Host Defense Peptides In Skin Secretions Of Odorrana Tiannanensis: Proof For Other Survival Strategy Of The Frog Than Merely Anti-microbial

Genus Odorrana, among all amphibians studied, is generally reported to have the mostabundant and diversified anti-microbial peptides even from a single individual frog. In ourprevious work,46cDNA sequences encoding precursors of22different anti-microbialpeptides (AMPs) were characterized from the skin of frog Odorrana tiannanensis. In thiswork, we reported the purification of three AMPs from skin secretions of O. tiannanensis.Their amino acid sequences matched well with the sequences deduced from cDNAs and theywere designated as Odorranain-C7HSa, Brevinin-1-OT2and Odorranain-G-OT, respectively.Furthermore, we selected to analyze the four most structurally diversified sequences amongthe22AMPs that are significantly different fromall reported AMPs. By structuralcharacterization, three of them were designated as pleurain-E-OT,odorranain-G-OT,odorranain-A-OT, belonging to AMP families already identified. The forth one with a unique14-mer sequence of AILTTLANWARKFL and C-terminal amidation represents the prototypesof a new class of amphibian AMP, and thereby named tiannanensin. Such broad diversity insequences and structures are consistent with other species in Genus Odorrana. Multi-functionsof the synthesized four special AMPs were screened, including anti-microbial, antioxidant,cytotoxic and hemolytic activities. The results suggest that these AMPs may employsophisticated mechanisms of action in host defense in addition to anti-microbial,although theirprecise contribution to host defense still seems unclear.