vcrV gene affects translocation of T3SS1 effector protein and biological characteristics of Vibrio parahaemolyticus

Abstract:

[Background] vcrV is an important gene located in the T3SS1 gene cluster, which is one of the two sets of type III secretion systems of Vibrio parahaemolyticus and plays a pathogenic role by secreting effector proteins to host cells. [Objective] In this study, the effect of vcrV was explored on the T3SS1 pathogenesis and the biological characteristics of V. parahaemolyticus. [Methods] The vcrV-deleted strain ΔvcrV and the complemented strain CΔvcrV were constructed by homologous recombination technology, using V. parahaemolyticus POR-1 as the reference strain. The growth performance, biofilm formation ability, cell adhesion, and cytotoxicity were compared among different strains. Western Blot was employed to detect the effector proteins secreted by POR-1, ΔvcrV, and CΔvcrV under T3SS1 induction. The translocation of the effector protein VopR (Vp1683) was detected by Western Blot after each strain with the pMMB207-vp1683-CyaA overexpression vector was used to infect HeLa cells. [Results] The deletion of vcrV did not affect the growth performance, biofilm formation ability, or cell adhesion while significantly reduced the strain toxicity to HeLa cells. The effector protein VopR secretion had no significant difference among POR-1, ΔvcrV, and CΔvcrV with the overexpression vector. The translocation of VopR decreased significantly when ΔvcrV infected HeLa cells. [Conclusion] The T3SS1-mediated cytotoxicity involving with vcrV is critical for the translocation of T3SS1 effector protein in V. parahaemolyticus, while the effector protein VopR could still be secreted by ΔvcrV with overexpression vector.