YinProblemSet2

YinProblemSet2 - Name: Genetics 511 Problem Set 2, due on...

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Name: Genetics 511 Problem Set 2, due on Friday Feb 20, 2009 1. (12 points) (a) Draw a model of the eukaryotic basic transcription machinery on a typical RNA polymerase II core promoter (2 points); (b) Briefly describe the functions of TFIIB, TFIID (TBP and TAFs), TFIIE, TFIIF and TFIIH (6 points). (c) How do transcription activators promote transcription (you don’t have to consider chromatin here, 4 points). (a) (b)TFIIB: links TFIID and RNA polymerase II//TFIIF. Its N terminal domain interacts with Poll II, near the path of RNA exit from transcribing enzyme; a “finger” domain TBP-promoter DNA complex, orients the DNA or unwinding and transcription. TFIIB stabilizes an early initiation complex, containing an incomplete RNA-DNA hybrid region. TBP: binds to the TATA box at the minor groove and bends DNA to start transcription initiation. TAFs: recruit TBP to TATA-less promoter to initiate transcription. TAF II 250 and TAF II 150 bind to GC box. TAF II 250 also has histone acetyltransferase (HAT) and kinase activities that modify chromatin and other transcription factors. TFIIE: stimulates the Pol II CTD phosphorylation by TFIIH. TFIIF: binds to Pol II and interacts with non-template DNA strand. It could bind to Pol II and then direct it to promoters where a DAB complex has already assembles. In this way, TFIIF could lead Pol II to promoters, and away from competing nonspecific DNA sites. TFIIH: phosphorylates Pol II CTD, allowing its escape from the promoter and going on elongation. It also has a DNA helicase activity which is essential for transcription, it causes full melting of the DNA at the promoter.
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(c) Transcription activator contains at least two domains: a DNA binding domain and a transcription activating domain. DNA binding domain can recognize specific DNA
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YinProblemSet2 - Name: Genetics 511 Problem Set 2, due on...

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