dCHD3 – a novel ATP-dependent chromatin remodeler associated with sites of active transcription

Institut für Molekularbiologie und Tumorforschung, University of Marburg, 35033 Marburg, Germany; Nijmegen Centre for Molecular Life Sciences, Molecular Biology Department, Radboud University, Nijmegen, Netherlands; Biochemie III, University of Regensburg, 93053 Regensburg, Germany; GSF-Forschungszentrum, Institut für Molekulare Immunologie, 81377 München, Germany

^* To whom correspondence should be addressed. Email: brehm{at}imt.uni-marburg.de.

	Abstract

ATP dependent chromatin remodelers of the CHD family play important roles during differentiation and development. Three CHD proteins, dMi-2, dChd1 and Kismet, have been described in D.melanogaster. Here, we study dCHD3, a novel member of the CHD family. dCHD3 is related in sequence to dMi-2 but lacks several domains implicated in dMi-2 function. We demonstrate that dCHD3 is a nuclear protein and that expression is tightly regulated during fly development. Recombinant dCHD3 remodels mono- and polynucleosomes in an ATP-dependent manner in vitro. Its chromodomains are critical for nucleosome binding and remodeling. Unlike dMi-2, dCHD3 exists as a monomer. Nevertheless, both proteins colocalise with RNA polymerase II to actively transcribed regions on polytene chromosomes suggesting that both remodelers participate in the process of transcription.