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Nucleosomes inhibit transcription by preventing the binding of RNA polymerase II and the general transcription factors to promoter DNA. This inhibition is relieved when promoter chromatin is remodeled to render the DNA accessible for transcription. Here we show that the chromatin remodeling factor Chd1 selectively remodels promoter nucleosomes. Chromatin circles of the repressed PHO5 gene, containing both promoter and open reading frame (ORF), were remodeled by yeast extract in a gene activator-dependent, ATP-dependent manner. The product of the reaction bore the hallmark of the process in vivo, the selective removal of promoter nucleosomes, without effect on ORF nucleosomes. Fractionation of the extract identified a single protein, Chd1, capable of the remodeling activity. Our results show that a single enzyme, Chd1, can distinguish between native promoter and ORF nucleosomes. In agreement with previous observations in yeast and in higher eukaryotes, we speculate that Chd1 may recognize histone marks specific to promoters and play a general role in gene activation via the establishment of open promoter chromatin.

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Andreas was born in Mexico City, where he developed an early interest in Biology. He then moved to California, where he studied aldo-keto reductases under the mentorship of Dave Wilson at UC Davis. Andreas then completed his doctorate under Roger Kornberg at Stanford to reconstitute the remodeling of native chromatin. He is now at CRUK in London.

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