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| ==Crystal Structure Analysis of the Sir4p C-terminal Coiled Coil== | | ==Crystal Structure Analysis of the Sir4p C-terminal Coiled Coil== |
| <StructureSection load='1pl5' size='340' side='right' caption='[[1pl5]], [[Resolution|resolution]] 2.50Å' scene=''> | | <StructureSection load='1pl5' size='340' side='right'caption='[[1pl5]], [[Resolution|resolution]] 2.50Å' scene=''> |
| == Structural highlights == | | == Structural highlights == |
| <table><tr><td colspan='2'>[[1pl5]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PL5 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1PL5 FirstGlance]. <br> | | <table><tr><td colspan='2'>[[1pl5]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PL5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1PL5 FirstGlance]. <br> |
| </td></tr><tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">SIR4 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 Saccharomyces cerevisiae])</td></tr> | | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5Å</td></tr> |
| <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1pl5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pl5 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1pl5 RCSB], [http://www.ebi.ac.uk/pdbsum/1pl5 PDBsum]</span></td></tr> | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1pl5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1pl5 OCA], [https://pdbe.org/1pl5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1pl5 RCSB], [https://www.ebi.ac.uk/pdbsum/1pl5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1pl5 ProSAT]</span></td></tr> |
| </table> | | </table> |
| == Function == | | == Function == |
| [[http://www.uniprot.org/uniprot/SIR4_YEAST 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.<ref>PMID:18039933</ref> | | [https://www.uniprot.org/uniprot/SIR4_YEAST 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.<ref>PMID:18039933</ref> |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| Saccharomyces cerevisiae Sir4p plays important roles in silent chromatin at telomeric and silent mating type loci. The C terminus of Sir4p (Sir4CT) is critical for its functions in vivo because over-expression or deletion of Sir4CT fragments disrupts normal telomeric structure and abolishes the telomere position effect. The 2.5A resolution X-ray crystal structure of an Sir4CT fragment (Sir4p 1217-1358) reveals a 72 residue homodimeric, parallel coiled coil, burying an extensive 3600A(2) of surface area. The crystal structure is consistent with results of protein cross-linking and analytical ultracentrifugation results demonstrating that Sir4CT exists as a dimer in solution. Disruption of the coiled coil in vivo by point mutagenesis results in total derepression of telomeric and HML silent mating marker genes, suggesting that coiled coil dimerization is essential for Sir4p-mediated silencing. In addition to the coiled coil dimerization interface (Sir4CC interface), a crystallographic interface between pairs of coiled coils is significantly hydrophobic and buries 1228A(2) of surface area (interface II). Remarkably, interface II mutants are deficient in telomeric silencing but not in mating type silencing in vivo. However, point mutants of interface II do not affect the oligomerization state of Sir4CT in solution. These results are consistent with the hypothesis that interface II mimics a protein interface between Sir4p and one of its protein partners that is essential for telomeric silencing but not mating type silencing.
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| The Sir4 C-terminal coiled coil is required for telomeric and mating type silencing in Saccharomyces cerevisiae.,Murphy GA, Spedale EJ, Powell ST, Pillus L, Schultz SC, Chen L J Mol Biol. 2003 Dec 5;334(4):769-80. PMID:14636601<ref>PMID:14636601</ref>
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| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| == References == | | == References == |
| <references/> | | <references/> |
| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |
| | [[Category: Large Structures]] |
| [[Category: Saccharomyces cerevisiae]] | | [[Category: Saccharomyces cerevisiae]] |
| [[Category: Chen, L]] | | [[Category: Chen L]] |
| [[Category: Murphy, G A]] | | [[Category: Murphy GA]] |
| [[Category: Pillus, L]] | | [[Category: Pillus L]] |
| [[Category: Powell, S T]] | | [[Category: Powell ST]] |
| [[Category: Schultz, S C]] | | [[Category: Schultz SC]] |
| [[Category: Spedale, E J]] | | [[Category: Spedale EJ]] |
| [[Category: Dna binding protein-transcription complex]]
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| [[Category: Parallel coiled coil homodimer]]
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