Molecular cloning, expression, purification and functional characterization of an antifungal cyclophilin protein from Panax ginseng .

Cyclophilins (CyPs), a member of peptidyl-prolyl cis-trans isomerases (PPIases), are ubiquitously distributed in organisms such as bacteria, yeast, plants and animals. CyPs have diverse biological functions, with some exhibiting antifungal and antiviral activities. In this study, Panax ginseng cyclophilin ( pgCyP ), a novel gene encoding an antifungal protein from Panax ginseng , was cloned, and its protein product was expressed in Escherichia coli , and then fractionated by affinity chromatography. The open reading frame of the pgCyP full-length coding sequence was found to encode a single-domain CyP-like protein of 174 amino residues with a calculated molecular weight of 18.7 kDa. The pGEX system was used to express pgCyP fused to glutathione S-transferase. After affinity purification, the protein showed a strong fungal resistance effect on Phytophthora cactorum . In addition, pgCyP showed high PPIase activity. To the best of our knowledge, the present study is the first successful effort to clone and characterize a CyP-like protein gene from Panax ginseng .