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Identification of UshA as a major enzyme for NAD degradation in Escherichia coli

Paper ID Volume ID Publish Year Pages File Format Full-Text
17208 42651 2014 5 PDF Available
Title
Identification of UshA as a major enzyme for NAD degradation in Escherichia coli
Abstract

•UshA harbors major NAD degradation activity.•UshA acts as NAD pyrophosphatase and 5′-nucleotidase.•Deletion of the ushA gene improves NAD stability and promotes cell growth.

Nicotinamide adenine dinucleotide (NAD) and its reduced form NADH are essential cofactors for many redox biocatalysts. Because these cofactors are consumed in stoichiometric amounts, whole-cell biocatalysts have been routinely employed in order to reduce the costs. To further improve the efficacy of redox biocatalysts, it is essential to maintain the stability of nicotinamide cofactors, for which it is attractive to block degradation pathways for NAD(H). While the biosynthesis of NAD(H) has been well studied, it is less understood how NAD(H) are degraded. Here we demonstrated that UshA was a major periplasmic enzyme for NAD degradation in Escherichia coli. Purified recombinant UshA showed high pyrophosphatase activity with the catalytic efficiencies for hydrolysis of NAD and NADH at 3.7 μM−1 s−1 and 1.4 μM−1 s−1, respectively. Deletion of the ushA gene from the chromosome led to faster cell growth and improved extracellular NAD stability by 3-fold under conditions similar to whole-cell biocatalysis. These results significantly enriched our understanding on NAD metabolism, and should facilitate many applications including designing more robust redox biocatalysts.

Keywords
Whole-cell biocatalysis; Nicotinamide adenine dinucleotide; NAD degradation; UshA; Pyrophosphatase; 5′-Nucleotidase
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Identification of UshA as a major enzyme for NAD degradation in Escherichia coli
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volumes 58–59, 10 May 2014, Pages 75–79
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us