2fl7

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spinqualitylabelsall models PDB ID 2fl7 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 1.85Å
Gene:	SIR3, CMT1, MAR2, STE8 (Saccharomyces cerevisiae)
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

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

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