NATURAL VARIATION WITHIN THE PRINCIPAL ARGININE-SPECIFIC PROTEASE GENE, PRPR1, OF PORPHYROMONAS-GINGIVALIS

RI, one of the major extracellular arginine-specific proteases of Porp hyromonas gingivalis is a heterodimer composed of catalytic (alpha) an d adhesin (beta) chains, encoded by the gene prpR1. The distribution o f prpR1 and its variation within 43 isolates of P. gingivalis was dete rmined. Chromosomal DNA was digested with Sma I and probed with a P-32 -labeled DNA fragment from within the coding region for the alpha comp onent of P. gingivalis W50. All isolates gave the expected 3.2 kb band , corresponding to the coding region for the alpha and beta components . The presence of a second locus (prR2) homologous to the alpha region of prpR1 was also detected. The 1.7-kb alpha coding region of prpR1 w as amplified for subsequent restriction analysis. Following Tag I rest riction all isolates gave identical patterns. With Rsa I, the majority of isolates (77%) could be placed into a single group. In conclusion, the prpR1 and prR2 loci are maintained in natural populations of P. g ingivalis, and only minor polymorphism is detectable within the cataly tic domain.