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Crystal Structure of the Coiled-coil Dimerization Motif of Sir4Crystal Structure of the Coiled-coil Dimerization Motif of Sir4
Structural highlights
Function[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.[1] Publication Abstract from PubMedThe yeast silent information regulators Sir2, Sir3, and Sir4 physically interact with one another to establish a transcriptionally silent state by forming repressive chromatin structures. The Sir4 protein contains binding sites for both Sir2 and Sir3, and these protein-protein interactions are required for gene silencing. Here, we report the X-ray structure of the coiled-coil dimerization motif within the C-terminus of Sir4 and show that it forms a stable 1:1 complex with a dimeric fragment of Sir3 (residues 464-978). We have identified a cluster of residues on the surface of the Sir4 coiled coil required for specific interactions with Sir3. The histone deacetylase Sir2 can also bind to this complex, forming a ternary complex with the truncated Sir3 and Sir4 proteins. The dual interactions of Sir4 with Sir3 and Sir2 suggest a physical basis for recruiting Sir3 to chromatin by virtue of its interactions with Sir4 and with deacetylated histones in chromatin. Structure of the coiled-coil dimerization motif of Sir4 and its interaction with Sir3.,Chang JF, Hall BE, Tanny JC, Moazed D, Filman D, Ellenberger T Structure. 2003 Jun;11(6):637-49. PMID:12791253[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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