title: Gingipain enzymes from Porphyromonas gingivalis preferentially bind immobilized extracellular proteins: a mechanism favouring colonization?
abstract: OBJECTIVE
  Porphyromonas gingivalis, an anaerobic bacterium associated with adult periodontal disease, employs a number of pathogenic mechanisms, including protease/adhesin complexes (gingipains), fimbriae and hemagglutinins, to maintain attachment within colonized hosts. Here we examined the binding of gingipains and whole, live P. gingivalis cells to immobilized extracellular matrix proteins in the presence of soluble forms of the same proteins, to investigate whether this may constitute a colonization mechanism in the oral environment.
  
  
  METHODS
  Binding of purified gingipain molecules and whole bacterial cells to immobilized matrix proteins was examined in the presence and absence of soluble competitors using enzyme-linked immunosorbent assays.
  
  
  RESULTS
  Purified gingipains or whole, live bacteria preferentially bound immobilized forms of matrix proteins, even in the presence of soluble forms of the same proteins. Fimbriae appeared to be redundant for adhesion to immobilized proteins in the presence of the gingipains, indicating that the protease/adhesins and hemagglutinins may be more important for adhesion under these conditions.
  
  
  CONCLUSIONS
  The data presented here provide evidence for a model of adhesion for P. gingivalis within the fluid environment of the oral cavity, where preferential binding of matrix-located proteins over soluble forms facilitates colonization of the host.
authors.affiliation: Department of Biochemistry and Molecular Biology and CRC for Oral Health Sciences, Monash University, Clayton, Vic., Australia.
authors.forename: A D
authors.initials: AD
authors.lastname: McAlister
authors.forename: A
authors.initials: A
authors.lastname: Sroka
authors.forename: R E
authors.initials: RE
authors.lastname: Fitzpatrick
authors.forename: N S
authors.initials: NS
authors.lastname: Quinsey
authors.forename: J
authors.initials: J
authors.lastname: Travis
authors.forename: J
authors.initials: J
authors.lastname: Potempa
authors.forename: R N
authors.initials: RN
authors.lastname: Pike
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D001422:Bacterial Adhesion / Q000502:physiology*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D036781:Fimbriae Proteins; D000080867:Gingipain Cysteine Endopeptidases; D006801:Humans; D055767:Immobilized Proteins / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000201:enzymology*; D011485:Protein Binding; D019096:Vitronectin / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D000080867:Gingipain Cysteine Endopeptidases; D055767:Immobilized Proteins; D019096:Vitronectin; D036781:Fimbriae Proteins; D005340:Fibrinogen; D003546:Cysteine Endopeptidases