MBB331_Week10-Fall-2011

Region lewin genes vii 2000 oxford university press

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Unformatted text preview: scription suggesting octamer dissociation not necessary dissociation • add’n of H1 reduces transcription add’n suggesting H1 must be modified or removed from active chromatin or Lewin Genes VII 2000 Oxford University Press 29 SV40 NUCLEOSOME­FREE SV40 NUCLEOSOME­FREE ZONES • Some regulatory DNA Some regions too stiff for nucleosome formation nucleosome • Nucleosome-free zones Nucleosome-free identified in control regions of active genes regions • SV40 minichromosome SV40 visible nucleosome-free gap that corresponds to nuclease-sensitive region…. region…. Lewin Genes VII 2000 Oxford University Press 30 DNase HYPERSENSITIVE SITES DNase • Chromatin exposed by Chromatin transcription or structural changes susceptible to digestion by low DNase I concentration concentration • DNase I hypersensitive DNase sites: 100X more sensitive to DNase I to • Chromatin DNase I treated Chromatin --> DNA isolated --> distance from known restriction site determines hypersensitive site 31 Lewin Genes VII 2000 Oxford University Press TRANSCRIPTION AIDED BY NUCLEOSOME TRANSCRIPTION POSITIONING • Nucleosomes not necessarily Nucleosomes hindrance to transcription - ie. ie positioning nucleosomes with respect to regulatory sites respect • Mouse mammary tumor virus Mouse (MMTV) promoter: 3 sites for dimeric hormone receptors, and NF1 & OTF-1 sites NF1 • Naked DNA ---> NF1...
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