异丁醇
代谢工程
生物化学
辅因子
醇脱氢酶
NAD+激酶
烟酰胺腺嘌呤二核苷酸
化学
脱氢酶
酶
生物
酒
作者
Sabine Bastian,Xiang Liu,Joseph T. Meyerowitz,Christopher D. Snow,Mike M.Y. Chen,Frances H. Arnold
标识
DOI:10.1016/j.ymben.2011.02.004
摘要
2-methylpropan-1-ol (isobutanol) is a leading candidate biofuel for the replacement or supplementation of current fossil fuels. Recent work has demonstrated glucose to isobutanol conversion through a modified amino acid pathway in a recombinant organism. Although anaerobic conditions are required for an economically competitive process, only aerobic isobutanol production has been feasible due to an imbalance in cofactor utilization. Two of the pathway enzymes, ketol-acid reductoisomerase and alcohol dehydrogenase, require nicotinamide dinucleotide phosphate (NADPH); glycolysis, however, produces only nicotinamide dinucleotide (NADH). Here, we compare two solutions to this imbalance problem: (1) over-expression of pyridine nucleotide transhydrogenase PntAB and (2) construction of an NADH-dependent pathway, using engineered enzymes. We demonstrate that an NADH-dependent pathway enables anaerobic isobutanol production at 100% theoretical yield and at higher titer and productivity than both the NADPH-dependent pathway and transhydrogenase over-expressing strain. Our results show how engineering cofactor dependence can overcome a critical obstacle to next-generation biofuel commercialization.
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