REVISED SEQUENCE OF THE PORPHYROMONAS-GINGIVALIS PRTT CYSTEINE PROTEASE HEMAGGLUTININ GENE - HOMOLOGY WITH STREPTOCOCCAL PYROGENIC EXOTOXIN-B STREPTOCOCCAL PROTEINASE

The prtT gene from Porphyromonas gingivalis ATCC 53977 was previously isolated from an Escherichia coli clone possessing trypsinlike proteas e activity upstream of a region encoding hemagglutinin activity (J, Ot ogoto and H. Kuramitsu, Infect, Immun, 61;117-f23, 1993). Subsequent m olecular analysis of this gene has revealed that the PrtT protein is l arger than originally reported, encompassing the hemagglutination regi o. Results of primer extension experiments indicate that the translati on start site was originally misidentified. An alternate open reading frame of nearly 2.7 kb, which encodes a protein in the size range of 9 6 to 99 kDa, was identified. In vitro transcription-translation experi ments confirm this size, and Northern (RNA) blot experiments indicate that the protease is translated from a 33-kb mRNA. Searching the EMBL protein database revealed that the amino acid sequence of the revised PrtT is similar to sequences of two related proteins from Streptococcu s pyogenes. PrtT is 31% identical and 73% similar over 401 amino acids to streptococcal pyrogenic exotoxin B. In addition, it is 36% identic al and 74% similar over 244 amino acids with streptococcal proteinase, which is closely related to streptococcal pyrogenic exotoxin B. The s imilarity is particularly high at the putative active site of streptoc occal proteinase, which is similar to the active sites of the family o f cysteine proteases. Thus, we conclude that PrtT is a 96- to 99-kDa c ysteine protease and hemagglutinin with significant similarity to stre ptococcal enzymes.