2fl7
From Proteopedia
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S. cerevisiae Sir3 BAH domain
Overview
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.
About this Structure
2FL7 is a Single protein structure of sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.
Reference
Structure of the Sir3 protein bromo adjacent homology (BAH) domain from S. cerevisiae at 1.95 A resolution., Hou Z, Danzer JR, Fox CA, Keck JL, Protein Sci. 2006 May;15(5):1182-6. PMID:16641491
Page seeded by OCA on Wed Nov 21 10:36:53 2007
Categories: Saccharomyces cerevisiae | Single protein | Daner, J.R. | Fox, C.A. | Hou, Z. | Keck, J.L. | Chromatin | Orc | Silencing | Sir
