THE MOLECULAR-CLONING OF A PHOSPHOLIPASE A(2) FROM BOTHROPS-JARARACUSSU SNAKE-VENOM - EVOLUTION OF VENOM GROUP-II PHOSPHOLIPASE A(2)S MAY IMPLY GENE DUPLICATIONS

The sequence coding for a snake venom phospholipase A(2) (PLA(2)), BJU PLA(2), has been cloned from a Bothrops jararacussu venom gland cDNA l ibrary. The cDNA sequence predicts a precursor containing a 16-residue signal peptide followed by a molecule of 122 amino acid residues with a strong sequence similarity to group II snake venom PLA(2)'s. A stri king feature of the cDNA is the high sequence conservation of the 5' a nd 3' untranslated regions in cDNAs coding for PLA(2)'s from a number of viper species. The greatest sequence variation was observed between the regions coding for the mature proteins, with most substitutions o ccurring in nonsynonymous sites. The phylogenetic tree constructed by alignment of the amino acid sequence of BJUPLA(2) with group II PLA(2) 's in general groups them according to current taxonomical divisions a nd/or functional activity. It also suggests that gene duplications may have occurred at a number of different points during the evolution of snake venom group II PLA(2)'s.