NUCLEOTIDE AND DEDUCED PROTEIN-SEQUENCE OF THE EXTRACELLULAR, SERINE BASIC PROTEASE GENE (BPRB) FROM DICHELOBACTER-NODOSUS-STRAIN-305 - COMPARISON WITH THE BASIC PROTEASE GENE (BPRV) FROM VIRULENT-STRAIN-198

In earlier studies, it appeared that. benign strains of the Gram-negat ive, obligate anaerobe, Dichelobacter nodosus, were devoid of the extr acellular, serine basic protease (pI approximate to 9.5) of virulent s trains. However, Southern and PCR analysis have shown a homologous gen e (bprB) in the representative benign strain 305. The deduced amino ac id sequence of the prepro- and mature protease regions of bprB confirm ed this homology and showed 97% sequence identity with the bprV precur sor from virulent strain 198. Identity in the carboxy-terminal extensi on region was 90%. Expression studies in Escherichia coli transformed with bprB, showed that the gene was capable of the production of an ac tive protease. A protease, albeit with a lower iso-electric point (app roximate to 8.6), was isolated from D. nodosus culture supernatants an d shown to cross-react with antibodies raised against the more basic p rotease from strain 198. The amino acid sequence encoded by the strain 305 gene revealed two additional acidic residues consistent with a lo wered iso-electric point and supported the conclusion that bprB and bp rV produce equivalent basic proteases.