Dynamics and function of compact nucleosome arrays.

Full Abstract

The packaging of eukaryotic DNA into chromatin sterically occludes polymerases, recombinases and repair enzymes. How chromatin structure changes to allow their actions is unknown. We constructed defined fluorescently labeled trinucleosome arrays, allowing analysis of chromatin conformational dynamics via fluorescence resonance energy transfer (FRET). The arrays undergo reversible Mg2+-dependent folding similar to that of longer arrays studied previously. We define two intermediate conformational states in the reversible folding of the nucleosome arrays and characterize the microscopic rate constants. Nucleosome arrays are highly dynamic even when compact, undergoing conformational fluctuations on timescales in the second to microsecond range. Compact states of the arrays allow binding to DNA within the central nucleosome via site exposure. Protein binding can also drive decompaction of the arrays. Thus, our results reveal multiple modes by which spontaneous chromatin fiber dynamics allow for the invasion and action of DNA-processing protein complexes.

Author information

Author/s: Poirier, Michael G (MG); Oh, Eugene (E); Tims, Hannah S (HS); Widom, Jonathan (J);

Affiliation: Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois, USA.

Grants: F32 GM072306 (Agency:NIGMS NIH HHS) ; R01 GM54692 (Agency:NIGMS NIH HHS) ; R01 GM58617 (Agency:NIGMS NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Nature structural & molecular biology (Nat Struct Mol Biol), published in United States. (Language: eng)

Reference: 2009-Sep; vol 16 (issue 9) : pp 938-44

Dates: Created 2009/09/03; Completed 2009/09/25;

PMID: 19701201, status: MEDLINE (last retrieval date: 9/25/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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