Directing enzyme devolution for biosynthesis of alkanols and 1, n-alkanediols from natural polyhydroxy compounds
Directing enzyme devolution for biosynthesis of alkanols and 1, n-alkanediols from natural polyhydroxy compounds
复制标题
指导酶转移从天然多羟基化合物生物合成链烷醇和 1, n-链烷二醇
DOI：
10.1016/j.ymben.2017.09.005
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发表时间：
2017-11-01
影响因子：
8.4
通讯作者：
Xu, Ping
中科院分区：
文献类型：
--
作者：
Dai, Lu;Tao, Fei;Xu, Ping
原始酶被认为具有广泛的特异性。通过分歧和进化，酶已被改进以表现出对一种反应或底物的特异性，因此通常被认为是“专家”。然而，一些酶是催化一系列底物和反应的“多面手”。这种特性被定义为酶的混杂性，对于新功能的进化非常重要。本文利用两种酶（即甘油脱水酶和二醇脱水酶）的混杂来催化长链多元醇，包括1,2-丁二醇、1,2,4-丁三醇、赤藓醇、1,2-戊二醇、1,2,5-戊三醇和1,2,6-己三醇。通过体外酶测定研究了催化这六种长链多元醇所需的比活性，并通过蛋白质工程提高了催化效率。随后将混杂的功能应用于体内，以建立来自木质纤维素衍生化合物（包括木糖和赤藓糖醇）的1,4-丁二醇途径。此外，还构建了由1,2-戊二醇生产1-戊醇的途径。结果表明，利用酶的混杂性有望探索新的催化剂，这将扩大合成生物学可用的遗传元件库，并可能为设计和工程有价值的化学品的新途径提供一个起点。
Primordial enzymes are proposed to possess broad specificities. Through divergence and evolution, enzymes have been refined to exhibit specificity towards one reaction or substrate, and are thus commonly assumed as "specialists". However, some enzymes are "generalists" that catalyze a range of substrates and reactions. This property has been defined as enzyme promiscuity and is of great importance for the evolution of new functions. The promiscuities of two enzymes, namely glycerol dehydratase and diol dehydratase, were herein exploited for catalyzing long-chain polyols, including 1,2-butanediol, 1,2,4-butanetriol, erythritol, 1,2-pentanediol, 1,2,5-pentanetriol, and 1,2,6-hexanetriol. The specific activities required for catalyzing these six long-chain polyols were studied via in vitro enzyme assays, and the catalytic efficiencies were increased through protein engineering. The promiscuous functions were subsequently applied in vivo to establish 1,4-butanediol pathways from lignocellulose derived compounds, including xylose and erythritol. In addition, a pathway for 1-pentanol production from 1,2-pentanediol was also constructed. The results suggest that exploiting enzyme promiscuity is promising for exploring new catalysts, which would expand the repertoire of genetic elements available to synthetic biology and may provide a starting point for designing and engineering novel pathways for valuable chemicals.