Michael Anthony J
Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park, Dallas, TX 75390, U.S.A.
Biochem J. 2017 Jun 27;474(14):2277-2299. doi: 10.1042/BCJ20160823.
Since the emergence of the last common ancestor from which all extant life evolved, the metabolite repertoire of cells has increased and diversified. Not only has the metabolite cosmos expanded, but the ways in which the same metabolites are made have diversified. Enzymes catalyzing the same reaction have evolved independently from different protein folds; the same protein fold can produce enzymes recognizing different substrates, and enzymes performing different chemistries. Genes encoding useful enzymes can be transferred between organisms and even between the major domains of life. Organisms that live in metabolite-rich environments sometimes lose the pathways that produce those same metabolites. Fusion of different protein domains results in enzymes with novel properties. This review will consider the major evolutionary mechanisms that generate biosynthetic diversity: gene duplication (and gene loss), horizontal and endosymbiotic gene transfer, and gene fusion. It will also discuss mechanisms that lead to convergence as well as divergence. To illustrate these mechanisms, one of the original metabolisms present in the last universal common ancestor will be employed: polyamine metabolism, which is essential for the growth and cell proliferation of archaea and eukaryotes, and many bacteria.
自从所有现存生命演化而来的最后一个共同祖先出现以来，细胞的代谢物种类已经增加并多样化。不仅代谢物宇宙得到了扩展，而且产生相同代谢物的方式也变得多样化。催化相同反应的酶已经从不同的蛋白质折叠中独立进化而来；相同的蛋白质折叠可以产生识别不同底物的酶，以及执行不同化学反应的酶。编码有用酶的基因可以在生物体之间甚至在生命的主要领域之间转移。生活在富含代谢物环境中的生物体有时会失去产生那些相同代谢物的途径。不同蛋白质结构域的融合产生了具有新特性的酶。本综述将探讨产生生物合成多样性的主要进化机制：基因复制（和基因丢失）、水平和内共生基因转移以及基因融合。它还将讨论导致趋同和分化的机制。为了说明这些机制，将采用最后一个普遍共同祖先中存在的一种原始代谢：多胺代谢，它对古细菌、真核生物和许多细菌的生长和细胞增殖至关重要。
