title: Rrn7 protein, an RNA polymerase I transcription factor, is required for RNA polymerase II-dependent transcription directed by core promoters with a HomolD box sequence.
abstract: The region in promoters that specifies the transcription machinery is called the core promoter, displaying core promoter elements (CPE) necessary for establishment of a preinitiation complex and the initiation of transcription. A classical CPE is the TATA box. In fission yeast, Schizosaccharomyces pombe, a new CPE, called HomolD box, was discovered. Collectively, 141 ribosomal protein genes encoding the full set of 79 different ribosomal proteins and more than 60 other housekeeping genes display a HomolD box in the core promoter. Here, we show that transcription directed by the HomolD box requires the RNA polymerase II machinery, including the general transcription factors. Most intriguingly, however, we identify, by DNA affinity purification, Rrn7 as the protein binding to the HomolD box. Rrn7 is an evolutionary conserved member of the RNA polymerase I machinery involved in transcription initiation of core ribosomal DNA promoters. ChIP shows that Rrn7 cross-links to a ribosomal protein gene promoter containing the HomolD box but not to a promoter containing a TATA box. Taken together, our results suggest that Rrn7 is an excellent candidate to be involved in the coordination of ribosomal DNA and ribosomal gene transcription during ribosome synthesis and, therefore, offer a new perspective to study conservation and evolvability of regulatory networks in eukaryotes.
authors.affiliation: Universidad de Chile, Facultad de Medicina, Instituto de Ciencias Biomédicas, Programa Biología Celular y Molecular, Independencia 1027, Santiago 7, Chile.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Rojas
authors.forename: Sandra
authors.initials: S
authors.lastname: Moreira-Ramos
authors.forename: Susanne
authors.initials: S
authors.lastname: Zock-Emmenthal
authors.forename: Fabiola
authors.initials: F
authors.lastname: Urbina
authors.forename: Juan
authors.initials: J
authors.lastname: Contreras-Levicoy
authors.forename: Norbert F
authors.initials: NF
authors.lastname: Käufer
authors.forename: Edio
authors.initials: E
authors.lastname: Maldonado
mesh_terms: D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D035463:Pol1 Transcription Initiation Complex Proteins / Q000235:genetics / Q000378:metabolism*; D012318:RNA Polymerase I / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000502:physiology*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal; D035463:Pol1 Transcription Initiation Complex Proteins; D029702:Schizosaccharomyces pombe Proteins; D012318:RNA Polymerase I