4 NEW POSTSYNAPTIC NEUROTOXINS FROM NAJA-NAJA-SPUTATRIX VENOM - CDNA CLONING, PROTEIN EXPRESSION, AND PHYLOGENETIC ANALYSIS

cDNAs encoding 4 short chain alpha-neurotoxins from Malayan spitting c obra (Naja naja sputatrix) venom were cloned and expressed in Escheric hia toll. The recombinant toxins possessed identical amino acid sequen ces to alpha-neurotoxins. This is the first report on cloning and expr ession of isoforms of neurotoxins from a species of spitting cobra. Tw o of these isoforms were also identified in the crude venom by reverse phase-high performance liquid chromatography (RP-HPLC), capillary ele ctrophoresis followed by mass spectrometry and characterized by protei n sequencing. Based on the variable amino acid residues, the neurotoxi ns in N. n. sputatrix could be assigned to 2 major groups, (ET)-E-10-T -11 and (10)Q(11)A, which could be further subdivided into (ETS)-E-10- T-11-S-28; (10)E(11)T(28)G and (10)Q(11)A(28)S; (10)Q(11)A(28)G respec tively. These substitutions were also found to be unique to N. n. sput atrix neurotoxins. Phylogenetic analysis based on molecular properties of the toxins provided further support for the classification of N. n . sputatrix neurotoxin into 2 fundamental groups. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.