Positive Darwinian Selection in Vipera palaestinae Phospholipase A Genes Is Unexpectedly Limited to the Third Exon
The venom of Vipera palaestinae contains a two-component toxin, consisting of an acidic phospholipase A sub(2) (PLA sub(2)) and a basic protein. Here we report the cloning and sequence analysis of the complete V. palaestinae PLA sub(2) genes. Since in all Viperidae PLA sub(2) multigene families the...
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Veröffentlicht in: | Biochemical and biophysical research communications 1998-10, Vol.251 (2), p.613-619 |
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Sprache: | eng |
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Zusammenfassung: | The venom of Vipera palaestinae contains a two-component toxin, consisting of an acidic phospholipase A sub(2) (PLA sub(2)) and a basic protein. Here we report the cloning and sequence analysis of the complete V. palaestinae PLA sub(2) genes. Since in all Viperidae PLA sub(2) multigene families the 5' and 3' flanking regions are highly conserved, we designed oligonucleotide primers that allow amplification of the whole PLA sub(2) multigene family in a single step. The structural organization of both genes is the same as in the Vipera ammodytes PLA sub(2) multigene family, there being five exons separated by four introns. Comparison of V. palaestinae PLA sub(2) genes with other Viperidae PLA sub(2) genes has shown that the structural organization of the genes and the nucleotide sequence of all introns and flanking regions are highly conserved, whereas the third exon clearly shows a higher number of amino acid replacements, an indication of positive Darwinian selection. The positive Darwinian selection is surprisingly limited to the third exon, in contrast to other Viperidae PLA sub(2) genes, where it is present in all mature protein coding exons. |
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ISSN: | 0006-291X |
DOI: | 10.1006/bbrc.1998.9528 |