Insights into the Sirtuin Mechanism from Ternary Complexes Containing NAD+ and Acetylated Peptide

Kevin G. Hoff, Jose L. Avalos, Kristin Sens, Cynthia Wolberger

Research output: Contribution to journalArticle

100 Scopus citations

Abstract

Sirtuin proteins comprise a unique class of NAD+-dependent protein deacetylases. Although several structures of sirtuins have been determined, the mechanism by which NAD+ cleavage occurs has remained unclear. We report the structures of ternary complexes containing NAD+ and acetylated peptide bound to the bacterial sirtuin Sir2Tm and to a catalytic mutant (Sir2TmH116Y). NAD+ in these structures binds in a conformation different from that seen in previous structures, exposing the α face of the nicotinamide ribose to the carbonyl oxygen of the acetyl lysine substrate. The NAD+ conformation is identical in both structures, suggesting that proper coenzyme orientation is not dependent on contacts with the catalytic histidine. We also present the structure of Sir2TmH116A bound to deacteylated peptide and 3′-O-acetyl ADP ribose. Taken together, these structures suggest a mechanism for nicotinamide cleavage in which an invariant phenylalanine plays a central role in promoting formation of the O-alkylamidate reaction intermediate and preventing nicotinamide exchange.

Original languageEnglish (US)
Pages (from-to)1231-1240
Number of pages10
JournalStructure
Volume14
Issue number8
DOIs
StatePublished - Aug 2006

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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