CYP6B1 and CYP6B3 of the black swallowtail (Papilio polyxenes): adaptive evolution through subfunctionalization.
CYP6B1 and CYP6B3 of the black swallowtail (Papilio polyxenes): adaptive evolution through subfunctionalization.
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DOI：
10.1093/molbev/msl118
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发表时间：
2006-12
影响因子：
10.7
通讯作者：
Z. Wen;S. Rupasinghe;Guodong Niu;M. Berenbaum;M. Schuler
中科院分区：
文献类型：
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作者：
Z. Wen;S. Rupasinghe;Guodong Niu;M. Berenbaum;M. Schuler
基因复制为蛋白质的功能分化提供了必要的物质，从而使生物体能够适应不断变化的环境。在重复事件发生后，冗余的类似物可能通过非功能化、新功能化或亚功能化的过程经历不同的进化路径。通过计算分析核苷酸取代模式，在分子水平上对适应性进化的研究取得了迅速进展，但由于缺乏与编码酶功能改变有关的信息，这些研究受到限制。在这方面，负责这种昆虫适应含有呋喃香豆素的寄主植物的多色凤蝶细胞色素P450单加氧酶（P450）的进化为阐明重复基因的进化命运提供了一个很好的模型。从序列和功能分析结合分子模型的证据表明，同源的CYP6B1和CYP6B3基因可能是在它们产生的复制事件后通过亚功能化进化而来的。这两种酶在编码区和底物识别位点的dN/dS比都很低，证明了它们是经过独立纯化选择的。这两种酶都保持了它们代谢线状和角状呋喃香豆素的能力，尽管效率不同。CYP6B3和CYP6B1蛋白的分子模型的比较突出了它们结合模式的差异，这解释了它们对线性和角呋喃香豆素的不同活性。P. polyxenes维持了这两个具有不同活性和表达模式的呋喃香豆素代谢位点，这为该物种提供了获得具有新功能的p450的潜力，同时保持了对其在当前寄主植物范围内的独家取食最关键的p450。
Gene duplication provides essential material for functional divergence of proteins and hence allows organisms to adapt to changing environments. Following duplication events, redundant paralogs may undergo different evolutionary paths via processes known as nonfunctionalization, neofunctionalization, or subfunctionalization. Studies of adaptive evolution at the molecular level have progressed rapidly by computationally analyzing nucleotide substitution patterns but such studies are limited by the absence of information relating to alterations of function of the encoded enzymes. In this respect, evolution of the Papilio polyxenes cytochrome P450 monooxygenases (P450s) responsible for the adaptation of this insect to furanocoumarin-containing host plants provides an excellent model for elucidating the evolutionary fate of duplicated genes. Evidence from sequence and functional analysis in combination with molecular modeling indicates that the paralogous CYP6B1 and CYP6B3 genes in P. polyxenes have probably evolved via subfunctionalization after the duplication event by which they arose. Both enzymes have been under independent purifying selection as evidenced by the low dN/dS ratio in both the coding region and substrate recognition sites. Both enzymes have maintained their ability to metabolize linear and angular furanocoumarins albeit at different efficiencies. Comparisons of molecular models developed for the CYP6B3 and CYP6B1 proteins highlight differences in their binding modes that account for their different activities toward linear and angular furanocoumarins. That P. polyxenes maintains these 2 furanocoumarin-metabolizing loci with somewhat different activities and expression patterns provides this species with the potential to acquire P450s with novel functions while maintaining those most critical to its exclusive feeding on its current range of host plants.