A family of bombinin-related peptides from the skin of Bombina variegata.

A peptide fraction was isolated from the skin of Bombina variegata that showed antimicrobial activity. This fraction contained several molecular species, all of them consisting of 27 amino acid residues, with a constant C-terminal region (from residues 14-27), including an amidated carboxyl end and a variable N-terminal segment. These peptides are related but not identical to bombinin [Csordas, A. & Michl, H. (1970) Monatsh. Chem. 101, 182-189]. By using synthetic oligonucleotides corresponding to the C-terminal region of the peptides, a cDNA library from the skin of B. variegata was screened and several positive clones coding for the corresponding peptide precursors were isolated and sequenced. Each clone contained the genetic information for a different bombinin-like peptide. The antimicrobial activity towards different bacterial species of a synthetic peptide corresponding to one of the variants deduced from cDNA sequences was tested. This peptide was found to be mainly active against different isolates of Staphylococci and Escherichia coli.