Coaggregation of Porphyromonas gingivalis and Prevotella intermedia

Porphyromonas gingivalis cells coaggregated with Prevotella intermedia cells. The coaggregation was inhibited with L-arginine, L-lysine, N alpha -p-tosyl-L-lysine chloromethyl ketone, trypsin inhibitor, and leupeptin. Heat- and proteinase K-treated P. gingivalis cells showed no coaggregation with P. intermedia cells, whereas heat and proteinase K treatments of P intermedia cells did not affect the coaggregation. The vesicles from P. gingivalis culture supernatant aggregated with P intermedia cells, and this aggregation was also inhibited by addition of L-arginine or L-lysine and by heat treatment of the vesicles. The rgpA rgpB, rgpA kgp, rgpA rgpB kgp, and rgpA kgp hagA mutants of P. gingivalis did not coaggregate with P. intermedia. On the other hand, the fimA mutant lacking the FimA fimbriae showed coaggregation with P intermedia as well as the wild type parent. These results strongly imply that a heat-labile and proteinous factor on the cell surface of P. gingivalis, most likely the gingipain-adhesin complex, is involved in coaggregation of P. gingivalis and P. intermedia.