Model-driven rebalancing of the intracellular redox state for optimization of a heterologous n-butanol pathway in Escherichia coli.
The intracellular redox state plays an important role in the cellular physiology that determines the efficiency of chemical and biofuel production by microbial cell factories. However, it is difficult to achieve optimal redox rebalancing of synthetic pathways owing to the sensitive responses of cellular physiology according as the intracellular redox state changes. Here, we demonstrate optimal rebalancing of the intracellular redox state by model-driven control of expression using n-butanol production in Escherichia coli as a model system. The synthetic n-butanol production pathway was constructed by implementing synthetic constitutive promoters and designing synthetic 5'-untranslated regions (5'-UTR) for each gene. Redox rebalancing was achieved by anaerobically activating the pyruvate dehydrogenase (PDH) complex and additionally tuning the expression level of NAD(+)-dependent formate dehydrogenase (fdh1 from Saccharomyces cerevisiae) through rational UTR engineering. Interestingly, efficient production of n-butanol required different amounts of reducing equivalents depending on whether the substrate was glucose or galactose. One intriguing implication of this work is that additional strain improvement can be achieved, even within given genetic components, through rebalancing intracellular redox state according to target products and substrates.
School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784, Korea.
Jae Hyung
JH
Lim
Sang Woo
SW
Seo
Se Yeon
SY
Kim
Gyoo Yeol
GY
Jung
D020001:1-Butanol / Q000378:metabolism*; D020121:5' Untranslated Regions / Q000235:genetics; D000693:Anaerobiosis / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005560:Formate Dehydrogenases / Q000096:biosynthesis / Q000235:genetics; D008954:Models, Biological; D010084:Oxidation-Reduction; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics
D020121:5' Untranslated Regions; D012329:RNA, Bacterial; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D020001:1-Butanol; C499416:FDH1 protein, S cerevisiae; D005560:Formate Dehydrogenases
Metabolic engineering; Metabolic imbalance; Redox rebalancing; Synthetic biology; n-butanol