Defensins in snakes: antibiotic activity and comparative genomic analysis

Abstract

This project proceeds the work developed by the group (FAPESP 1999/02675-6, 2004/09664-0, 2008/55469-5). The results obtained were the sequence of crotamine and crotasin genes, the relationship between the crotamine concentration in venom and the gene copy number, as well the antibiotic activity of crotamine. The crotamine is a myotoxin from the venom of Crotalus durissus terrificus rattlesnake and the crotasin, a gene highly expressed in the liver and spleen of the same animal. Both have beta-defensin structure, a group of antimicrobial peptides. Several defensins of vertebrates were discovered using PCR, as they have in common a signal peptide and 3'-untranslated (3'-UTR), despite the variation in amino acid sequence of the mature defensin. This characteristic was also observed to crotamine and crotasin nucleotide sequences. Descriptions of defensin genes in snakes as well as its validation through tests of antibiotic activity are important in comparative genomic analysis of this gene family. The information will permit analyzing the genes in evolutionary context and determine whether we can use these sequences for snake phylogeny. The description of new defensins includes the confirmation of its antibiotic activity. To install this methodology in our laboratory, we will use the crotasin recombinant as a model. Beside the study of genes of defensins in the genus Bothrops, we will also analyze the venom polymorphism in other species such as B. atrox using two-dimensional gel and Western blotting for the major components, the metallo and serine proteases. (AU)