Molecular cloning, characterization and evolution of the gene encoding a new group of short-chain alpha-neurotoxins in an Australian elapid, Pseudonaja textilis

The structure and organization of five genes responsible for the synthesis of six isoforms of short-chain alpha-neurotoxins in Pseudonaja textilis ven om are reported in this paper. This also forms the first report which descr ibes the synthesis of two neurotoxin mRNA variants from one of these genes (Pt-sntx1) as a result of alternative splicing. Each gene consists of three exons which are separated by two introns and each has a functional promote r. The promoter activity was confirmed by both CAT assay and Real-Time PCR, A transcription initiation site, two putative TATA boxes, one CCAAT box an d the transcription factor binding consensus sites for AP-1, GATA-2, c/EBPb were identified in the 5' non-coding region of each gene. Phylogenetic ana lysis shelved that these five genes from P. textilis constituted a distinct group which has evolved by gene duplication followed by accelerated evolut ion from an ancestral gene. (C) 2000 Federation of European Biochemical Soc ieties.