title: Coordinate expression of the Porphyromonas gingivalis lysine-specific gingipain proteinase, Kgp, arginine-specific gingipain proteinase, RgpA, and the heme/hemoglobin receptor, HmuR.
abstract: Heme utilization in Porphyromonas gingivalis requires the participation of an outer membrane hemin/hemoglobin receptor, HmuR, the lysine-specific gingipain proteinase (Kgp) and arginine-specific gingipain proteinase (Rgp). In this study, the expression of hmuR , kgp and rgpA genes in response to growth with different heme sources was examined by reverse transcription-polymerase chain reaction and enzyme-linked immunoassay. Coordinate regulation of hmuR , kgp and rgpA gene expression was evaluated through utilization of P. gingivalis hmuR and kgp mutants or by selective inactivation of proteinases with Kgp- and Rgp-specific inhibitors. We observed that expression of the kgp and rgpA genes was not tightly regulated by heme, but rather by the growth phase. In contrast, expression of the hmuR gene was negatively regulated by heme, while growth of P. gingivalis with human serum resulted in increased hmuR expression. A P. gingivalis kgp isogenic mutant demonstrated significantly increased hmuR gene expression, and inactivation of Kgp and Rgp activity by specific inhibitors up-regulated hmuR gene transcription. Moreover, inactivation of Kgp up-regulated rgpA transcription. Finally, a P. gingivalis hmuR mutant exhibited repressed kgp gene expression and lysine-specific proteinase activity. Collectively, these results indicate that kgp , rgpA and hmuR gene transcription is coordinately regulated and may facilitate greater efficiency of heme utilization in P. gingivalis .
authors.affiliation: Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118, USA.
authors.forename: Xinyan
authors.initials: X
authors.lastname: Liu
authors.forename: Aneta
authors.initials: A
authors.lastname: Sroka
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
authors.forename: Caroline Attardo
authors.initials: CA
authors.lastname: Genco
mesh_terms: D018829:Adhesins, Bacterial; D003546:Cysteine Endopeptidases / Q000378:metabolism* / Q000502:physiology; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins / Q000378:metabolism* / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism*; D016966:Porphyromonas gingivalis / Q000201:enzymology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins; D006454:Hemoglobins; D011956:Receptors, Cell Surface; C028027:heme receptor; D003546:Cysteine Endopeptidases