Structural Studies of RNA Polymerase II transcription initiation and elongation

University Of Pittsburgh At Pittsburgh, Pittsburgh PA

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Abstract

DESCRIPTION (provided by applicant): DNA-directed RNA Polymerase II (Pol II) is one of the most important proteins in the cell. Pol II is responsible for transcribing the vast majority of genes to generate messenger RNA that will be translated in the ribosomes to produce all cellular proteins. The initiation stage of transcription requires timely interactions between Pol I and the general transcription factors or GTFs including, TFIIB, TBP, TFIIF, TFIIH and TFIIE. The process of initiation is highly dynamic; biochemical experiments hint at possible discrete stages where the GTFs recognize, melt and load a nucleic acid scaffold. Initial promoter melting is triggered by TFIIH helicases that generate a 7-9 bases transcription bubble (TB); the bubble is further unwound to approximately 18-25 bases and descends to Pol II's active site where a short DNA-RNA hybrid (transcript) is synthesized; transcripts of 10 or more nucleotides result in promoter escape and stabilization of a mature TB that ultimately leads to dislodging of the GTFs leaving a poised Pol II for entry into productive elongation. This process is universal, for all eukaryotic species, and is at the core of gene regulation; understanding its molecular details will provide essential clues that could potentially lead to pharmacological manipulation of gene expression. The intention of this proposal is to use biochemical and X-ray crystallography techniques to understand the molecular details of promoter binding to Pol II and the role that TFIIB and TFIIF play in TB loading and stabilization.