Publication: A key enzyme of the NAD<sup>+</sup>salvage pathway in Thermus thermophilus: Characterization of nicotinamidase and the impact of its gene deletion at high temperatures
Issued Date
2017-09-01
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ISSN
10985530
00219193
00219193
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2-s2.0-85027502404
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Bacteriology. Vol.199, No.17 (2017)
Suggested Citation
Hironori Taniguchi, Sathidaphorn Sungwallek, Phatcharin Chotchuang, Kenji Okano, Kohsuke Honda A key enzyme of the NAD<sup>+</sup>salvage pathway in Thermus thermophilus: Characterization of nicotinamidase and the impact of its gene deletion at high temperatures. Journal of Bacteriology. Vol.199, No.17 (2017). Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/41740
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Title
A key enzyme of the NAD<sup>+</sup>salvage pathway in Thermus thermophilus: Characterization of nicotinamidase and the impact of its gene deletion at high temperatures
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Abstract
© 2017 American Society for Microbiology. All Rights Reserved. NAD (NAD+) is a cofactor related to many cellular processes. This cofactor is known to be unstable, especially at high temperatures, where it chemically decomposes to nicotinamide and ADP-ribose. Bacteria, yeast, and higher organisms possess the salvage pathway for reconstructing NAD+from these decomposition products; however, the importance of the salvage pathway for survival is not well elucidated, except for in pathogens lacking the NAD+de novo synthesis pathway. Herein, we report the importance of the NAD+salvage pathway in the thermophilic bacterium Thermus thermophilus HB8 at high temperatures. We identified the gene encoding nicotinamidase (TTHA0328), which catalyzes the first reaction of the NAD+salvage pathway. This recombinant enzyme has a high catalytic activity against nicotinamide (Kmof 17 μM, kcatof 50 s-1, kcat/Kmof 3.0 × 103 s-1· mM-1). Deletion of this gene abolished nicotinamide deamination activity in crude extracts of T. thermophilus and disrupted the NAD+salvage pathway in T. thermophilus. Disruption of the salvage pathway led to the severe growth retardation at a higher temperature (80°C), owing to the drastic decrease in the intracellular concentrations of NAD+and NADH.