Characterization of Carboxylic Acid Reductases for Biocatalytic Synthesis of Industrial Chemicals
Characterization of Carboxylic Acid Reductases for Biocatalytic Synthesis of Industrial Chemicals
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DOI：
10.1002/cbic.201800157
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发表时间：
2018-07-04
期刊：
影响因子：
3.2
通讯作者：
Niu, Wei
中科院分区：
文献类型：
--
作者：
Kramer, Levi;Hankore, Erome Daniel;Niu, Wei
羧酸还原酶 (CAR) 催化多种羧酸还原成醛，醛可作为许多工业化学品的常见生物合成前体。这项工作通过使用一组常见的细胞代谢物短链二羧酸和羟基酸，对来自不同微生物的五种羧酸还原酶（包括两种已知的和三种新的）进行了系统的生化表征。所有酶均表现出广泛的底物特异性。当二羧酸酯或末端羟基酸的碳链长度从C-2增加到C-6时，观察到更高的催化效率。此外，当比较相同碳链长度的底物时，羧酸还原酶更喜欢羟基酸而不是二羧酸盐作为底物。通过将 CAR 活性与大肠杆菌宿主中的醛还原酶的活性相结合，研究了 11 种羧酸底物到相应醇的全细胞生物转化。获得的酒精产品的收率范围为0.5%至71%。使用 CAR 作为关键途径酶，成功演示了 1,2-丙二醇对映体的从头立体特异性生物合成。大肠杆菌菌株从葡萄糖中积累了 7.0mm (R)-1,2-PDO（1.0% 产率）或 9.6mm (S)-1,2-PDO（1.4% 产率）。这项研究巩固了羧酸还原酶作为工业化学品可持续合成的有前途的酶。
Carboxylic acid reductases (CARs) catalyze the reduction of a broad range of carboxylic acids into aldehydes, which can serve as common biosynthetic precursors to many industrial chemicals. This work presents the systematic biochemical characterization of five carboxylic acid reductases from different microorganisms, including two known and three new ones, by using a panel of short-chain dicarboxylic acids and hydroxy acids, which are common cellular metabolites. All enzymes displayed broad substrate specificities. Higher catalytic efficiencies were observed when the carbon chain length, either of the dicarboxylates or of the terminal hydroxy acids, was increased from C-2 to C-6. In addition, when substrates of the same carbon chain length are compared, carboxylic acid reductases favor hydroxy acids over dicarboxylates as their substrates. Whole-cell bioconversions of eleven carboxylic acid substrates into the corresponding alcohols were investigated by coupling the CAR activity with that of an aldehyde reductase in Escherichia coli hosts. Alcohol products were obtained in yields ranging from 0.5% to 71%. The de novo stereospecific biosynthesis of propane-1,2-diol enantiomer was successfully demonstrated with use of CARs as the key pathway enzymes. E.coli strains accumulated 7.0mm (R)-1,2-PDO (1.0% yield) or 9.6mm (S)-1,2-PDO (1.4% yield) from glucose. This study consolidates carboxylic acid reductases as promising enzymes for sustainable synthesis of industrial chemicals.