Article
- The EMBO Journal (2004) 23, 3836 - 3843
- doi:10.1038/sj.emboj.7600364
Published online: 9 September 2004
Subject Categories:
Reaction cycle of the yeast Isw2 chromatin remodeling complex
Daniel J Fitzgerald, Carl DeLuca, Imre Berger, Hélène Gaillarda, Raphael Sigrist, Kyoko Schimmele and Timothy J Richmond
- ETH Zürich, Institut für Molekularbiologie und Biophysik, ETH-Hönggerberg HPK, Zürich, Switzerland
Correspondence to:
Timothy J Richmond, ETH Zürich, Institut für Molekularbiologie und Biophysik, ETH-Hönggerberg HPK, 8093 Zürich, Switzerland. Tel.: +41 1 633 2470; Fax: +41 1 633 1150; E-mail: richmond@mol.biol.ethz.ch
aPresent address: Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes 6, 41012 Sevilla, Spain
Received 15 April 2004; Accepted 21 July 2004
Abstract
Members of the ISWI family of chromatin remodeling factors hydrolyze ATP to reposition nucleosomes along DNA. Here we show that the yeast Isw2 complex interacts with DNA in a nucleotide-dependent manner at physiological ionic strength. Isw2 efficiently binds DNA in the absence of nucleotides and in the presence of a nonhydrolyzable ATP analog. Conversely, ADP promotes the dissociation of Isw2 from DNA. In contrast, Isw2 remains bound to mononucleosomes through multiple cycles of ATP hydrolysis. Solution studies show that Isw2 undergoes nucleotide-dependent alterations in conformation not requiring ATP hydrolysis. Our results indicate that during an Isw2 remodeling reaction, hydrolysis of successive ATP molecules coincides with cycles of DNA binding, release, and rebinding involving elements of Isw2 distinct from those interacting with nucleosomes. We propose that progression of the DNA-binding site occurs while nucleosome core contacts are maintained and generates a force dissipated by disruption of histone–DNA interactions.
Keywords:
- chromatin remodeling,
- helicase proteins,
- Isw2
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