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

Abstract

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 Porphyromonas gingivalis is a major pathogen in severe forms of periodontal disease and refractory periapical perodontitis (28,39). This Gram-negative anaerobic bacterium possesses several virulence factors, including fimbriae, proteinases, hemagglutinin, lipopolysaccharide (LPS), and outer membrane vesicles (7,13,16,27). P. gingivalis forms black-pigmented colonies on blood agar plates. Colonial pigmentation is caused by accumulation of -oxo heme dimer on the cell surface (58). Nonpigmented mutants of P. gingivalis have been isolated and characterized by a number of researchers (5,17,51,56,(62)(63)(64). Colonial pigmentation on blood agar plates has been shown to be linked with hemagglutination and activities of major proteinases, Arggingipain (Rgp) and Lys-gingipain (Kgp), and other virulence factors, suggesting that colonial pigmentation is associated with the presence of gingipain-adhesin complexes on the cell surface (3,11,60).Pigmentation-related genes that have been characterized are classified into three categories: gene expression, membrane translocation, and surface attachment of gingipain-adhesin complexes (51). Gingipain-adhesin complexes comprise Rgp and Kgp proteinases encoded by rgpA, rgpB, and kgp and adhesins encoded by rgpA, kgp, and hagA. kgp single and rgpA rgpB kgp triple mutants form less-and nonpigmented colonies, respectively, whereas an rgpA rgpB double mutant forms pigmented colonies (42, 55). Smalley et al. (59) found that Rgp activity is crucial for converting oxyhemoglobin into the methemoglobin form, which is rendered more susceptible to Kgp degradation for the eventual release of iron(III) protoporphyrin IX and production of -oxo heme dimer. A defect in membrane translocation of gingipain-adhesin complexes causes nonpigmentation. The three genes porT, sov, and PG0027, mutants of which exhibit nonpigmentation, have been reported to be involved in membrane translocation of gingipain-adhesin complexes (18,49,53). High-molecularweight forms of Rgp, Kgp, and adhesins accumulate in the periplasmic space of those mutants (49,53). Very recently, we found a novel protein secretion system, the Por secretion system (PorSS), mediating secretion for gingipain-adhesin complexes, and the porK, porL, porM, porN, porP, porQ, porU, porW, porX, and porY genes have been added to this category (52).

VimA-Dependent Modulation of Acetyl Coenzyme A Levels and Lipid A Biosynthesis Can Alter Virulence in Porphyromonas gingivalis

“…Several genes, including porR, gftB, rfa, ugdA, vimE, and vimF, have shown the importance of the O side chain polysaccharide (O-LPS) and anionic polysaccharide (A-LPS) in these processes (50,53,(61)(62)(63)66). A defect in some of these genes resulted in a complete loss of surface-associated gingipain proteinases, strong autoaggregation, and a marked increase in biofilm formation.…”

Using Tn-seq To Identify Pigmentation-Related Genes of Porphyromonas gingivalis: Characterization of the Role of a Putative Glycosyltransferase

“…Journal of Bacteriology the putative glycosyltransferase may modify LPS structure and thereby affect pigmentation and gingipain activity (18,19). We employed three different methods to analyze lipopolysaccharide.…”

Inhibition of polysaccharide synthesis by the sinR orthologue PGN_0088 is indirectly associated with the penetration of Porphyromonas gingivalis biofilms by macrolide antibiotics

“…All bacterial strains used in this study are listed in Table 1. Similar to our previous studies (Yamaguchi et al, 2010;Yamamoto et al, 2011Yamamoto et al, , 2013, P. gingivalis cells were grown anaerobically (10 % CO 2 , 10 % H 2 and 80 % N 2 ) in Gifu anaerobic medium (GAM; Nissui) on Soybean-Casein-Digest agar (SCD agar; Nissui). For selection and maintenance of antibioticresistant strains, antibiotics were added to the medium at concentrations as follows: 100 mg ampicillin ml 21 ; 20 mg chloramphenicol ml 21 ; 200 mg gentamicin ml 21 ; or 0.7 mg tetracycline ml 21 .…”