Molecular Cloning and Sequence Analysis of the cDNA for Metalloproteinase from the Venom of Agkistrodon Acutus

Total RNA was extracted from the venom glands of Agkistrodon acutus. The cDNA for one type of low molecular weight metalloproteinase(aculysinl)was amplified by RT PCR and cloned into the pGEMT vector.Its cDNA sequence was determined.The cDNA sequence with 1 290 bp encodes an open reading frame(ORF) of 417 amino acids,which included a signal peptide of 18 amino acids,a proposed propeptide of 171 amino acids,a mature protein of 203 amino acids and a spacer of 25 amino acids.Aculysinl was synthesized as a prozymogen which was modified post translationally.The aculysinl propeptide had a “cysteine switch”motif(HKICGVT) which was different from that (PKMCGVT)involved in the activation of metalloproteinase prozymogens.Aculysinl exhibited a definite amino acid homology (49%-63%) to other metalloproteinases from the snake venoms.Like other metalloproteinases,it also had a conserved zinc bindng domain(HEXXHXXGXXH).There are 6 cysteine residues in aculysinl which forms 3 disulfide bonds.The successful cloning of the cDNA for the metalloproteinase from Agkistrodon acutus lays a good foundation for the study of structure function relationships of snake venom metalloproteinases and for the development of the clinical medicines to cure the thrombotic diseases.