title: Porphyromonas gingivalis cysteine proteinase inhibition by kappa-casein peptides.
abstract: Porphyromonas gingivalis is a major pathogen associated with chronic periodontitis, an inflammatory disease of the supporting tissues of the teeth. The Arg-specific (RgpA/B) and Lys-specific (Kgp) cysteine proteinases of P. gingivalis are major virulence factors for the bacterium. In this study κ-casein(109-137) was identified in a chymosin digest of casein as an inhibiting peptide of the P. gingivalis proteinases. The peptide was synthesized and shown to inhibit proteolytic activity associated with P. gingivalis whole cells, purified RgpA-Kgp proteinase-adhesin complexes, and purified RgpB proteinase. The peptide κ-casein(109-137) exhibited synergism with Zn(II) against both Arg- and Lys-specific proteinases. The active region for inhibition was identified as κ-casein(117-137) using synthetic peptides. Kinetic studies revealed that κ-casein(109-137) inhibits in an uncompetitive manner. A molecular model based on the uncompetitive action and its synergistic ability with Zn(II) was developed to explain the mechanism of inhibition. Preincubation of P. gingivalis with κ-casein(109-137) significantly reduced lesion development in a murine model of infection.
authors.affiliation: Oral Health Cooperative Research Centre, Melbourne Dental School, The University of Melbourne, 720 Swanston Street, Victoria 3010, Australia.
authors.forename: Elena C Y
authors.initials: EC
authors.lastname: Toh
authors.forename: Stuart G
authors.initials: SG
authors.lastname: Dashper
authors.forename: N Laila
authors.initials: NL
authors.lastname: Huq
authors.forename: Troy J
authors.initials: TJ
authors.lastname: Attard
authors.forename: Neil M
authors.initials: NM
authors.lastname: O'Brien-Simpson
authors.forename: Yu-Yen
authors.initials: YY
authors.lastname: Chen
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Cross
authors.forename: David P
authors.initials: DP
authors.lastname: Stanton
authors.forename: Rita A
authors.initials: RA
authors.lastname: Paolini
authors.forename: Eric C
authors.initials: EC
authors.lastname: Reynolds
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D002364:Caseins / Q000737:chemistry*; D057056:Cysteine Proteases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000201:enzymology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002364:Caseins; D015853:Cysteine Proteinase Inhibitors; D010455:Peptides; D057056:Cysteine Proteases