Metabolic engineering of 3-hydroxypropionic acid biosynthesis in Escherichia coli

• Published in: Biotechnology and bioengineering Vol. 112; no. 2; pp. 356 - 364
• Main Authors: Chu, Hun Su, Kim, Young Soo, Lee, Chan Mu, Lee, Ju Hee, Jung, Won Seok, Ahn, Jin-Ho, Song, Seung Hoon, Choi, In Suk, Cho, Kwang Myung
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01-02-2015; Wiley Subscription Services, Inc
• Subjects: 3-hydroxypropionic acid (3-HP); aldehyde dehydrogenase; Aldehyde Dehydrogenase - chemistry; Aldehyde Dehydrogenase - genetics; Aldehyde Dehydrogenase - metabolism; Aldehydes; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cupriavidus necator - enzymology; Cupriavidus necator - genetics; E coli; Enzyme activity; Enzymes; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; GabD4; glycerol; Glycerol - metabolism; Homology; Lactic Acid - analogs & derivatives; Lactic Acid - analysis; Lactic Acid - metabolism; Metabolic Engineering - methods; Microorganisms; Models, Molecular; Mutagenesis; Mutation; Platforms; Productivity; Toxicity; aldehyde dehydrogenase; 3-hydroxypropionic acid (3-HP); GabD4; glycerol
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.25444

ABSTRACT
3‐Hydroxypropionic acid (3‐HP) can be produced in microorganisms as a versatile platform chemical. However, owing to the toxicity of the intermediate product 3‐hydroxypropionaldehyde (3‐HPA), the minimization of 3‐HPA accumulation is critical for enhancing the productivity of 3‐HP. In this study, we identified a novel aldehyde dehydrogenase, GabD4 from Cupriavidus necator, and found that it possessed the highest enzyme activity toward 3‐HPA reported to date. To augment the activity of GabD4, several variants were obtained by site‐directed and saturation mutagenesis based on homology modeling. Escherichia coli transformed with the mutant GabD4_E209Q/E269Q showed the highest enzyme activity, which was 1.4‐fold higher than that of wild type GabD4, and produced up to 71.9 g L−1 of 3‐HP with a productivity of 1.8 g L−1 h−1. To the best of our knowledge, these are the highest 3‐HP titer and productivity values among those reported in the literature. Additionally, our study demonstrates that GabD4 can be a key enzyme for the development of industrial 3‐HP‐producing microbial strains, and provides further insight into the mechanism of aldehyde dehydrogenase activity. Biotechnol. Bioeng. 2015;112: 356–364. © 2014 Wiley Periodicals, Inc.
3‐Hydroxypropionic acid can be produced in microorganisms as a versatile platform chemical. In this study, the authors identified a novel aldehyde dehydrogenase, GabD4 from Cupriavidus necator and engineered gabD4 by site‐directed mutagenesis based on homology modeling to improve the specific activity. Utilization of the engineered GabD4 resulted in a 41.5% increase in 3‐HP production, yielding final titers of 71.9 g/L, which showed the feasibility of the industrial production of 3‐HP from glycerol.