title: Regulon controlled by the GppX hybrid two component system in Porphyromonas gingivalis.
abstract: The periodontal pathogen Porphyromonas gingivalis experiences a number of environmental conditions in the oral cavity, and must monitor and respond to a variety of environmental cues. However, the organism possesses only five full two-component systems, one of which is the hybrid system GppX. To investigate the regulon controlled by GppX we performed RNA-Seq on a ΔGppX mutant. Fifty-three genes were upregulated and 37 genes were downregulated in the ΔGppX mutant. Pathway analyses revealed no systemic function for GppX under nutrient-replete conditions; however, over 40% of the differentially abundant genes were annotated as encoding hypothetical proteins indicating a novel role for GppX. Abundance of small RNA was, in general, not affected by the absence of GppX. To further define the role of GppX with respect to regulation of a hypothetical protein observed with the greatest significant relative abundance change relative to a wild-type control, PGN_0151, we constructed a series of strains in which the ΔgppX mutation was complemented with a GppX protein containing specific domain and phosphotransfer mutations. The transmembrane domains, the DNA-binding domain and the phosphotransfer residues were all required for regulation of PGN_0151. In addition, binding of GppX to the PGN_0151 promoter regions was confirmed by an electrophoretic mobility shift assay. Both the ΔGppX mutant and a ΔPGN_0151 mutant were deficient in monospecies biofilm formation, suggesting a role for the GppX-PGN_0151 regulon in colonization and survival of the organism.
authors.affiliation: Center for Oral Health and Systemic Disease, School of Dentistry, University of Louisville, Louisville, KY, USA.
authors.forename: T
authors.initials: T
authors.lastname: Hirano
authors.forename: D A C
authors.initials: DA
authors.lastname: Beck
authors.forename: C J
authors.initials: CJ
authors.lastname: Wright
authors.forename: D R
authors.initials: DR
authors.lastname: Demuth
authors.forename: M
authors.initials: M
authors.lastname: Hackett
authors.forename: R J
authors.initials: RJ
authors.lastname: Lamont
mesh_terms: D000483:Alleles; D051777:AraC Transcription Factor / Q000235:genetics; D001224:Aspartic Acid / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D001431:Bacteriological Techniques; D018441:Biofilms / Q000254:growth & development; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D019077:Helix-Turn-Helix Motifs / Q000235:genetics; D000071677:Histidine Kinase; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics; D018085:Regulon / Q000235:genetics*; D017423:Sequence Analysis, RNA; D015398:Signal Transduction / Q000235:genetics
chemical_list: D051777:AraC Transcription Factor; D001426:Bacterial Proteins; C412451:FimR protein, Porphyromonas gingivalis; D008565:Membrane Proteins; D001224:Aspartic Acid; D011494:Protein Kinases; D000071677:Histidine Kinase