Department of Molecular, Cellular and Developmental Biology and the Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, CO, USA.
FEBS J. 2020 Apr;287(7):1262-1283. doi: 10.1111/febs.15299.
Thousands of new metabolic and regulatory enzymes have evolved by gene duplication and divergence since the dawn of life. New enzyme activities often originate from promiscuous secondary activities that have become important for fitness due to a change in the environment or a mutation. Mutations that make a promiscuous activity physiologically relevant can occur in the gene encoding the promiscuous enzyme itself, but can also occur elsewhere, resulting in increased expression of the enzyme or decreased competition between the native and novel substrates for the active site. If a newly useful activity is inefficient, gene duplication/amplification will set the stage for divergence of a new enzyme. Even a few mutations can increase the efficiency of a new activity by orders of magnitude. As efficiency increases, amplified gene arrays will shrink to provide two alleles, one encoding the original enzyme and one encoding the new enzyme. Ultimately, genomic rearrangements eliminate co-amplified genes and move newly evolved paralogs to a distant region of the genome.
数千种新的代谢和调节酶自生命起源以来通过基因复制和分化而进化。新的酶活性通常源自于原本的次要活性，由于环境的变化或突变，这些次要活性变得对适应性很重要。使原本的次要活性在生理上变得相关的突变可以发生在编码该酶的基因本身，但也可能发生在其他地方，从而导致酶的表达增加，或者原生和新底物对活性位点的竞争减少。如果新的有用活性效率低下，那么基因复制/扩增将为新酶的分化奠定基础。即使只有少数突变也可以使新活性的效率提高几个数量级。随着效率的提高，扩增的基因序列会缩小，从而产生两个等位基因，一个编码原始酶，另一个编码新酶。最终，基因组重排会消除共扩增的基因，并将新进化的基因转移到基因组的遥远区域。
