The metalloprotease PrtV from Vibrio cholerae

Abstract

Vibrio cholerae, the causative agent of cholera, is a Gram-negative motile bacterial species acquired via ingestion of contaminated food or water. Little is known regarding the environmental survival factors that exist in V. cholerae and play an important role in maximizing the ability of the vibrios to survive and multiply in the environment interacting with predators. In a recent study, we established that Caenorhabditis elegans is useful as a model system for identifying and assessing factors from V. cholerae other than cholera toxin that may contribute to pathogenesis and damage to host organisms [1]. Using reverse molecular genetics techniques, we identified an extracellular protease, the previously uncharacterized PrtV protein, as being necessary for killing of nematodes by V. cholerae [1]. The killing effect is associated with colonization of the C. elegans intestine. The elucidation of mechanisms behind this role for PrtV is of importance for the further understanding of V. cholerae environmental survival and bacteria-host interaction.Tissue barriers to pathogen invasion, such as extracellular matrices, epidermal keratinocyte layers and blood vessel walls, may be targeted by bacterial proteases. Proteolysis of host tissue components, such as extracellular matrix proteins, including collagen, laminin, fibronectin and elastin, could induce necrotic tissue damage [2,3]. Pseudomonas aeruginosa and Serratia mercescens proteases can degrade corneal proteoglycan ground substance and cause keratitis [4,5]. The blood clotting system plays a role in immobilization of invading pathogens and prevention of their dissemination. A pathogen can either use an arsenal of its own proteases, or induce the host fibrinolytic system(s) to dissolve the fibrin clot [6]. Yersinia pestis, the The Vibrio metalloprotease PrtV was purified from the culture supernatant of a Vibrio cholerae derivative that is deficient in several other secreted peptidases, including the otherwise abundant hemagglutinin ⁄ protease HapA. The PrtV is synthesized as a 102 kDa protein, but undergoes several N-and C-terminal processing steps during V. cholerae envelope translocation and prolonged incubation. Purified V. cholerae PrtV protease forms of 81 or 73 kDa were stabilized by calcium ions. Removal of calcium resulted in further rapid autoproteolysis. The two major products of autoproteolysis of the PrtV protease were approximately 37 and 18 kDa and could not be separated under non-denaturing conditions, indicating they are interacting domains. In an assay using cultured cells of the human intestinal cell line HCT8, the PrtV protein showed a cytotoxic effect leading to cell death. Using human blood plasma as a source of potential substrates of mammalian origin for the PrtV protease, we found that the extracellular matrix components fibronectin and fibrinogen were degraded by the enzyme. Additional tests with individual protein substrates revealed that plasminogen was also a possible target for the PrtV protease.OnlineOpen: This article is available fre...

Genomic and proteomic analyses of the coral pathogen Vibrio coralliilyticus reveal a diverse virulence repertoire

“…This protein cleaves host antibacterial proteins. Homologs of the immune inhibitor A, named PrtV, have been found in V. cholerae and V. anguillarum (Vaitkevicius et al, 2006(Vaitkevicius et al, , 2008. PrtV is required for killing C. elegans and has a cytotoxic effect, leading to cell death.…”

A Metalloprotease Secreted by the Type II Secretion System Links Vibrio cholerae with Collagen

“…Bacterial extracellular proteases often undergo multiple proteolytic cleavage steps that lead to the conversion of a pre-proenzyme (an inactive precursor) into a mature protein (44). In V. cholerae, both well-characterized metalloproteases, HapA and PrtV, are subjected to a maturation process that includes several N-and C-terminal modification steps during translocation across the cell envelope and prolonged incubation (45)(46)(47).…”

Evaluation of the vaccine potential of a cytotoxic protease and a protective immunogen from a pathogenic Vibrio harveyi strain

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