Domain Loss Facilitates Accelerated Evolution and Neofunctionalization of Duplicate Snake Venom Metalloproteinase Toxin Genes
Domain Loss Facilitates Accelerated Evolution and Neofunctionalization of Duplicate Snake Venom Metalloproteinase Toxin Genes
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DOI：
10.1093/molbev/msr091
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发表时间：
2011-09-01
影响因子：
10.7
通讯作者：
Wuester, Wolfgang
中科院分区：
文献类型：
--
作者：
Casewell, Nicholas R.;Wagstaff, Simon C.;Wuester, Wolfgang
基因复制是基因家族适应性进化和新功能化的重要机制。大的多基因家族往往表现出复杂的进化历史，作为一个结果，频繁的基因重复与积极的选择压力一致。基因结构域的改变，引起蛋白质分子支架的变化，也可能导致复杂的进化史，并已在功能多样的多基因毒素家族中观察到。在这里，我们调查的作用改变结构域结构上的进化和neofunctionalization的多基因家族的克里思使用蛇毒金属蛋白酶（SVMPs）作为一个模型系统。我们的研究结果表明，蝰蛇（蛇：蝰蛇科）SVMP的进化历史是反复打断域的损失，与单损失的半胱氨酸丰富的结构域，促进P-II类SVMP的形成，发生之前的收敛损失的去整合素结构域，形成多个P-I SVMP结构。值得注意的是，大多数推断发生结构域丢失的系统发育分支在表面暴露的氨基酸残基中表现出高度显著的正选择证据，导致P-II和P-I SVMP类的新功能化。这些结果为复杂基因家族的进化机制提供了有价值的见解，并详细说明了结构域结构的丧失如何催化新基因旁系同源物的加速进化。由相同的多基因家族编码的不同分子支架的随后产生促进基因新功能化，同时通过保留能够编码功能上不同的蛋白质的多个基因而呈现进化优势。
Gene duplication is a key mechanism for the adaptive evolution and neofunctionalization of gene families. Large multigene families often exhibit complex evolutionary histories as a result of frequent gene duplication acting in concordance with positive selection pressures. Alterations in the domain structure of genes, causing changes in the molecular scaffold of proteins, can also result in a complex evolutionary history and has been observed in functionally diverse multigene toxin families. Here, we investigate the role alterations in domain structure have on the tempo of evolution and neofunctionalization of multigene families using the snake venom metalloproteinases (SVMPs) as a model system. Our results reveal that the evolutionary history of viperid (Serpentes: Viperidae) SVMPs is repeatedly punctuated by domain loss, with the single loss of the cysteine-rich domain, facilitating the formation of P-II class SVMPs, occurring prior to the convergent loss of the disintegrin domain to form multiple P-I SVMP structures. Notably, the majority of phylogenetic branches where domain loss was inferred to have occurred exhibited highly significant evidence of positive selection in surface-exposed amino acid residues, resulting in the neofunctionalization of P-II and P-I SVMP classes. These results provide a valuable insight into the mechanisms by which complex gene families evolve and detail how the loss of domain structures can catalyze the accelerated evolution of novel gene paralogues. The ensuing generation of differing molecular scaffolds encoded by the same multigene family facilitates gene neofunctionalization while presenting an evolutionary advantage through the retention of multiple genes capable of encoding functionally distinct proteins.