Chijiwa Takahito, Ikeda Naoki, Masuda Haruna, Hara Hiroaki, Oda-Ueda Naoko, Hattori Shosaku, Ohno Motonori
Department of Applied Life Science, Faculty of Bioscience and Biotechnology, Sojo University, Ikeda, Kumamoto, Japan.
Biosci Biotechnol Biochem. 2012;76(3):551-8. doi: 10.1271/bbb.110848.
A novel phospholipase A(2) (PLA(2)) gene, named PfPLA 6, was found in a 6,328-bp NIS-1(5')-a segment in the Protobothrops flavoviridis (Habu, Crotalinae) genome. A comparison of the aligned nucleotide sequences of Viperidae (Viperinae and Crotalinae) venom PLA(2) genes, including PfPLA 6, revealed the deletion of a 12-bp segment called S1EX 1 and a 55-bp segment called S2EX 1 in exon 1 and the interposition of a 219-bp segment called SINT 2 (SINE) in intron 2. A classification of Viperidae PLA(2) genes based on these structural modes indicated that the A-type genes (without SINE), including PfPLA 6, are evolutionarily ancestral to the B-type (Viperinae) and C-type (Crotalinae) PLA(2) genes (both with SINE). Since PfPLA 6 is a pseudogene, an active prototype of PfPLA 6 can be assumed to be the ancestral PLA(2) gene. Putative evolutionary processes from this A-type prototype PLA(2) gene to descendent PLA(2) genes are discussed.
在原矛头蝮（竹叶青蛇，蝰蛇科）基因组中一段6328 bp的NIS-1(5')-a片段中发现了一个名为PfPLA 6的新型磷脂酶A(2)（PLA(2)）基因。对包括PfPLA 6在内的蝰蛇科（蝰亚科和蝮亚科）毒液PLA(2)基因的比对核苷酸序列进行比较，结果显示外显子1中一个名为S1EX 1的12 bp片段和一个名为S2EX 1的55 bp片段缺失，内含子2中插入了一个名为SINT 2（短散在重复元件）的219 bp片段。基于这些结构模式对蝰蛇科PLA(2)基因进行分类表明，包括PfPLA 6在内的A型基因（无短散在重复元件）在进化上是B型（蝰亚科）和C型（蝮亚科）PLA(2)基因（均有短散在重复元件）的祖先。由于PfPLA 6是一个假基因，可以假定PfPLA 6的一个活性原型是祖先PLA(2)基因。本文讨论了从这种A型原型PLA(2)基因到后代PLA(2)基因的假定进化过程。
