Enhanced aldehyde dehydrogenase activity by regenerating NAD+ in Klebsiella pneumoniae and implications for the glycerol dissimilation pathways.

TitleEnhanced aldehyde dehydrogenase activity by regenerating NAD+ in Klebsiella pneumoniae and implications for the glycerol dissimilation pathways.
Publication TypeJournal Article
Year of Publication2013
AuthorsLi Y, Su M, Ge X, Tian P
JournalBiotechnology letters
Volume35
Issue10
Pagination1609-15
Date Published2013 Oct
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.

DOI10.1182/blood-2013-08-517474
Alternate JournalBiotechnol. Lett.