title: The HA2 haemagglutinin domain of the lysine-specific gingipain (Kgp) of Porphyromonas gingivalis promotes micro-oxo bishaem formation from monomeric iron(III) protoporphyrin IX.
abstract: The lysine- and arginine-specific gingipains (Kgp, and RgpA and RgpB) are the major proteinases produced by the black-pigmented periodontopathogen Porphyromonas gingivalis. They play a role in degrading host proteins, including haemoglobin, from which is formed the mu-oxo bishaem complex of iron(III) protoporphyrin IX, [Fe(III)PPIX]2O, the major haem component of the black pigment. Kgp and RgpA bind haem and haemoglobin via the haemagglutinin-adhesin 2 (HA2) domain, but the role of this domain in the formation of mu-oxo bishaem-containing pigment is not known. UV-visible spectroscopy was used to examine the interaction of iron(III) protoporphyrin IX monomers [Fe(III)PPIX.OH] with recombinant HA2 and purified HRgpA, Kgp and RgpB gingipains. The HA2 domain reacted with Fe(III)PPIX.OH to form mu-oxo bishaem, the presence of which was confirmed by Fourier transform infrared spectroscopy. Both HRgpA and Kgp, but not RgpB, also mediated mu-oxo bishaem formation and aggregation. It is concluded that the Arg- and Lys-gingipains with HA2 haemagglutinin domains may play a crucial role in haem-pigment formation by converting Fe(III)PPIX.OH monomers into [Fe(III)PPIX]2O and promoting their aggregation.
authors.affiliation: The University of Liverpool, Oral Microbiology Group, Department of Clinical Dental Sciences, The Edwards Building, Daulby Street, Liverpool L69 3GN, UK.
authors.forename: J W
authors.initials: JW
authors.lastname: Smalley
authors.affiliation: The University of Liverpool, Oral Microbiology Group, Department of Clinical Dental Sciences, The Edwards Building, Daulby Street, Liverpool L69 3GN, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Birss
authors.affiliation: Department of Microbiology, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Krakow, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Szmigielski
authors.affiliation: Department of Biochemistry and Molecular Biology, Life Science Building, University of Georgia, Athens, GA 30602, USA.|Department of Microbiology, Faculty of Biotechnology, Jagiellonian University, ul. Gronostajowa 7, 30-387 Krakow, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Potempa
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins / Q000737:chemistry / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D006801:Humans; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000378:metabolism*; D011524:Protoporphyrins / Q000378:metabolism*
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins; D011524:Protoporphyrins; C489143:mu-oxo dimeric Fe(III)-protoporphyrin IX; D006418:Heme; C028025:protoporphyrin IX; D003546:Cysteine Endopeptidases