期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 114, 期 29, 页码 7707-7712出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1700286114
关键词
T6SS; Pseudomonas; RsmA; AmrZ
资金
- Medical Research Council (MRC) [MR/K001930/1, MR/N023250/1]
- Biotechnology and Biological Sciences Research Council (BBSRC) [BB/N002539/1]
- Marie Curie Fellowship [PIIF-GA-2012-328261, PIIF-GA-2013-625318]
- Wellcome Trust
- Imperial College London
- MRC [MR/N023250/1]
- Biotechnology and Biological Sciences Research Council [BB/N002539/1, BB/L007959/1] Funding Source: researchfish
- Engineering and Physical Sciences Research Council [1758883] Funding Source: researchfish
- Medical Research Council [MR/K001930/1, MR/J006874/1, MR/N023250/1] Funding Source: researchfish
- BBSRC [BB/N002539/1, BB/L007959/1] Funding Source: UKRI
- MRC [MR/J006874/1, MR/K001930/1, MR/N023250/1] Funding Source: UKRI
The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1-Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent. However, study of H2-T6SS and H3-T6SS has been neglected because of a poor understanding of the associated regulatory network. Here we performed a screen to identify H2-T6SS and H3-T6SS regulatory elements and found that the posttranscriptional regulator RsmA imposes a concerted repression on all three T6SS clusters. A higher level of complexity could be observed as we identified a transcriptional regulator, AmrZ, which acts as a negative regulator of H2-T6SS. Overall, although the level of T6SS transcripts is fine-tuned by AmrZ, all T6SS mRNAs are silenced by RsmA. We expanded this concept of global control by RsmA to VgrG spike and T6SS toxin transcripts whose genes are scattered on the chromosome. These observations triggered the characterization of a suite of H2-T6SS toxins and their implication in direct bacterial competition. Our study thus unveils a central mechanism that modulates the deployment of all T6SS weapons that may be simultaneously produced within a single cell.
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