NAD+ metabolite levels as a function of vitamins and calorie restriction: evidence for different mechanisms of longevity
1 Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
2 Michigan Metabolomics and Obesity Center, University of Michigan, Ann Arbor, MI 48109, USA
3 Biochemistry Graduate Program, Dartmouth Medical School, Lebanon, NH 03756, USA
4 Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
5 Department of Chemistry, University of Michigan, 930 N University Ave, Ann Arbor, MI 48109, USA
6 Department of Biochemistry, Carver College of Medicine, University of Iowa, 51 Newton Rd, 4-403 BSB, Iowa City, IA 52242, USA
BMC Chemical Biology 2010, 10:2 doi:10.1186/1472-6769-10-2Published: 22 February 2010
NAD+ is a coenzyme for hydride transfer enzymes and a substrate for sirtuins and other NAD+-dependent ADPribose transfer enzymes. In wild-type Saccharomyces cerevisiae, calorie restriction accomplished by glucose limitation extends replicative lifespan in a manner that depends on Sir2 and the NAD+ salvage enzymes, nicotinic acid phosphoribosyl transferase and nicotinamidase. Though alterations in the NAD+ to nicotinamide ratio and the NAD+ to NADH ratio are anticipated by models to account for the effects of calorie restriction, the nature of a putative change in NAD+ metabolism requires analytical definition and quantification of the key metabolites.
Hydrophilic interaction chromatography followed by tandem electrospray mass spectrometry were used to identify the 12 compounds that constitute the core NAD+ metabolome and 6 related nucleosides and nucleotides. Whereas yeast extract and nicotinic acid increase net NAD+ synthesis in a manner that can account for extended lifespan, glucose restriction does not alter NAD+ or nicotinamide levels in ways that would increase Sir2 activity.
The results constrain the possible mechanisms by which calorie restriction may regulate Sir2 and suggest that provision of vitamins and calorie restriction extend lifespan by different mechanisms.