cDNA and protein sequences coding for the precursor of phospholipase A2 from Taiwan cobra, Naja naja atra

The cDNA sequence encoding phospholipase A2 (PLA2) was determined by analysis of polymerase-chain-reaction (PCR) product amplified from total cDNA mixture which had been constructed from the poly(A)+RNA of venom glands obtained from Taiwan cobras. Two oligonucleotide segments corresponding to the 5'- and 3'-noncoding regions of sea-snake PLA2 gene were used as primers for PCR-amplified reaction. Plasmids of transformed E. coli strain JM109 containing amplified PLA2 cDNA were purified and prepared for nucleotide sequencing by dideoxynucleotide chain-termination method. Sequencing more than five clones containing about 0.5 kb DNA inserts revealed two isoforms with complete reading frames of 468 base pairs each covering a precursor for phospholipase A2 with a deduced mature protein sequence of 119 amino acids and a 27 amino-acid signal peptide. These two enzymes of Group I PLA2 differ in six nucleotide residues at the gene level and three amino acids along the whole polypeptide chain, each consisting of 14 cysteine residues similar to all reported PLA2 of different snake venoms. The signal peptides and hydropathy profiles of Group I PLA2 reported here are distinctly different from those of Group II PLA2 in viperid snakes.