1ZBX

Crystal structure of a Orc1p-Sir1p complex

Summary for 1ZBX

• Entry DOI: 10.2210/pdb1zbx/pdb
• Related: 1M4Z
• Descriptor: Origin recognition complex subunit 1, Regulatory protein SIR1 (3 entities in total)
• Functional Keywords: protein-protein interaction, epigenetics, silencing, silent information regulators, transcription
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Cellular location: Nucleus: P54784 P21691
• Total number of polymer chains: 2
• Total formula weight: 42213.38

Authors

Hsu, H.C.,Stillman, B.,Xu, R.M. (deposition date: 2005-04-09, release date: 2005-06-21, Last modification date: 2024-02-14)

Primary citation

Hsu, H.C.,Stillman, B.,Xu, R.M.
Structural basis for origin recognition complex 1 protein-silence information regulator 1 protein interaction in epigenetic silencing
Proc.Natl.Acad.Sci.USA, 102:8519-8524, 2005

PubMed Abstract: The interaction between silence information regulator 1 protein (Sir1p) and origin recognition complex 1 protein (Orc1p), the largest subunit of the origin recognition complex, plays an important role in the establishment of transcriptional silencing at the cryptic mating-type gene loci in Saccharomyces cerevisiae. Sir1p binds the N-terminal region of Orc1p encompassing a Bromo-adjacent homology (BAH) domain found in various chromatin-associated proteins. To understand the molecular mechanism of Sir protein recruitment, we have determined a 2.5-A cocrystal structure of the N-terminal domain of Orc1p in complex with the Orc1p-interacting domain of Sir1p. The structure reveals that Sir1p Orc1p-interacting domain has a bilobal structure: an alpha/beta N-terminal lobe and a C-terminal lobe resembling the Tudor domain royal family fold. The N-terminal lobe of Sir1p binds in a shallow groove between a helical subdomain and the BAH domain of Orc1p. The structure provides a mechanistic understanding of Orc1p-Sir1p interaction specificity, as well as insights into protein-protein interactions involving BAH domains in general.

PubMed: 15937111
DOI: 10.1073/pnas.0502946102

Experimental method

X-RAY DIFFRACTION (2.5 Å)