TY - JOUR

T1 - One-pot biocatalytic transformation of adipic acid to 6-aminocaproic acid and 1,6-hexamethylenediamine using carboxylic acid reductases and transaminases

AU - Fedorchuk, Tatiana P.

AU - Khusnutdinova, Anna N.

AU - Evdokimova, Elena

AU - Flick, Robert

AU - Di Leo, Rosa

AU - Stogios, Peter J.

AU - Savchenko, Alexei

AU - Yakunin, Alexander

PY - 2020/1/15

Y1 - 2020/1/15

N2 - Production of platform chemicals from renewable feedstocks is becoming increasingly important due to concerns on environmental contamination, climate change, and depletion of fossil fuels. Adipic acid (AA), 6-aminocaproic acid (6-ACA) and 1,6-hexamethylenediamine (HMD) are key precursors for nylon synthesis, which are currently produced primarily from petroleum-based feedstocks. In recent years, the biosynthesis of adipic acid from renewable feedstocks has been demonstrated using both bacterial and yeast cells. Here we report the biocatalytic conversion/transformation of AA to 6-ACA and HMD by carboxylic acid reductases (CARs) and transaminases (TAs), which involves two rounds (cascades) of reduction/amination reactions (AA → 6-ACA → HMD). Using purified wild type CARs and TAs supplemented with cofactor regenerating systems for ATP, NADPH, and amine donor, we established a one-pot enzyme cascade catalyzing up to 95% conversion of AA to 6-ACA. To increase the cascade activity for the transformation of 6-ACA to HMD, we determined the crystal structure of the CAR substrate-binding domain in complex with AMP and succinate and engineered three mutant CARs with enhanced activity against 6-ACA. In combination with TAs, the CAR L342E protein showed 50-75% conversion of 6-ACA to HMD. For the transformation of AA to HMD (via 6-ACA), the wild type CAR was combined with the L342E variant and two different TAs resulting in up to 30% conversion to HMD and 70% to 6-ACA. Our results highlight the suitability of CARs and TAs for several rounds of reduction/amination reactions in one-pot cascade systems and their potential for the bio-based synthesis of terminal amines.

AB - Production of platform chemicals from renewable feedstocks is becoming increasingly important due to concerns on environmental contamination, climate change, and depletion of fossil fuels. Adipic acid (AA), 6-aminocaproic acid (6-ACA) and 1,6-hexamethylenediamine (HMD) are key precursors for nylon synthesis, which are currently produced primarily from petroleum-based feedstocks. In recent years, the biosynthesis of adipic acid from renewable feedstocks has been demonstrated using both bacterial and yeast cells. Here we report the biocatalytic conversion/transformation of AA to 6-ACA and HMD by carboxylic acid reductases (CARs) and transaminases (TAs), which involves two rounds (cascades) of reduction/amination reactions (AA → 6-ACA → HMD). Using purified wild type CARs and TAs supplemented with cofactor regenerating systems for ATP, NADPH, and amine donor, we established a one-pot enzyme cascade catalyzing up to 95% conversion of AA to 6-ACA. To increase the cascade activity for the transformation of 6-ACA to HMD, we determined the crystal structure of the CAR substrate-binding domain in complex with AMP and succinate and engineered three mutant CARs with enhanced activity against 6-ACA. In combination with TAs, the CAR L342E protein showed 50-75% conversion of 6-ACA to HMD. For the transformation of AA to HMD (via 6-ACA), the wild type CAR was combined with the L342E variant and two different TAs resulting in up to 30% conversion to HMD and 70% to 6-ACA. Our results highlight the suitability of CARs and TAs for several rounds of reduction/amination reactions in one-pot cascade systems and their potential for the bio-based synthesis of terminal amines.

KW - biocatalysis

KW - adipic acid

KW - 6-aminocaproic acid

KW - 1,6-hexamethylenediamine

KW - carboxylic acid reductase

KW - transaminase

UR - https://pubs.acs.org/doi/10.1021/jacs.9b11761?goto=supporting-info

U2 - 10.1021/jacs.9b11761

DO - 10.1021/jacs.9b11761

M3 - Article

VL - 142

SP - 1038

EP - 1048

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 2

ER -