Interisland mutation of a novel phospholipase A2 from Trimeresurus flavoviridis venom and evolution of crotalinae group II phospholipases A2
Interisland mutation of a novel phospholipase A2 from Trimeresurus flavoviridis venom and evolution of crotalinae group II phospholipases A2
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DOI：
10.1007/s00239-003-2508-4
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发表时间：
2003-11-01
影响因子：
3.9
通讯作者：
Ohno, M
中科院分区：
文献类型：
--
作者：
Chijiwa, T;Hamai, S;Ohno, M
黄绿Trimeresurus （Crotalinae）蛇栖息在日本西南部的岛屿：奄美大岛、德野岛和冲绳。通过亲和层析和常规层析，分离出一种新的磷脂酶a (2) （PLA(2)）。该蛋白与一种神经毒性聚乳酸（PLA）(2)高度同源（91%），具有较弱的神经毒性。这种蛋白被命名为PLA-N。其对小鼠的LD50为1.34马克/克，与三苦毒相当。从Amami-Oshima和Tokunoshima T. flavviridis毒腺cDNA文库中分离到编码PLA-N的cDNA。用PLA-N cDNA对冲绳岛黄病毒t毒腺cDNA文库进行筛选，分离出一个氨基酸取代的PLA-N同源物，命名为PLA-N(O)，表明冲绳岛发生了岛间突变，在天美大岛和德野岛分离之前，冲绳岛从原来的岛屿分离出来。根据氨基酸序列构建了Crotalinae毒液第11群PLA(2) s的系统发育树，发现PLA- n和PLA- n (O)等神经毒性PLA-(2) s与PLA(2)型、碱性[Asp(49)]PLA(2)型和[Lys(49)]PLA(2)型等PLA-(2) s形成一个独立的簇。PLA- n cDNA的核苷酸序列与其他黄黄毒PLA(2)’S编码的cDNA序列的比较表明，它们的进化速度加快。然而，当对编码Crotalinae毒液神经毒性PLA(2)’S的cdna进行比较时，它们的进化速率似乎降低到加速进化和中性进化之间的水平。可能是神经毒性PLA(2)的祖先基因以一种加速的方式进化，直到它们获得神经毒性功能，从那时起，它们进化的突变频率较低，可能是为了功能保护。
Trimeresurus flavoviridis (Crotalinae) snakes inhabit the southwestern islands of Japan: Amami-Oshima, Tokunoshima, and Okinawa. Affinity and conventional chromatographies of Amami-Oshima T. flavoviridis venom led to isolation of a novel phospholipase A(2) (PLA(2)). This protein was highly homologous (91%) in sequence to trimucrotoxin, a neurotoxic PLA(2), which had been isolated from T. mucrosquamatus (Taiwan) venom, and exhibited weak neurotoxicity. This protein was named PLA-N. Its LD50 for mice was 1.34 mug/g, which is comparable to that of trimucrotoxim. The cDNA encoding PLA-N was isolated from both the Amami-Oshima and the Tokunoshima T. flavoviridis venom-gland cDNA libraries. Screening of the Okinawa T. flavoviridis venom-gland cDNA library with PLA-N cDNA led to isolation of the cDNA encoding one amino acid-substituted PLA-N homologue, named PLA-N(O), suggesting that interisland mutation occurred and that Okinawa island was separated from a former island prior to dissociation of Amami-Oshima and Tokunoshima islands. Construction of a phylogenetic tree of Crotalinae venom group 11 PLA(2)'s based on the amino acid sequences revealed that neurotoxic PLA-(2)'s including PLA-N and PLA-N(O) form an independent cluster which is distant from other PLA-(2), groups such as PLA(2) type, basic [Asp(49)]PLA(2) type, and [Lys(49)]PLA(2) type. Comparison of the nucleotide sequence of PLA-N cDNA with those of the cDNAs encoding other T. flavoviridis venom PLA(2)'S showed that they have evolved in an accelerated manner. However, when comparison was made within the cDNAs encoding Crotalinae venom neurotoxic PLA(2)'S, their evolutionary rates appear to be reduced to a level between accelerated evolution and neutral evolution. It is likely that ancestral genes of neurotoxic PLA(2)'s evolved in an accelerated manner until they had acquired neurotoxic function and since then they have evolved with less frequent mutation, possibly for functional conservation.