title: Hemin binding by Porphyromonas gingivalis strains is dependent on the presence of A-LPS.
abstract: Porphyromonas gingivalis is a Gram-negative black pigmenting anaerobe that is unable to synthesize heme [Fe(II)-protoporphyrin IX] or hemin [Fe(III)-protoporphyrin IX-Cl], which are important growth/virulence factors, and must therefore derive them from the host. Porphyromonas gingivalis expresses several proteinaceous hemin-binding sites, which are important in the binding/transport of heme/hemin from the host. It also synthesizes several virulence factors, namely cysteine-proteases Arg- and Lys-gingipains and two lipopolysaccharides (LPS), O-LPS and A-LPS. The gingipains are required for the production of the black pigment, μ-oxo-bisheme {[Fe(III)PPIX]2O}, which is derived from hemoglobin and deposited on the bacterial cell-surface leading to the characteristic black colonies when grown on blood agar. In this study we investigated the role of LPS in the deposition of μ-oxo-bisheme on the cell-surface. A P. gingivalis mutant defective in the biosynthesis of Arg-gingipains, namely rgpA/rgpB, produces brown colonies on blood agar and mutants defective in Lys-gingipain (kgp) and LPS biosynthesis namely porR, waaL, wzy, and pg0129 (α-1, 3-mannosyltransferase) produce non-pigmented colonies. However, only those mutants lacking A-LPS showed reduced hemin-binding when cells in suspension were incubated with hemin. Using native, de-O-phosphorylated and de-lipidated LPS from P. gingivalis W50 and porR strains, we demonstrated that hemin-binding to O-polysaccharide (PS) and to the lipid A moiety of LPS was reduced compared with hemin-binding to A-PS. We conclude that A-LPS in the outer-membrane of P. gingivalis serves as a scaffold/anchor for the retention of μ-oxo-bisheme on the cell surface and pigmentation is dependent on the presence of A-LPS.
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors.forename: M
authors.identifier: 0000-0001-8040-2584
authors.initials: M
authors.lastname: Rangarajan
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Aduse-Opoku
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors.forename: N A
authors.initials: NA
authors.lastname: Paramonov
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.|College of Dentistry, King Faisal University, Al-Ahsa, Saudi Arabia.
authors.forename: A
authors.initials: A
authors.lastname: Hashim
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London, UK.
authors.forename: M A
authors.initials: MA
authors.lastname: Curtis
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D002462:Cell Membrane; D003546:Cysteine Endopeptidases; D000080867:Gingipain Cysteine Endopeptidases; D006418:Heme / Q000378:metabolism; D006427:Hemin / Q000378:metabolism*; D008050:Lipid A / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D016966:Porphyromonas gingivalis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D037521:Virulence Factors
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D008050:Lipid A; D008070:Lipopolysaccharides; D037521:Virulence Factors; D006418:Heme; D006427:Hemin; D003546:Cysteine Endopeptidases
keywords: 
  Porpyhromonas gingivalis
  ; A-LPS; hemin binding; lipopolysaccharides; pigmentation