title: The Transcription Factor THO Promotes Transcription Initiation and Elongation by RNA Polymerase I.
abstract: Although ribosomal RNA represents the majority of cellular RNA, and ribosome synthesis is closely connected to cell growth and proliferation rates, a complete understanding of the factors that influence transcription of ribosomal DNA is lacking. Here, we show that the THO complex positively affects transcription by RNA polymerase I (Pol I). We found that THO physically associates with the rDNA repeat and interacts genetically with Pol I transcription initiation factors. Pol I transcription in hpr1 or tho2 null mutants is dramatically reduced to less than 20% of the WT level. Pol I occupancy of the coding region of the rDNA in THO mutants is decreased to ~50% of WT level. Furthermore, although the percentage of active rDNA repeats remains unaffected in the mutant cells, the overall rDNA copy number increases ~2-fold compared with WT. Together, these data show that perturbation of THO function impairs transcription initiation and elongation by Pol I, identifying a new cellular target for the conserved THO complex.
authors.affiliation: From the Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0024 and.
authors.forename: Yinfeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: the Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: French
authors.affiliation: the Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908.
authors.forename: Ann L
authors.initials: AL
authors.lastname: Beyer
authors.affiliation: From the Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294-0024 and dschneid@uab.edu.
authors.forename: David A
authors.initials: DA
authors.lastname: Schneider
mesh_terms: D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D012318:RNA Polymerase I / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D061805:Transcription Elongation, Genetic / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D061785:Transcription Initiation, Genetic / Q000502:physiology*
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal; C063494:HPR1 protein, S cerevisiae; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C405934:THO2 protein, S cerevisiae; D014157:Transcription Factors; D012318:RNA Polymerase I
keywords: RNA polymerase I; gene expression; ribosomal RNA processing (rRNA processing); ribosome; transcription