Porphyromonas gingivalis Mutant Defective in a Putative Glycosyltransferase Exhibits Defective Biosynthesis of the Polysaccharide Portions of Lipopolysaccharide, Decreased Gingipain Activities, Strong Autoaggregation, and Increased Biofilm Formation

• Published in: Infection and Immunity Vol. 78; no. 9; pp. 3801 - 3812
• Main Authors: Yamaguchi, Mikiyo, Sato, Keiko, Yukitake, Hideharu, Noiri, Yuichiro, Ebisu, Shigeyuki, Nakayama, Koji
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.09.2010; American Society for Microbiology (ASM)
• Subjects: Adhesins, Bacterial - analysis; Adhesins, Bacterial - physiology; Biofilms; Cysteine Endopeptidases - analysis; Cysteine Endopeptidases - physiology; DNA Transposable Elements; Glycosyltransferases - physiology; Lipopolysaccharides - analysis; Lipopolysaccharides - biosynthesis; Lipopolysaccharides - chemistry; Microscopy, Electron, Scanning; Molecular Pathogenesis; Mutation; Porphyromonas gingivalis; Porphyromonas gingivalis - physiology
• ISSN: 0019-9567; 1098-5522
• DOI: 10.1128/IAI.00071-10

The Gram-negative anaerobic bacterium Porphyromonas gingivalis is a major pathogen in periodontal disease, one of the biofilm-caused infectious diseases. The bacterium possesses potential virulence factors, including fimbriae, proteinases, hemagglutinin, lipopolysaccharide (LPS), and outer membrane vesicles, and some of these factors are associated with biofilm formation; however, the precise mechanism of biofilm formation is still unknown. Colonial pigmentation of the bacterium on blood agar plates is related to its virulence. In this study, we isolated a nonpigmented mutant that had an insertion mutation within the new gene PGN_1251 (gtfB) by screening a transposon insertion library. The gene shares homology with genes encoding glycosyltransferase 1 of several bacteria. The gtfB mutant was defective in biosynthesis of both LPSs containing O side chain polysaccharide (O-LPS) and anionic polysaccharide (A-LPS). The defect in the gene resulted in a complete loss of surface-associated gingipain proteinases, strong autoaggregation, and a marked increase in biofilm formation, suggesting that polysaccharide portions of LPSs influence attachment of gingipain proteinases to the cell surface, autoaggregation, and biofilm formation of P. gingivalis.