title: Metabolic engineering of 3-hydroxypropionic acid biosynthesis in Escherichia coli.
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.
authors.affiliation: Biomaterials Lab, Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, Korea.
authors.forename: Hun Su
authors.initials: HS
authors.lastname: Chu
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Chan Mu
authors.initials: CM
authors.lastname: Lee
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Lee
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Jung
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Ahn
authors.forename: Seung Hoon
authors.initials: SH
authors.lastname: Song
authors.forename: In Suk
authors.initials: IS
authors.lastname: Choi
authors.forename: Kwang Myung
authors.initials: KM
authors.lastname: Cho
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D019344:Lactic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D008958:Models, Molecular
chemical_list: D001426:Bacterial Proteins; D019344:Lactic Acid; C031601:hydracrylic acid; D000444:Aldehyde Dehydrogenase; D005990:Glycerol
keywords: 3-hydroxypropionic acid (3-HP); GabD4; aldehyde dehydrogenase; glycerol