Hydrolase controls cellular NAD, sirtuin, and secondary metabolites.
Cellular levels of NAD(+) and NADH are thought to be controlled by de novo and salvage mechanisms, although evidence has not yet indicated that they are regulated by NAD(+) degradation. Here we show that the conserved nudix hydrolase isozyme NdxA hydrolyzes and decreases cellular NAD(+) and NADH in Aspergillus nidulans. The NdxA-deficient fungus accumulated more NAD(+) during the stationary growth phase, indicating that NdxA maintains cellular NAD(+)/NADH homeostasis. The deficient strain also generated less of the secondary metabolites sterigmatocystin and penicillin G and of their gene transcripts than did the wild type. These defects were associated with a reduction in acetylated histone H4 on the gene promoters of aflR and ipnA that are involved in synthesizing secondary metabolites. Thus, NdxA increases acetylation levels of histone H4. We discovered that the novel fungal sirtuin isozyme SirA uses NAD(+) as a cosubstrate to deacetylate the lysine 16 residue of histone H4 on the gene promoter and represses gene expression. The impaired acetylation of histone and secondary metabolite synthesis in the NdxA-deficient strain were restored by eliminating functional SirA, indicating that SirA mediates NdxA-dependent regulation. These results indicated that NdxA controls total levels of NAD(+)/NADH and negatively regulates sirtuin function and chromatin structure.
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Motoyuki
M
Shimizu
Shunsuke
S
Masuo
Tomoya
T
Fujita
Yuki
Y
Doi
Yosuke
Y
Kamimura
Naoki
N
Takaya
D000107:Acetylation; D001233:Aspergillus nidulans / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics; D010400:Penicillin G / Q000032:analysis; D011401:Promoter Regions, Genetic; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D037761:Sirtuins / Q000378:metabolism*; D013241:Sterigmatocystin / Q000032:analysis; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D000096964:Nudix Hydrolases
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006657:Histones; D006867:Hydrolases; D009243:NAD; D010088:Oxidoreductases; D010400:Penicillin G; D011755:Pyrophosphatases; D037761:Sirtuins; D013241:Sterigmatocystin; D014157:Transcription Factors; D000096964:Nudix Hydrolases; C113837:AFLR protein, Aspergillus; C038370:isopenicillin N synthetase