title: Identification and characterization of a novel serine protease, VvpS, that contains two functional domains and is essential for autolysis of Vibrio vulnificus.
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.
authors.affiliation: National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Moon Sub
authors.initials: MS
authors.lastname: Lim
authors.forename: Jeong-A
authors.initials: JA
authors.lastname: Kim
authors.forename: Jong Gyu
authors.initials: JG
authors.lastname: Lim
authors.forename: Byoung Sik
authors.initials: BS
authors.lastname: Kim
authors.forename: Kwang Cheol
authors.initials: KC
authors.lastname: Jeong
authors.forename: Kyu-Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001433:Bacteriolysis; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D057057:Serine Proteases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014735:Vibrio Infections / Q000382:microbiology; D041261:Vibrio vulnificus / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D057057:Serine Proteases