial cells;    DNA transcription;    Regulator genes;   

DOI  :  10.1371/journal.ppat.1006312

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The invasion of epithelial cells by Salmonella enterica serovar Typhimurium is a very tightly regulated process. Signaling cascades triggered by different environmental and physiological signals converge to control HilD, an AraC regulator that coordinates the expression of several virulence factors. The expression of hilD is modulated at several steps of the expression process. Here, we report that the invasion of epithelial cells by S. Typhimurium strains lacking the Gre factors, GreA and GreB, is impaired. By interacting with the RNA polymerase secondary channel, the Gre factors prevent backtracking of paused complexes to avoid arrest during transcriptional elongation. Our results indicate that the Gre factors are required for the expression of the bacterial factors needed for epithelial cell invasion by modulating expression of HilD. This regulation does not occur at transcription initiation and depends on the capacity of the Gre factors to prevent backtracking of the RNA polymerase. Remarkably, genetic analyses indicate that the 3’-untranslated region (UTR) of hilD is required for Gre-mediated regulation of hilD expression. Our data provide new insight into the complex regulation of S. Typhimurium virulence and highlight the role of the hilD 3’-UTR as a regulatory motif.

【 授权许可】

CC BY