The Effect of the Lysine Acetylation Modification of ClpP on the Virulence of Vibrio alginolyticus

Acetylation modification has become one of the most popular topics in protein post-translational modification (PTM) research and plays an important role in bacterial virulence. A previous study indicated that the virulence-associated caseinolytic protease proteolytic subunit (ClpP) is acetylated at the K165 site in <i>Vibrio alginolyticus</i> strain HY9901, but its regulation regarding the virulence of <i>V. alginolyticus</i> is still unknown. We further confirmed that ClpP undergoes lysine acetylation (Kace) modification by immunoprecipitation and Western blot analysis and constructed the complementation strain (C-<i>clpP</i>) and site-directed mutagenesis strains including K165Q and K165R. The K165R strain significantly increased biofilm formation at 36 h of incubation, and K165Q significantly decreased biofilm formation at 24 h of incubation. However, the acetylation modification of ClpP did not affect the extracellular protease (ECPase) activity. In addition, we found that the virulence of K165Q was significantly reduced in zebrafish by in vivo injection. To further study the effect of lysine acetylation on the pathogenicity of <i>V. alginolyticus</i>, GS cells were infected with four strains, namely HY9901, C-<i>clpP</i>, K165Q and K165R. This indicated that the effect of the K165Q strain on cytotoxicity was significantly reduced compared with the wild-type strain, while K165R showed similar levels to the wild-type strain. In summary, the results of this study indicate that the Kace of ClpP is involved in the regulation of the virulence of <i>V. alginolyticus</i>.