Modulation of a thermoregulated type VI secretion system by AHL-dependent Quorum Sensing in Yersinia pseudotuberculosis

Wuhan Institute of Virology, Chinese Academy of Sciences, China.
Archives of Microbiology (Impact Factor: 1.67). 02/2011; 193(5):351-63. DOI: 10.1007/s00203-011-0680-2
Source: PubMed


The type VI secretion system (T6SS) is a novel secretion system found in many Gram-negative bacterial pathogens, which appears to be tightly regulated by different regulatory mechanisms. In the present study, we identified 4 T6SS clusters in Yersinia pseudotuberculosis and demonstrated that they were differentially thermoregulated. Among them, T6SS4 was preferentially expressed at 26°C, and its expression was growth phase dependent and subject to quorum sensing regulation. Both YpsI and YtbI AHL synthases contributed to the positive regulation of T6SS4, whereas YpsI synthase played the major role as T6SS4 expression was reduced strongly in the ypsI mutant strain but weakly in the ytbI mutant strain. Moreover, we provided evidence that exogenous addition of different synthetic AHLs complemented T6SS4 expression in different efficiencies in an ypsIytbI double mutant strain, suggesting C6-HSL had an antagonistic effect on T6SS4 expression. This is the first study demonstrating that the expression of T6SS is precisely regulated by temperature, growth phase, and AHL-dependent quorum sensing systems in Y. pseudotuberculosis.


Available from: Zhi-ming Yuan, Jun 20, 2015
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    • "The PCR product of hcp4-VSV-G was digested with EcoRI/BglII and inserted into the EcoRI/BglII site of pME6032 to generate pME6032- hcp4VSVG. The lacZ fusion reporter vectors pDM4- PT6SS4::lacZ, pDM4-PT6SS1::lacZ, pDM4-PT6SS2::lacZ and pDM4-PT6SS3::lacZ were made previously (Zhang et al., 2011). The reporter vector pDM4-PAR3::lacZ was constructed in a similar manner using primers PAR3-F-SalI/PAR3-R-XbaI. "
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    • "In contrast to their common structure, which is analogous to the injection apparatus of bacteriophages, the specific roles of each of these distinct T6SSs are still obscure: some systems were shown to contribute to the modification of eukaryotic hosts within both pathogenic and symbiotic relationships, while others were linked to inter-bacterial activity during the struggle for niche dominance [61, 62]. All 26 Xanthomonas genomes were searched for the presence of T6SSs using a widely retained T6SS-related protein class (COG3519) as bait [63], which revealed the presence of three distinct T6SSs within the genus (Figure 10). The T6SS of Xf appeared highly similar to one of the two T6SSs that were found in the X. oryzae genomes. "
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    • "Interestingly, hemolysins in Streptococcus agalactiae, a Group B streptococci, have also been shown to induce apoptosis in phagocytic cells (Ulett and Adderson, 2006 and references therein). The yersiniae T6SSs have not been as extensively characterized; however, in Y. psuedotuberculosis, it is regulated by the transcriptional factor OmpR and appears to play a role in stress responses, quorum sensing, and maintenance of internal pH homeostasis (Zhang et al., 2011, 2013; Gueguen et al., 2013). In Y. pestis, the T6SS was found to secrete an Hcp-like autoagglutination factor (Podladchikova et al., 2011). "
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