Evolution of enzymes in metabolism: A network perspective
Evolution of enzymes in metabolism: A network perspective
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DOI：
10.1016/s0022-2836(02)00546-6
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发表时间：
2002-07-19
影响因子：
5.6
通讯作者：
Sternberg, MJE
中科院分区：
文献类型：
--
作者：
Alves, R;Chaleil, RAG;Sternberg, MJE
已经提出了几个模型来解释代谢途径中酶的起源和进化。最初，逆向进化模型提出，当途径末端的酶在原始汤中耗尽其底物时，有压力在途径中创建较早的酶，以较晚的酶为初始模板，以补充耗尽的代谢物池。后来，招募模型提出，只要这些酶在化学或底物特异性上相似，就可以使用来自其他途径的初始模板。这两种模型在最近的酶进化研究中占主导地位。这些研究要么受到研究规模小的限制，要么受到途径定义施加的人为限制。在这里，一种网络方法被用来研究酶的进化在完全测序的基因组，从而消除了这两个限制。我们发现，在反应网络中，同源酶对从距离小于三步的酶进化而来的可能性大约是非同源酶对的两倍。这些结果，以及进化相关酶催化的化学反应类型的守恒，表明类似化学的功能块在代谢网络中已经进化。对这些观察结果的一种可能的解释是，这种局部进化现象可能比代谢网络中远离它们的其他酶的进化更少地引起新陈代谢的全局生理破坏。(C) 2002 Elsevier Science Ltd.版权所有。
Several models have been proposed to explain the origin and evolution of enzymes in metabolic pathways. Initially, the retro-evolution model proposed that, as enzymes at the end of pathways depleted their substrates in the primordial soup, there was a pressure for earlier enzymes in pathways to be created, using the later ones as initial template, in order to replenish the pools of depleted metabolites. Later, the recruitment model proposed that initial templates from other pathways could be used as long as those enzymes were similar in chemistry or substrate specificity. These two models have dominated recent studies of enzyme evolution. These studies are constrained by either the small scale of the study or the artificial restrictions imposed by pathway definitions. Here, a network approach is used to study enzyme evolution in fully sequenced genomes, thus removing both constraints. We find that homologous pairs of enzymes are roughly twice as likely to have evolved from enzymes that are less than three steps away from each other in the reaction network than pairs of non-homologous enzymes. These results, together with the conservation of the type of chemical reaction catalyzed by evolutionarily related enzymes, suggest that functional blocks of similar chemistry have evolved within metabolic networks. One possible explanation for these observations is that this local evolution phenomenon is likely to cause less global physiological disruptions in metabolism than evolution of enzymes from other enzymes that are distant from them in the metabolic network. (C) 2002 Elsevier Science Ltd. All rights reserved.