title: Haemin binding as a factor in the virulence of Porphyromonas gingivalis.
abstract: Haemin (iron protoporphyrin IX) is an essential growth factor for the periodontal pathogen. Porphyromonas gingivalis. Iron protoporphyrin IX (IPP IX) binding to the avirulent P. gingivalis beige variant (W50/BE1) and the black-pigmenting parent wild-type strain W50 was quantified. W50/BE1 grown in a chemostat under haemin excess-bound IPP IX under both oxidising and reducing conditions but with both lower capacity and avidity than either the haemin-limited- and haemin-excess-grown parent strain W50. Rosenthal plots for W50/BE1 indicated cooperative binding. W50/BE1 cells expressed a 32 kDa outer membrane haemin-binding protein when grown under conditions of haemin excess, and this strain might serve as a useful source from which to isolate this protein. The reduced IPP IX binding ability of W50/BE1 may be the rate-limiting factor for haem uptake and explain the reduced virulence and slower rate of pigmentation of this strain.
authors.affiliation: Department of Clinical Dental Sciences, University of Liverpool, UK. josmall@liverpool.ac.uk
authors.forename: J W
authors.initials: JW
authors.lastname: Smalley
authors.forename: A J
authors.initials: AJ
authors.lastname: Birss
authors.forename: A S
authors.initials: AS
authors.lastname: McKee
authors.forename: P D
authors.initials: PD
authors.lastname: Marsh
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000737:chemistry / Q000378:metabolism*; D006427:Hemin / Q000378:metabolism*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D016966:Porphyromonas gingivalis / Q000378:metabolism / Q000472:pathogenicity*; D011485:Protein Binding; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D006427:Hemin