4iao | pdb_00004iao
Crystal structure of Sir2 C543S mutant in complex with SID domain of Sir4
Structural highlights
Function[SIR2_YEAST] NAD-dependent deacetylase, which participates in a wide range of cellular events including chromosome silencing, chromosome segregation, DNA recombination and the determination of life span. Involved in transcriptional repression of the silent mating-type loci HML and HMR and telomeric silencing via its association with SIR3 and SIR4. Plays a central role in ribosomal DNA (rDNA) silencing via its association with the RENT complex, preventing hyperrecombination, and repressing transcription from foreign promoters, which contributes to extending life span. Probably represses transcription via the formation of heterochromatin structure, which involves the compaction of chromatin fiber into a more condensed form, although this complex in at least one case can still bind euchromatic levels of positive transcription regulators. Although it displays some NAD-dependent histone deacetylase activity on histone H3K9Ac and H3K14Ac and histone H4K16Ac in vitro, such activity is unclear in vivo and may not be essential.[1] [2] [3] [4] [5] [6] [7] [SIR4_YEAST] The proteins SIR1 through SIR4 are required for transcriptional repression of the silent mating type loci, HML and HMR. The proteins SIR2 through SIR4 repress mulitple loci by modulating chromatin structure. Involves the compaction of chromatin fiber into a more condensed form.[8] Publication Abstract from PubMedThe budding yeast Sir2 (silent information regulator 2) protein is the founding member of the sirtuin family of NAD-dependent histone/protein deacetylases. Its function in transcriptional silencing requires both the highly conserved catalytic domain and a poorly understood N-terminal regulatory domain (Sir2N). We determined the structure of Sir2 in complex with a fragment of Sir4, a component of the transcriptional silencing complex in Saccharomyces cerevisiae. The structure shows that Sir4 is anchored to Sir2N and contacts the interface between the Sir2N and the catalytic domains through a long loop. We discovered that the interaction between the Sir4 loop and the interdomain interface in Sir2 is critical for allosteric stimulation of the deacetylase activity of Sir2. These results bring to light the structure and function of the regulatory domain of Sir2, and the knowledge should be useful for understanding allosteric regulation of sirtuins in general. Structural basis for allosteric stimulation of Sir2 activity by Sir4 binding.,Hsu HC, Wang CL, Wang M, Yang N, Chen Z, Sternglanz R, Xu RM Genes Dev. 2013 Jan 1;27(1):64-73. doi: 10.1101/gad.208140.112. PMID:23307867[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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