Influence of RNA Polymerase II Catalytic Activity on Transcription Start Site Selection
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RNA Polymerase II (Pol II) is responsible for expression of all protein-coding genes in eukaryotes. To understand gene expression at the molecular level, it is essential to understand the mechanisms of Pol II function. I investigate how Pol II catalytic activity influences the first step of gene expression, transcription initiation, in Saccharomyces cerevisiae. My dissertation focuses on the mechanisms by which Pol II activity defects contribute to transcription start site (TSS) selection/utilization and promoter output. I utilize mutants with substitutions in the Pol II active site that have different elongation rates in vitro and show varied growth phenotypes in vivo that correlate with the observed alterations in elongation rates. I employ genetic and biochemical approaches to investigate the relationships between the TSS phenotypes of Pol II activity/General Transcription Factor (GTF) mutants and conditional and general growth phenotypes. I show that while some conditional growth phenotypes correlate closely with TSS defects, TSS defects are not likely the main determinant for general growth defects. I further explore growth phenotypes and TSS defects between Pol II genetic interactors and GTF mutants combined with Pol II activity mutants and present different models for the relationships discovered so far. I discover a novel function of Sub1, which is suggested to play positive roles in transcription as an initiation factor, altering TSS utilization on its own and modifying TSS defects conferred by Pol II activity mutants. I take a genome wide approach to map TSSs, general transcription factor occupancies, and nucleosome positions to investigate the mechanism of Pol II activity control over initiation, and determine how promoter architecture influences TSS selection/utilization and nucleosome positioning. I show that promoter architecture is a critical parameter in determination of various initiation properties including transcription output (gene expression) levels.
SubjectTranscription Start Site selection
Jin, Huiyan (2015). Influence of RNA Polymerase II Catalytic Activity on Transcription Start Site Selection. Doctoral dissertation, Texas A & M University. Available electronically from