Cystatin and cystatin-derived peptides have antibacterial activity againstthe pathogen Porphyromonas gingivalis

We investigated whether cystatins and cystatin-derived peptides, encompassi ng sequences of secondary structures of cystatin S and papain binding domai ns of cystatin C, display antimicrobial properties. Of the different microo rganisms tested, only the growth of P. gingivalis was inhibited by chicken cystatin and cystatin C, Cystatin S, cystatin S:1 -14, cystatin S:61 - 73 a nd cystatin S:108 - 121 also inhibited its growth, whereas cystatin S:21-38 , cystatin S:39-55, cystatin S:81-95, cystatin S:94-109, and cystatin C: 9- 12/55-60/106-107 did not. No inhibition of the cysteine proteinase activity of P. gingivalis was observed for all cystatin-derived peptides, On the ot her hand, leupeptin and antipain inhibited P. gingivalis proteinase activit y, but had no effect on the growth. These data suggest that cystatins conta in antibacterial sequences active against P. gingivalis and that the growth inhibition does not depend on the inhibition of P.gingivalis cysteine prot einases.