Altered expression and modification of proteases from an avirulent mutant of Porphyromonas gingivalis W50 (W50/BE1)

Microbiology (Reading). 1998 Sep;144 ( Pt 9):2487-96. doi: 10.1099/00221287-144-9-2487.

Abstract

Proteases of Porphyromonas gingivalis are considered to be important factors in the virulence of this organism. A non-pigmenting mutant of P. gingivalis W50 (W50/BE1) has been shown to be less virulent in animal models and to produce significantly less Arg-specific protease activity than the parent strain. Three proteases are present in the culture supernatant of P. gingivalis W50: RI, RIA and RIB. All three proteases are derived from prpR1, which encodes a polypeptide of 1706 amino acids that is organized into distinct domains (pro, alpha, beta and gamma). The aim of the present investigation was to purify and characterize the Arg-specific proteases produced by the avirulent W50/BE1 strain. Significant differences were observed between the proteases of P. gingivalis W50 and W50/BE1. The levels of RI present in the culture supernatant of W50/BE1 were lower than those present in W50, and RIA and RIB were absent. RI from W50/BE1 was composed of three polypeptide chains, unlike the enzyme from W50, which is a heterodimer. The remainder of the Arg-specific protease activity in W50/BE1 was derived from a second gene, prR2, and was present in two fractions, RIIAs/BE (soluble) and RIIAv/BE (vesicle-bound). This activity contained two peptide chains: a approximately 54 kDa chain corresponding to the protease domain and a approximately 26 kDa chain, derived from the propeptide domain of the PrRII precursor. No enzyme with large glycan additions, equivalent to RIB in the vesicle fraction of the wild-type W50, was present. These data indicate that the reduced level of extracellular protease activity in W50/BE1 reflects reduced synthesis and/or export of prpR1 enzymes, which is only partially compensated by synthesis of prR2-derived enzymes, and that all of these proteases undergo altered post-translational modification compared to the parent strain.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Bacterial
  • Arginine / metabolism
  • Bacterial Proteins / immunology
  • Bacterial Proteins / isolation & purification
  • Endopeptidases / genetics*
  • Endopeptidases / immunology
  • Endopeptidases / metabolism*
  • Gene Expression
  • Genes, Bacterial
  • Kinetics
  • Molecular Sequence Data
  • Mutation
  • Porphyromonas gingivalis / enzymology*
  • Porphyromonas gingivalis / genetics
  • Porphyromonas gingivalis / pathogenicity*
  • Protein Processing, Post-Translational
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • Virulence / genetics
  • Virulence / physiology

Substances

  • Antibodies, Bacterial
  • Bacterial Proteins
  • Arginine
  • Endopeptidases