STRUCTURAL CHARACTERIZATION OF ARGINGIPAIN, A NOVEL ARGININE-SPECIFICCYSTEINE PROTEINASE AS A MAJOR PERIODONTAL PATHOGENIC FACTOR FROM PORPHYROMONAS-GINGIVALIS

Argingipain, so termed due to its peptide cleavage specificity at argi nine residue, is a unique extracellular cysteine proteinase produced b y the anaerobic rod Porphyromonas gingivalis, which is known as a majo r pathogenic factor of the progressive periodontal disease (T, Kadowak i, M. Yoneda, K. Okamoto, K. Maeda, and K, Yamamoto (1994) J. Biol, Ch em. 269, 21371-21378), The catalytic specificity and functional import ance of this enzyme prompted us to elucidate its structural features. A DNA fragment for argingipain was selectively amplified by polymerase chain reaction using mixed oligonucleotide primers designed from the NH2-terminal amino acid sequence of the purified enzyme, Although the extracellular mature enzyme was shown to have an apparent molecular ma ss of 44 kDa in gels, the nucleotide sequence of the isolated gene rev ealed a single gene coding for a 109-kDa precursor of argingipain. The deduced amino acid sequence exhibited no significant similarity to th e sequences of representative members of the cysteine protease family. The precursor contained four functional domains: the NH2-terminal sig nal peptide required for the inner membrane transport; the NH2-termina l prosequence, which is assumed to stabilize the precursor structure; the proteinase domain; and the COOH-terminal hemagglutinin domain, whi ch appears to be essential for extracellular secretion of the proteina se domain. Experiments involving the addition of the argingipain inhib itors to the culture medium of P. gingivalis suggested that the matura tion of argingipain occurs intracellularly via an autocatalytic cleava ge of the pro-argingipain propeptide. (C) 1995 Academic Press, Inc.