CSB349L5 - CSB349 Lecture 5 Transcription I: Genome...

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CSB349 Lecture 5 September 27 th , 2010 Transcription I: Genome structure and Transcription The mechanisms of eukaryotic transcription. How does the structure of chromatin influence eukaryotic________________-. Nucleosome remodelling: There are two states a gene can be in. When it’s off, the Nucleosomes and chromatin are neatly packed. When its On, it is loose, the nucleosomes are away from the area Of transcription. How do the genes go from being on from Off? Transcriptional on to transcriptionally off? The topic For today is to address what determines the position And density of the nucleosomes? Ultimately the nucleosoms need to be Moved out of the way to allow for transcription to occur. Chromatin remodelling enzymes (two classes): Class I: They directily modify covalent modification of histone proteins. These modifications indirectly regulate chromatin structure through recruitment of other proteins or directly influence the structure of the nucleus.
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CSB349 Lecture 5 September 27 th , 2010 Class II: They do not directly modify the nucleosomes but they are also ATP-dependent nucleosome multiprotein remodelling complexes (they can move the nucleosomes), directly overcoming the Chemical modifications of histones within nucleosomes These are enzymes that are going to modify the histone tails. Histones form an octomeric structure (two coils of DNA are wrapped in), tails of histone stick out and are available for covalently modifying enzymes. All the modifications occur at these exposed regions. What are these chemical modifications? Phosphorylation, Methylation, Acetylation, Ubiquitination. l The way these go (nomenclature): We’re going to talk about modifications. Histone 3 modification, methylation has been added to lysine 79 would be: H3K79me1. Some can be methylated or acetylated! Must specify Histone, and residue and location of what is affected. Each can have a specific functional
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CSB349L5 - CSB349 Lecture 5 Transcription I: Genome...

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