ANTIMICROBIAL PEPTIDES FROM SKIN SECRETIONS OF RANA-ESCULENTA - MOLECULAR-CLONING OF CDNAS ENCODING ESCULENTIN AND BREVININS AND ISOLATION OF NEW ACTIVE PEPTIDES

Three cytolytic peptides, termed brevinin-1E, brevinin-2E, and esculen tin, were isolated from skin secretions of the European frog Rana escu lenta (Simmaco, M., Mignogna, G., Barra, D., and Bossa, F. (1993) FEBS Lett. 324, 159-161). Nucleotide sequence analysis of cDNAs coding for the corresponding precursors revealed that in all of them a single co py of the sequence of the mature peptide is present preceded by a diba sic cleavage site and followed by a stop codon. The signal peptides of these precursors show a clear homology to the corresponding region of the precursor of dermorphin, a neuropeptide occurring in the skin of amphibians of the subfamily Phyllomedusinae. Ten new peptides, ranging in size from 24 to 46 residues, all possessing an intramolecular disu lfide bridge located at the carboxyl-terminal end, were isolated from skin secretions of R. esculenta. These peptides can be grouped into fo ur subfamilies on the basis of their distinctive structural and/or fun ctional properties. All of these new peptides have antimicrobial and/o r hemolytic activities typical for the respective subfamily. In additi on, we demonstrate that esculentin-1 also inhibits the growth of Pseud omonas aeruginosa, Candida albicans, and Saccharomyces cerevisiae.