title: Enhanced aldehyde dehydrogenase activity by regenerating NAD+ in Klebsiella pneumoniae and implications for the glycerol dissimilation pathways.
abstract: In Klebsiella pneumoniae, 3-hydroxypropaldehyde is converted to 3-hydroxypropionic acid (3-HP) by aldehyde dehydrogenase (ALDH) with NAD(+) as a cofactor. Although ALDH overexpression stimulates the formation of 3-HP, it ceases to accumulate when NAD(+) is exhausted. Here we show that NAD(+) regeneration, together with ALDH overexpression, facilitates 3-HP production and benefits cell growth. Three distinct NAD(+)-regenerating enzymes: NADH oxidase and NADH dehydrogenase from K. pneumoniae, and glycerol-3-phosphate dehydrogenase (GPD1) from Saccharomyces cerevisiae, were individually expressed in K. pneumoniae. In vitro assay showed their higher activities than that of the control, indicating their capacities to regenerate NAD(+). When they were respectively co-expressed with ALD4, an ALDH from S. cerevisiae, the activities of ALD4 were significantly elevated compared with that expressing ALD4 alone, suggesting that the regenerated NAD(+) enhanced the activity of ALD4. More interestingly, the growth rates of all NAD(+)-regenerating strains were prolonged in comparison with the control, indicating that NAD(+) regeneration stimulated cell proliferation. This study not only reveals the reliance of ALD4 activity on NAD(+) availability but also provides a method for regulating the dha regulon.
authors.affiliation: College of Life Science and Technology, Beijing University of Chemical Technology, 100029, Beijing, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Mingyue
authors.initials: M
authors.lastname: Su
authors.forename: Xizhen
authors.initials: X
authors.lastname: Ge
authors.forename: Pingfang
authors.initials: P
authors.lastname: Tian
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000378:metabolism*; D015870:Gene Expression; D005985:Glyceraldehyde / Q000031:analogs & derivatives / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D005993:Glycerolphosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000378:metabolism*; D019344:Lactic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D060847:Metabolic Engineering; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D009243:NAD / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000235:genetics / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D011407:Propane / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D009243:NAD; C047158:3-hydroxypropionaldehyde; D019344:Lactic Acid; D005985:Glyceraldehyde; C031601:hydracrylic acid; D005993:Glycerolphosphate Dehydrogenase; D000444:Aldehyde Dehydrogenase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D009245:NADH Dehydrogenase; D005990:Glycerol; D011407:Propane