Chemistry of Gene Silencing: The Mechanism of NAD+-Dependent Deacetylation Reactions
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- 作者：Anthony A. Sauve ; Ivana Celic ; Jose Avalos ; Haiteng Deng ; Jef D. Boeke ; and Vern L. Schramm
- 刊名：Biochemistry
- 出版年：2001
- 出版时间：December 25, 2001
- 年：2001
- 卷：40
- 期：51
- 页码：15456 - 15463
- 全文大小：264K
- 年卷期：v.40,no.51(December 25, 2001)
- ISSN：1520-4995
文摘
The Sir2 enzyme family is responsible for a newly classified chemical reaction, NAD+-dependent protein deacetylation. New peptide substrates, the reaction mechanism, and the products of theacetyl transfer to NAD+ are described for SIR2. The final products of SIR2 reactions are the deacetylatedpeptide and the 2' and 3' regioisomers of O-acetyl ADP ribose (AADPR), formed through an 
-1'-acetylADP ribose intermediate and intramolecular transesterification reactions (2' 
3'). The regioisomers,their anomeric forms, the interconversion rates, and the reaction equilibria were characterized by NMR,HPLC, 18O exchange, and MS methods. The mechanism of acetyl transfer to NAD+ includes (1) ADPribosylation of the peptide acyl oxygen to form a high-energy O-alkyl amidate intermediate, (2) attack ofthe 2'-OH group on the amidate to form a 1',2'-acyloxonium species, (3) hydrolysis to 2'-AADPR by theattack of water on the carbonyl carbon, and (4) an SIR2-independent transesterification equilibrating the2'- and 3'-AADPRs. This mechanism is unprecedented in ADP-ribosyl transferase enzymology. The 2'-and 3'-AADPR products are candidate molecules for SIR2-initiated signaling pathways.
-1'-acetylADP ribose intermediate and intramolecular transesterification reactions (2' 3'). The regioisomers,their anomeric forms, the interconversion rates, and the reaction equilibria were characterized by NMR,HPLC, 18O exchange, and MS methods. The mechanism of acetyl transfer to NAD+ includes (1) ADPribosylation of the peptide acyl oxygen to form a high-energy O-alkyl amidate intermediate, (2) attack ofthe 2'-OH group on the amidate to form a 1',2'-acyloxonium species, (3) hydrolysis to 2'-AADPR by theattack of water on the carbonyl carbon, and (4) an SIR2-independent transesterification equilibrating the2'- and 3'-AADPRs. This mechanism is unprecedented in ADP-ribosyl transferase enzymology. The 2'-and 3'-AADPR products are candidate molecules for SIR2-initiated signaling pathways.