Subtilisin-like protease-1 secreted through type IV secretion system contributes to high virulence of Streptococcus suis 2.

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Subtilisin-like protease-1 secreted through type IV secretion system contributes to high virulence of Streptococcus suis 2.

Sci Rep. 2016 06 08;6:27369

Authors: Yin S, Li M, Rao X, Yao X, Zhong Q, Wang M, Wang J, Peng Y, Tang J, Hu F, Zhao Y

Abstract
Streptococcus suis serotype 2 is an emerging zoonotic pathogen that triggered two outbreaks of streptococcal toxic shock syndrome (STSS) in China. Our previous research demonstrated that a type IV secretion system (T4SS) harbored in the 89K pathogenicity island contributes to the pathogenicity of S. suis 2. In the present study, a shotgun proteomics approach was employed to identify the effectors secreted by T4SS in S. suis 2, and surface-associated subtilisin-like protease-1 (SspA-1) was identified as a potential virulence effector. Western blot analysis and pull-down assay revealed that SspA-1 secretion depends on T4SS. Knockout mutations affecting sspA-1 attenuated S. suis 2 and impaired the pathogen's ability to trigger inflammatory response in mice. And purified SspA-1 induced the secretion of IL-6, TNF-α, and IL-12p70 in THP-1 cells directly. SspA-1 is the first T4SS virulence effector reported in Gram-positive bacteria. Overall, these findings allow us to gain further insights into the pathogenesis of T4SS and STSS.

PMID: 27270879 [PubMed - indexed for MEDLINE]

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