Nucleosome Remodeling Factor NURF and In Vitro Transcription of Chromatin

A central problem in the control of eukaryotic gene expression is how the compaction of DNA in chromatin is overcome to allow the initiation and elongation of transcription (1 –6 ). Current studies reveal that multiple mechanisms are involved in counteracting chromatin-mediated repression, including DNA structure, histone modification, and the action of nonhistone regulators of nucleosome structure (7 –14 ). Recently, novel chromatin remodeling factors: the SWI/SNF complex, RSC, NURF, CHRAC, and ACF have been isolated, whose action is dependent on the energy of ATP hydrolysis (15 –20 ). Here we present an integrated chromatin assembly-transcription system (21 –23 ) whereby the functional consequences of such nucleosome remodeling activities may be analyzed by in vitro transcription of reconstituted chromatin templates devoid of endogenous ATP-dependent nucleosome remodeling activities. We also describe procedures that reveal transcriptional activation of chromatin mediated by a chimeric DNA-binding activator GAL4-HSF and the Drosophila Nucleosome Remodeling Factor NURF (24 ).