4bvh | pdb_00004bvh
CRYSTAL STRUCTURE OF HUMAN SIRT3 IN COMPLEX WITH THE INHIBITOR EX-527 AND 2'-O-ACETYL-ADP-RIBOSE
Structural highlights
Function[SIR3_HUMAN] NAD-dependent protein deacetylase. Activates mitochondrial target proteins, including ACSS1, IDH2 and GDH by deacetylating key lysine residues. Contributes to the regulation of the cellular energy metabolism. Important for regulating tissue-specific ATP levels.[1] [2] [3] [4] Publication Abstract from PubMedSirtuins are protein deacetylases regulating metabolism and stress responses. The seven human Sirtuins (Sirt1-7) are attractive drug targets, but Sirtuin inhibition mechanisms are mostly unidentified. We report the molecular mechanism of Sirtuin inhibition by 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide (Ex-527). Inhibitor binding to potently inhibited Sirt1 and Thermotoga maritima Sir2 and to moderately inhibited Sirt3 requires NAD+, alone or together with acetylpeptide. Crystal structures of several Sirtuin inhibitor complexes show that Ex-527 occupies the nicotinamide site and a neighboring pocket and contacts the ribose of NAD+ or of the coproduct 2'-O-acetyl-ADP ribose. Complex structures with native alkylimidate and thio-analog support its catalytic relevance and show, together with biochemical assays, that only the coproduct complex is relevant for inhibition by Ex-527, which stabilizes the closed enzyme conformation preventing product release. Ex-527 inhibition thus exploits Sirtuin catalysis, and kinetic isoform differences explain its selectivity. Our results provide insights in Sirtuin catalysis and inhibition with important implications for drug development. Ex-527 inhibits Sirtuins by exploiting their unique NAD+-dependent deacetylation mechanism.,Gertz M, Fischer F, Nguyen GT, Lakshminarasimhan M, Schutkowski M, Weyand M, Steegborn C Proc Natl Acad Sci U S A. 2013 Jul 9. PMID:23840057[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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