NAD+ metabolite levels as a function of vitamins and calorie restriction: evidence for different mechanisms of longevity

Abstract

BackgroundNAD+ 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.ResultsHydrophilic 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.ConclusionsThe 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.

The 1.8 Å Cholix Toxin Crystal Structure in Complex with NAD+ and Evidence for a New Kinetic Model

“…Furthermore, a single physical site is consistent with dramatically different K D2 values among the cholix c mutants. Notably, physiological concentration of NAD ϩ has been reported as ϳ370 M in animal cells (41, 42) and 1-2 mM in yeast cells (43). Thus, the range of concentrations used in our experiments is physiologically relevant.…”

YCL047C/POF1 Is a Novel Nicotinamide Mononucleotide Adenylyltransferase (NMNAT) in Saccharomyces cerevisiae

“…Intracellular concentrations of many of the NAD ϩ intermediates are maintained at low levels (42), which is characteristic of signaling molecules. NR and NMN, similar to other NAD ϩ intermediates, may function as signaling molecules to regulate NAD ϩ homeostasis or other cellular processes.…”

Phosphate-responsive Signaling Pathway Is a Novel Component of NAD+ Metabolism in Saccharomyces cerevisiae

“…Chemically synthesized NmR, NaR (both were kindly provided by Dr. A. Sauve), NaMN (Sigma), NMN (Sigma), and NAD ϩ (Roche Applied Science) were used to establish standard curves. Detection and quantification were performed as described (31).…”