MULTIPLE COLONIZATION DEFECTS IN A CYSTEINE PROTEASE MUTANT OF PORPHYROMONAS-GINGIVALIS

A cysteine protease mutant, G-102, of Porphyromonas gingivalis 381 def ective in the rqp-1 gene has been recently constructed in this laborat ory. In order to evaluate the role of the protease in the virulence pr operties of P. gingivalis, a number of putative periodontopathic prope rties of the mutant were evaluated. Relative to the parental strain, m utant G-102 was demonstrated to be defective in interacting with Gram- positive bacteria as well as cultured epithelial cells. In addition, t he mutant was altered in attaching to the protein components of extrac ellular matrix as well as to type I collagen. Some of these alteration s could result from the decreased autoaggregation displayed by mutant G-102 relative to strain 381. However, since the epithelial cell attac hment assays were carried out at very low bacterial densities, it is u nlikely that reduced autoaggregation of the mutant is responsible for its decreased ability to attach to these eucaryotic cells. Electron mi croscopic examination of The cells also revealed that mutant G-102 was altered in normal fimbrae expression. In addition, reduced expression of the 43 kDa fimbrial subunit in the mutant was detected with both W estern and Northern blotting. These results indicated that the rgp-1 g ene product can play either a direct or indirect role in the colonizat ion properties of P. gingivalis.