Molecular cloning, characterization and evolution of the gene encoding a new group of short-chain α-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 α-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.