title: The sinR ortholog PGN_0088 encodes a transcriptional regulator that inhibits polysaccharide synthesis in Porphyromonas gingivalis ATCC 33277 biofilms.
abstract: Biofilm-forming cells are distinct from well characterized planktonic cells and aggregate in the extracellular matrix, the so-called extracellular polymeric substances (EPS). The sinR gene of Bacillus subtilis encodes a transcriptional regulator that is known to be involved in the biosynthesis of EPS in biofilms. Porphyromonas gingivalis inhabits the subgingival and extraradicular biofilm of humans and is one of the primary pathogens that cause progressive marginal and refractory apical periodontitis. Furthermore, P. gingivalis possesses PGN_0088, which encodes a putative ortholog of B. subtilis sinR. Here, we investigated the role of PGN_0088 (sinR) on biofilm formation. P. gingivalis strains formed biofilms on saliva-coated glass surfaces in phosphate buffered saline. Quantitative analysis indicated that the biofilm of the sinR null mutant consisted of dense exopolysaccharide. Microscopic observations showed that the increased levels of exopolysaccharide produced by the sinR mutant changed the morphology of the EPS to a mesh-liked structure. Furthermore, physical analyses suggested that the enrichment of exopolysaccharide in the EPS enhanced the resistance of the biofilm to hydrodynamic shear force. The results presented here demonstrate sinR plays important roles in the ability of P. gingivalis strain ATCC 33277 to act as a negative mediator of exopolysaccharide accumulation and is indirectly associated with the structure of the EPS and the force of its adhesion to surfaces.
authors: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.
authors: Reiko
authors: R
authors: Yamamoto
authors: Yuichiro
authors: Y
authors: Noiri
authors: Mikiyo
authors: M
authors: Yamaguchi
authors: Yoko
authors: Y
authors: Asahi
authors: Hazuki
authors: H
authors: Maezono
authors: Masae
authors: M
authors: Kuboniwa
authors: Mikako
authors: M
authors: Hayashi
authors: Shigeyuki
authors: S
authors: Ebisu
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008855:Microscopy, Electron, Scanning; D009154:Mutation / Q000235:genetics; D011134:Polysaccharides; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011134:Polysaccharides; C076733:FlaD protein, Bacteria