Construction and characterization of a nonpigmented mutant of Porphyromonas gingivalis: cell surface polysaccharide as an anchorage for gingipains The GenBank/EMBL/DDBJ accession number for the sequences reported in this paper is D64132.

Abstract

A nonpigmented mutant of Porphyromonas gingivalis was constructed by using transposon mutagenesis. The mutant possessed the transposon DNA at the novel gene porR. Gene targeted mutagenesis revealed that porR was responsible for pigmentation. The porR gene shared similarities with genes of the degT family, the products of which are now considered to be transaminases involved in biosynthesis of sugar portions of cell-surface polysaccharides and aminoglycosides. The porR mutant showed a pleiotropic phenotype : delayed maturation of fimbrillin, preferential presence of Rgp and Kgp proteinases in culture supernatants, and no haemagglutination. The porR mutant had altered phenol extractable polysaccharide compared to the porR M sibling strain. A mAb, 1B5, that reacts with sugar portions of P. gingivalis cell surface polysaccharide and membrane-type Rgp proteinase showed no reaction with the cell lysates of the porR mutant. These results indicate that porR is involved in biosynthesis of cell surface polysaccharide that may function as an anchorage for Rgp, Kgp, haemagglutinins and the haemoglobin receptor protein.

Selective Sorting of Cargo Proteins into Bacterial Membrane Vesicles

“…3A). The absence of gingipains in the OM of the waaL Ϫ mutant strain may be a consequence of a defect in gingipain OM anchoring mechanisms, as reported in a porR mutant (26). SDS-PAGE and Western blot analysis of the OM showed equivalent amounts of RagA/B in the four strains (Fig.…”

“…3, A and B, lane 4, and supplemental Table S2). Previously it has been reported that the porR locus is not only required for A-LPS formation but also for gingipain glycosylation and maturation: certain glycan moieties are common to these glycosylated proteases and to A-LPS (15,20,26). If RagA/B were gingipain substrates, the presence of RagA/B in the OMV purified from porS Ϫ and the waaL Ϫ strains might simply reflect reduced gingipain activity in those strains rather than the absence of a specific sorting mechanism.…”

“…We reasoned that a flippase-deficient strain would be useful to determine whether P. gingivalis O antigen chains contribute to OMV formation. The porR locus is involved in A-LPS biosynthesis (15,26); however, not all of the genes in that locus have been characterized (supplemental Fig. S1).…”

Adaptation of Porphyromonas gingivalis to microaerophilic conditions involves increased consumption of formate and reduced utilization of lactate

“…Thus, our findings are significant, as they indicate upregulation of adhesins that in turn facilitate initial adhesion and allow colonization of the oral cavity. On the other hand, PG1138, encoding the major pigmentation and extracellular proteinase activity regulator PorR, was downregulated (Table 2) (Shoji et al, 2002). This regulator has been demonstrated to play a role in modulating the activity of the major group of P. gingivalis proteases, including Rgp and Kgp (Curtis et al, 2001).…”

Importance of heterogeneity in Porhyromonas gingivalis lipopolysaccharide lipid A in tissue specific inflammatory signalling

“…Given that these two virulence factors, independently of each other, can be potent immune effectors in the host, why has P. gingivalis acquired this co-operation with its LPS and Arg gingipains as well? Experiments conducted with deletion mutants in the loci porR (PG1138) and wbpB (PG2119), which are devoid of A-LPS but possess O-LPS [59,60], exerted less gingipain enzymatic activity. These loci are, therefore, probably involved in the biosynthesis of A-LPS [60,61].…”