PMID:21642466

Citation	Lim, MS, Kim, JA, Lim, JG, Kim, BS, Jeong, KC, Lee, KH and Choi, SH (2011) Identification and characterization of a novel serine protease, VvpS, that contains two functional domains and is essential for autolysis of Vibrio vulnificus. J. Bacteriol. 193:3722-32
Abstract	Little is known about the molecular mechanism for autolysis of Gram-negative bacteria. In the present study, we identified the vvpS gene encoding a serine protease, VvpS, from Vibrio vulnificus, a Gram-negative food-borne pathogen. The amino acid sequence predicted that VvpS consists of two functional domains, an N-terminal protease catalytic domain (PCD) and a C-terminal carbohydrate binding domain (CBD). A null mutation of vvpS significantly enhanced viability during stationary phase, as measured by enumerating CFU and differentially staining viable cells. The vvpS mutant reduced the release of cytoplasmic β-galactosidase and high-molecular-weight extracellular chromosomal DNA into the culture supernatants, indicating that VvpS contributes to the autolysis of V. vulnificus during stationary phase. VvpS is secreted via a type II secretion system (T2SS), and it exerts its effects on autolysis through intracellular accumulation during stationary phase. Consistent with this, a disruption of the T2SS accelerated intracellular accumulation of VvpS and thereby the autolysis of V. vulnificus. VvpS also showed peptidoglycan-hydrolyzing activity, indicating that the autolysis of V. vulnificus is attributed to the self-digestion of the cell wall by VvpS. The functions of the VvpS domains were assessed by C-terminal deletion analysis and demonstrated that the PCD indeed possesses a proteolytic activity and that the CBD is required for hydrolyzing peptidoglycan effectively. Finally, the vvpS mutant exhibited reduced virulence in the infection of mice. In conclusion, VvpS is a serine protease with a modular structure and plays an essential role in the autolysis and pathogenesis of V. vulnificus.
Links	PubMed PMC3147509 Online version:10.1128/JB.00314-11
Keywords	Amino Acid Sequence; Animals; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacteriolysis; Gene Expression Regulation, Bacterial; Humans; Mice; Mice, Inbred ICR; Molecular Sequence Data; Protein Structure, Tertiary; Sequence Alignment; Serine Proteases/chemistry; Serine Proteases/genetics; Serine Proteases/metabolism; Vibrio Infections/microbiology; Vibrio vulnificus/enzymology; Vibrio vulnificus/genetics; Vibrio vulnificus/pathogenicity; Vibrio vulnificus/physiology; Virulence
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