The packaging of DNA into chromatin makes it largely inaccessible for the central nuclear processes of transcription, replication, recombination and repair. ATP-dependent chromatin remodeling motors play key roles in both increasing DNA access within chromatin as well in generating higher-order chromatin structures that promote transcriptional repression. However, the mechanisms by which chromatin remodeling motors function are largely unknown. The overall goal of this proposal is to use concepts learnt from well-studied motors such as kinesin and helicases to understand how a major ATP dependent chromatin-remodeling complex, human ACF functions. ACF functions as a dimeric motor to generate evenly spaced nucleosomes. The ordered nucleosome spacing enables higher-order chromatin folding and gene silencing. Our work over the current grant period has led to the unexpected finding that ACF used ATP to induce substantial distortions within an intact histone octamer. We have further found that coordination between the two ATPase protomers within a dimeric ACF relies on specific recognition of nucleosomal cues. Here we will build on these discoveries to address the following fundamental questions: (1) How does ACF use the energy of ATP to distort nucleosome conformation and how is this distortion coupled to nucleosome movement? (2) How are the activities of the two ACF promoters coordinated and how are substrate cues used in this process?

Public Health Relevance

ACF complexes play crucial roles in mediating heritable gene silencing and DNA repair. Consistent with these roles, mutations in the components of ACF complexes are associated with severe developmental defects and specific cancers. A detailed understanding of ACF mechanism will provide insights into how its activity is regulated and how it malfunctions

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM073767-12
Application #
9187456
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Preusch, Peter
Project Start
2005-04-01
Project End
2018-11-30
Budget Start
2016-12-01
Budget End
2017-11-30
Support Year
12
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of California San Francisco
Department
Biochemistry
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94118
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Sinha, Kalyan K; Gross, John D; Narlikar, Geeta J (2017) Distortion of histone octamer core promotes nucleosome mobilization by a chromatin remodeler. Science 355:
Zhou, Coral Y; Stoddard, Caitlin I; Johnston, Jonathan B et al. (2017) Regulation of Rvb1/Rvb2 by a Domain within the INO80 Chromatin Remodeling Complex Implicates the Yeast Rvbs as Protein Assembly Chaperones. Cell Rep 19:2033-2044
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Isaac, R Stefan; Jiang, Fuguo; Doudna, Jennifer A et al. (2016) Nucleosome breathing and remodeling constrain CRISPR-Cas9 function. Elife 5:
Zhou, C Y; Narlikar, G J (2016) Analysis of Nucleosome Sliding by ATP-Dependent Chromatin Remodeling Enzymes. Methods Enzymol 573:119-35
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Racki, Lisa R; Naber, Nariman; Pate, Ed et al. (2014) The histone H4 tail regulates the conformation of the ATP-binding pocket in the SNF2h chromatin remodeling enzyme. J Mol Biol 426:2034-44

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