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Mis16 Switches Function from a Histone H4 Chaperone to a CENP-ACnp1-Specific Assembly Factor through Eic1 Interaction
Sojin An1, Philipp Koldewey2, Jennifer Chik3
1Department of Biological Chemistry, University of Michigan Medical School, 1150 W. Medical Center Drive, SPC 5606, Ann Arbor, MI 48109, USA.
Structure (London, England : 1993)
|May 29, 2018
Summary
The Mis18 complex
Area of Science:
- Cell Biology
- Molecular Biology
- Epigenetics
Background:
- The Mis18 complex is crucial for depositing CENP-ACnp1 at centromeres.
- The oligomerization and centromere-specific function of Mis16 within the Mis18 complex are not well understood.
Purpose of the Study:
- To elucidate the stoichiometry of the Mis18 holo-complex.
- To determine the molecular mechanism by which Mis16 achieves centromere specificity.
Main Methods:
- Analytical ultracentrifugation to determine complex stoichiometry.
- X-ray crystallography to determine the structure of Mis16 in complex with Eic1.
Main Results:
- The stoichiometry of the Mis18 holo-complex was determined to be (Mis16)2:(Eic1)2:(Mis18)4.
- The crystal structure revealed that Mis16 binds Eic1-CT in the same pocket used for histone H4.
- This competition explains how Mis16 switches binding partners.
Conclusions:
- The study defines the precise stoichiometry of the Mis18 holo-complex.
- A molecular mechanism for Mis16's centromere-specific role, involving competition with histone H4 for binding to Eic1, has been uncovered.
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