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

Abstract

The structure and organization of five genes responsible for the synthesis of six isoforms of short-chain alpha-neurotoxins in Pseudonaja textilis venom are reported in this paper. This also forms the first report which describes 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 promoter. The promoter activity was confirmed by both CAT assay and Real-Time PCR. A transcription initiation site, two putative TATA boxes, one CCAAT box and 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 analysis showed that these five genes from P. textilis constituted a distinct group which has evolved by gene duplication followed by accelerated evolution from an ancestral gene.