H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing

The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium,...

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Bibliographic Details
Published in:Infection and immunity 2015-07, Vol.83 (7), p.2738-2750
Main Authors: Brunet, Yannick R, Khodr, Ahmad, Logger, Laureen, Aussel, Laurent, Mignot, Tâm, Rimsky, Sylvie, Cascales, Eric
Format: Article
Language:English
Subjects:
Animals
Artificial Gene Fusion
Bacterial Proteins - metabolism
Bacterial Secretion Systems
Bacterial Toxins - metabolism
Biochemistry, Molecular Biology
Cellular Biology
DNA Footprinting
DNA-Binding Proteins - metabolism
Electrophoretic Mobility Shift Assay
Environmental Sciences
Gene Expression Regulation, Bacterial
Gene Silencing
Genes, Reporter - genetics
Genetics
Genomic Islands
Life Sciences
Microscopy, Fluorescence
Molecular Pathogenesis
Salmonella enterica
Salmonella typhimurium
Salmonella typhimurium - genetics
Salmonella typhimurium - pathogenicity
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Summary:The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection.
ISSN:0019-9567
1098-5522
DOI:10.1128/IAI.00198-15