Functional characterization of a type III secretion system effector gene vopR from Vibrio alginolyticus

Abstract

Vibrio alginolyticus is a Gram-negative bacterium widely inhabiting the marine environment and is usually regarded as an opportunistic pathogen. Bacterial pathogenicity is frequently mediated by the type III secretion system (T3SS), which primarily affects vital signaling pathways of host cells. However, the pathogenic mechanism of V. alginolyticus remains unclear. Here, the sequence between the vscL and vscU genes of T3SS was assumed to be the effector coding region. The conserved and diverse effector coding region of T3SS was investigated by comparing the effector coding region of V. alginolyticus HY9901 with that of other T3SS-positive vibrios. Meanwhile, the functional activity of the effector protein VopR of V. alginolyticus HY9901 was reported; the results revealed that the vopR gene is 954 bp in length, encoding 317 amino acids, and has a remarkable similarity to its homologs with other Vibrio species. VopR protein directly binds to Phosphatidic Acid (PA), PtdIns(3,5)P2, and PtdIns(4,5)P2 of the host cell membrane. In vitro experiments demonstrated that the host cell ubiquitination system could be activated by vopR. Meanwhile, vopR could induce apoptosis through the activation of the MKK pathway. This study preliminary investigated the function of V. alginolyticus effector vopR and provided some theoretical basis for further understanding of the pathogenesis of V. alginolyticus.