An extracellular serine protease produced by Vibrio vulnificus NCIMB 2137, a metalloprotease-gene negative strain isolated from a diseased eel

• DOI: 10.1007/s11274-011-0969-y
• Publication Date: 2011-12-05T08:44:44Z
• Authors: Shin-ichi Miyoshi; Jiyou Wang; Keizo Katoh; Mitsutoshi Senoh; Tamaki Mizuno; Yoko Maehara
• Keywords: DNA, Bacterial; 0303 health sciences; Eels; 572; Molecular Sequence Data; Sequence Analysis, DNA; Chemical Fractionation; Chromatography, Ion Exchange; Polymerase chain reaction; Serine protease; Interspersed Repetitive Sequences; Metalloprotease; 03 medical and health sciences; Genes, Bacterial; Vibrio Infections; Operon; Chromatography, Gel; Animals; Serine Proteases; Vibrio vulnificus; Purification

Vibrio vulnificus is a ubiquitous estuarine microorganism but causes fatal systemic infections in immunocompromised humans, cultured eels or shrimps. An extracellular metalloprotease VVP/VvpE has been reported to be a potential virulence factor of the bacterium; however, a few strains isolated from a diseased eel or shrimp were recently found to produce a serine protease termed VvsA, but not VVP/VvpE. In the present study, we found that these strains had lost the 80 kb genomic region including the gene encoding VVP/VvpE. We also purified VvsA from the culture supernatant through ammonium sulfate fractionation, gel filtration and ion-exchange column chromatography, and the enzyme was demonstrated to be a chymotrypsin-like protease, as well as those from some vibrios. The gene vvsA was shown to constitute an operon with a downstream gene vvsB, and several Vibrio species were found to have orthologues of vvsAB. These findings indicate that the genes vvp/vvpE and vvsAB might be mobile genetic elements.