Kordis D, Bdolah A, Gubensek F
Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
Biochem Biophys Res Commun. 1998 Oct 20;251(2):613-9. doi: 10.1006/bbrc.1998.9528.
The venom of Vipera palaestinae contains a two-component toxin, consisting of an acidic phospholipase A2 (PLA2) and a basic protein. Here we report the cloning and sequence analysis of the complete V. palaestinae PLA2 genes. Since in all Viperidae PLA2 multigene families the 5' and 3' flanking regions are highly conserved, we designed oligonucleotide primers that allow amplification of the whole PLA2 multigene family in a single step. The structural organization of both genes is the same as in the Vipera ammodytes PLA2 multigene family, there being five exons separated by four introns. Comparison of V. palaestinae PLA2 genes with other Viperidae PLA2 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 PLA2 genes, where it is present in all mature protein coding exons.
巴勒斯坦蝰蛇的毒液含有一种双组分毒素，由一种酸性磷脂酶A2（PLA2）和一种碱性蛋白组成。在此我们报告了完整的巴勒斯坦蝰蛇PLA2基因的克隆及序列分析。由于在所有蝰蛇科PLA2多基因家族中，5'和3'侧翼区域高度保守，我们设计了寡核苷酸引物，可在一步反应中扩增整个PLA2多基因家族。这两个基因的结构组织与极北蝰PLA2多基因家族相同，有五个外显子被四个内含子隔开。将巴勒斯坦蝰蛇PLA2基因与其他蝰蛇科PLA2基因进行比较表明，基因的结构组织以及所有内含子和侧翼区域的核苷酸序列高度保守，而第三个外显子明显显示出更多的氨基酸替换，这表明存在正达尔文选择。与其他蝰蛇科PLA2基因不同，正达尔文选择令人惊讶地仅限于第三个外显子，在其他蝰蛇科PLA2基因中，正达尔文选择存在于所有成熟蛋白编码外显子中。
