2qqg | pdb_00002qqg
Hst2 bound to ADP-HPD, acetyllated histone H4 and nicotinamide
Structural highlights
FunctionHST2_YEAST NAD-dependent histone deacetylase that is involved in nuclear silencing events. Derepresses subtelomeric silencing and increases repression in nucleolar (rDNA) silencing. Its function is negatively regulated by active nuclear export.[1] [2] [3] [4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe Sir2 family of proteins consists of broadly conserved NAD(+)-dependent deacetylases that are implicated in diverse biological processes, including DNA regulation, metabolism, and longevity. Sir2 proteins are regulated in part by the cellular concentrations of a noncompetitive inhibitor, nicotinamide, that reacts with a Sir2 reaction intermediate via a base-exchange reaction to reform NAD(+) at the expense of deacetylation. To gain a mechanistic understanding of nicotinamide inhibition in Sir2 enzymes, we captured the structure of nicotinamide bound to a Sir2 homolog, yeast Hst2, in complex with its acetyl-lysine 16 histone H4 substrate and a reaction intermediate analog, ADP-HPD. Together with related biochemical studies and structures, we identify a nicotinamide inhibition and base-exchange site that is distinct from the so-called "C pocket" binding site for the nicotinamide group of NAD(+). These results provide insights into the Sir2 mechanism of nicotinamide inhibition and have important implications for the development of Sir2-specific effectors. Structural basis for nicotinamide inhibition and base exchange in Sir2 enzymes.,Sanders BD, Zhao K, Slama JT, Marmorstein R Mol Cell. 2007 Feb 9;25(3):463-72. PMID:17289592[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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