title: RpA, an extracellular protease similar to the metalloprotease of serralysin family, is required for pathogenicity of Ralstonia pickettii.
abstract: OBJECTIVE
  To investigate the biochemical and functional properties of an extracellular protease, RpA, in Ralstonia pickettii WP1 isolated from water supply systems.
  
  
  RESULTS
  An extracellular protease was identified and characterized from R. pickettii WP1. A mutant strain WP1M2 was created from strain WP1 by mini-Tn5 transposition. The culture filtrates from WP1M2 had a lower cytotoxic effect than the parental WP1 on several mammalian cell lines. Cloning and sequence analysis revealed the Tn5 transposon inserted at a protease gene (rpA) which is 81% homologous to prtA and aprX genes of Pseudomonas fluorescens. The rpA gene encodes a 482-residue protein showing sequence similarity to metalloproteases of the serralysin family. The RpA protein was expressed in Escherichia coli using a pET expression vector and purified as a 55 kDa molecular weight protein. Furthermore, the protease activity of RpA was inhibited by protease inhibitor and heat treatment.
  
  
  CONCLUSIONS
  The in vitro cytotoxic activity of R. pickettii culture filtrates was attributed to RpA protease.
  
  
  CONCLUSIONS
  An extracellular protease, RpA, was identified from R. pickettii WP1 isolated from water supply system. The RpA metalloproteases is required for the pathogenicity of R. pickettii to mammalian cell lines.
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan.
authors.forename: C-M
authors.initials: CM
authors.lastname: Chen
authors.affiliation: The Institute of Medical Science and Department of Microbiology, China Medical University, Taichung, Taiwan.
authors.forename: J-J
authors.initials: JJ
authors.lastname: Liu
authors.affiliation: Department of Cosmeceutics, College of Pharmacy, China Medical University, Taichung, Taiwan.
authors.forename: C-W
authors.initials: CW
authors.lastname: Chou
authors.affiliation: The Institute of Medical Science and Department of Microbiology, China Medical University, Taichung, Taiwan.
authors.forename: C-H
authors.initials: CH
authors.lastname: Lai
authors.affiliation: The Institute of Medical Science and Department of Microbiology, China Medical University, Taichung, Taiwan.
authors.forename: L-T
authors.initials: LT
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D049920:Ralstonia pickettii / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D016415:Sequence Alignment; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D008666:Metalloendopeptidases; C095666:serralysin
keywords: Ralstonia pickettii WP1; culture filtrates; cytotoxic effect; metalloprotease