TY - JOUR

T1 - Exploring Bacterial Carboxylate Reductases for the Reduction of Bifunctional Carboxylic Acids

AU - Khusnutdinova, Anna N

AU - Flick, Robert

AU - Popovic, Ana

AU - Brown, Greg

AU - Tchigvintsev, Anatoli

AU - Nocek, Boguslaw

AU - Correia, Kevin

AU - Joo, Jeong C

AU - Mahadevan, Radhakrishnan

AU - Yakunin, Alexander F

N1 - © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PY - 2017/11/1

Y1 - 2017/11/1

N2 - Carboxylic acid reductases (CARs) selectively reduce carboxylic acids to aldehydes using ATP and NADPH as cofactors under mild conditions. Although CARs attracts significant interest, only a few enzymes have been characterized to date, whereas the vast majority of CARs have yet to be examined. Herein the authors report that 12 bacterial CARs reduces a broad range of bifunctional carboxylic acids containing oxo-, hydroxy-, amino-, or second carboxyl groups with several enzymes showing activity toward 4-hydroxybutanoic (4-HB) and adipic acids. These CARs exhibits significant reductase activity against substrates whose second functional group is separated from the carboxylate by at least three carbons with both carboxylate groups being reduced in dicarboxylic acids. Purified CARs supplemented with cofactor regenerating systems (for ATP and NADPH), an inorganic pyrophosphatase, and an aldo-keto reductase catalyzes a high conversion (50-76%) of 4-HB to 1,4-butanediol (1,4-BDO) and adipic acid to 1,6-hexanediol (1,6-HDO). Likewise, Escherichia coli strains expressing eight different CARs efficiently reduces 4-HB to 1,4-BDO with 50-95% conversion, whereas adipic acid is reduced to a mixture of 6-hydroxyhexanoic acid (6-HHA) and 1,6-HDO. Thus, our results illustrate the broad biochemical diversity of bacterial CARs and their compatibility with other enzymes for applications in biocatalysis.

AB - Carboxylic acid reductases (CARs) selectively reduce carboxylic acids to aldehydes using ATP and NADPH as cofactors under mild conditions. Although CARs attracts significant interest, only a few enzymes have been characterized to date, whereas the vast majority of CARs have yet to be examined. Herein the authors report that 12 bacterial CARs reduces a broad range of bifunctional carboxylic acids containing oxo-, hydroxy-, amino-, or second carboxyl groups with several enzymes showing activity toward 4-hydroxybutanoic (4-HB) and adipic acids. These CARs exhibits significant reductase activity against substrates whose second functional group is separated from the carboxylate by at least three carbons with both carboxylate groups being reduced in dicarboxylic acids. Purified CARs supplemented with cofactor regenerating systems (for ATP and NADPH), an inorganic pyrophosphatase, and an aldo-keto reductase catalyzes a high conversion (50-76%) of 4-HB to 1,4-butanediol (1,4-BDO) and adipic acid to 1,6-hexanediol (1,6-HDO). Likewise, Escherichia coli strains expressing eight different CARs efficiently reduces 4-HB to 1,4-BDO with 50-95% conversion, whereas adipic acid is reduced to a mixture of 6-hydroxyhexanoic acid (6-HHA) and 1,6-HDO. Thus, our results illustrate the broad biochemical diversity of bacterial CARs and their compatibility with other enzymes for applications in biocatalysis.

KW - Adenosine Triphosphate/metabolism

KW - Adipates

KW - Bacterial Proteins/genetics

KW - Carboxylic Acids/metabolism

KW - Escherichia coli/enzymology

KW - Hydroxybutyrates

KW - Metabolic Engineering/methods

KW - NADP/metabolism

KW - Oxidoreductases/genetics

U2 - 10.1002/biot.201600751

DO - 10.1002/biot.201600751

M3 - Article

C2 - 28762640

VL - 12

JO - Biotechnology Journal

JF - Biotechnology Journal

SN - 1860-6768

IS - 11

M1 - 1600751

ER -