VspC from Vibrio splendidus is responsible for collagen degradation in Apostichopus japonicus

Abstract

Vibrio splendidus is a marine opportunistic pathogen that can infect diverse aquaculture animals. In this study, the catalytic domain of the vspC gene, encoding an M9 family metalloproteinase, was cloned from V. splendidus AJ01, and the recombinant catalytic domain rVspC was purified using Ni-NTA agarose. The rVspC can directly degrade collagen collected from body wall as well as the collagen in the coelomocytes of Apostichopus japonicus. Transcriptomics analysis of coelomocytes collected from A. japonicus injected with rVspC showed that there were 52 upregulated genes and 163 downregulated genes, of which the levels of MMP-14 were upregulated while laminin was downregulated in the extracellular matrix. Immune-related pathways of apoptosis, lysosome, phagosome, ubiquitin-mediated proteolysis and antigen processing and presentation were downregulated, while endocytosis was upregulated. Furthermore, one regulatory pathway of “Hfq-SmcR-VspC” at high cell density of V. splendidus was determined. The protein level of SmcR was reduced in Δhfq at high cell density, suggesting that Hfq positively regulates SmcR, and SmcR can bind to the promoters of vspC gene and positively regulates the expression of the vspC gene. In addition, comparative analysis of the sequences of the catalytic domain of VspC revealed that collagenase homologous to VspC are widely present in bacteria, and they may play an important role in colonization, environmental adaptation or virulence in different habitats.