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| - | [[Image:1pl5.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1pl5| PDB=1pl5 | SCENE= }} | | {{STRUCTURE_1pl5| PDB=1pl5 | SCENE= }} |
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| - | '''Crystal Structure Analysis of the Sir4p C-terminal Coiled Coil'''
| + | ===Crystal Structure Analysis of the Sir4p C-terminal Coiled Coil=== |
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| - | ==Overview==
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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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_14636601}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 14636601 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_14636601}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Spedale, E J.]] | | [[Category: Spedale, E J.]] |
| | [[Category: Parallel coiled coil homodimer]] | | [[Category: Parallel coiled coil homodimer]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:12:46 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 17:49:34 2008'' |
Revision as of 14:49, 27 July 2008
Template:STRUCTURE 1pl5
Crystal Structure Analysis of the Sir4p C-terminal Coiled Coil
Template:ABSTRACT PUBMED 14636601
About this Structure
1PL5 is a Single protein structure of sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.
Reference
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
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