title: NAD+-dependent deacetylase Hst1p controls biosynthesis and cellular NAD+ levels in Saccharomyces cerevisiae.
abstract: Nicotine adenine dinucleotide (NAD(+)) performs key roles in electron transport reactions, as a substrate for poly(ADP-ribose) polymerase and NAD(+)-dependent protein deacetylases. In the latter two processes, NAD(+) is consumed and converted to ADP-ribose and nicotinamide. NAD(+) levels can be maintained by regeneration of NAD(+) from nicotinamide via a salvage pathway or by de novo synthesis of NAD(+) from tryptophan. Both pathways are conserved from yeast to humans. We describe a critical role of the NAD(+)-dependent deacetylase Hst1p as a sensor of NAD(+) levels and regulator of NAD(+) biosynthesis. Using transcript arrays, we show that low NAD(+) states specifically induce the de novo NAD(+) biosynthesis genes while the genes in the salvage pathway remain unaffected. The NAD(+)-dependent deacetylase activity of Hst1p represses de novo NAD(+) biosynthesis genes in the absence of new protein synthesis, suggesting a direct effect. The known Hst1p binding partner, Sum1p, is present at promoters of highly inducible NAD(+) biosynthesis genes. The removal of HST1-mediated repression of the NAD(+) de novo biosynthesis pathway leads to increased cellular NAD(+) levels. Transcript array analysis shows that reduction in cellular NAD(+) levels preferentially affects Hst1p-regulated genes in comparison to genes regulated with other NAD(+)-dependent deacetylases (Sir2p, Hst2p, Hst3p, and Hst4p). In vitro experiments demonstrate that Hst1p has relatively low affinity toward NAD(+) in comparison to other NAD(+)-dependent enzymes. These findings suggest that Hst1p serves as a cellular NAD(+) sensor that monitors and regulates cellular NAD(+) levels.
authors.affiliation: Clinical Research and Human Biology Divisions, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA. abedalow@fhcrc.org
authors.forename: Antonio
authors.initials: A
authors.lastname: Bedalov
authors.forename: Maki
authors.initials: M
authors.lastname: Hirao
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Posakony
authors.forename: Melisa
authors.initials: M
authors.lastname: Nelson
authors.forename: Julian A
authors.initials: JA
authors.lastname: Simon
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005982:Glutathione Transferase / Q000378:metabolism; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D009243:NAD / Q000378:metabolism*; D009536:Niacinamide / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D037761:Sirtuins / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D006657:Histones; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C100925:SUM1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D009536:Niacinamide; D005982:Glutathione Transferase; D037761:Sirtuins; D006655:Histone Deacetylases