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| {{STRUCTURE_2fl7| PDB=2fl7 | SCENE= }} | | {{STRUCTURE_2fl7| PDB=2fl7 | SCENE= }} |
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| '''S. cerevisiae Sir3 BAH domain'''
| | ===S. cerevisiae Sir3 BAH domain=== |
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| ==Overview==
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| Sir3p is a silent-information-regulator (SIR) protein required for the assembly of a transcriptionally "silent" chromatin structure at telomeres and the cryptic HM mating-type loci in Saccharomyces cerevisiae. Sir3p contains a putative "bromo adjacent homology" (BAH) domain at its N terminus that shares strong sequence similarity with the BAH domain of a subunit of the origin recognition complex (ORC), Orc1p. The Orc1p-BAH domain forms a well-defined complex with the ORC interaction region (OIR) of another Sir protein, Sir1p, which targets formation of silent chromatin to the HM-loci. Interestingly, despite sequence similarity of the Sir3p and Orc1p BAH domains and Sir3p's established importance in silencing, Sir3p does not bind the Sir1p-OIR. Here we report the 1.95 A resolution crystal structure of the Sir3p-BAH domain. The structure reveals two key features that can account for Sir3p-BAH domain's inability to interact with Sir1p. First, several Orc1p-BAH domain residues known to directly contact Sir1p are altered in the Sir3p-BAH domain. Second, a critical OIR-binding pocket present on the surface of the Orc1p-BAH domain is "filled" in the Sir3p-BAH domain structure, potentially making it inaccessible to Sir1p. These findings imply that the Sir3p-BAH domain structure has evolved for functions distinct from those of the Orc1p-BAH domain.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16641491}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16641491 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16641491}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Silencing]] | | [[Category: Silencing]] |
| [[Category: Sir]] | | [[Category: Sir]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 04:01:21 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 12:36:14 2008'' |
