Open AccessHmo1 Is Required for TOR-Dependent Regulation of Ribosomal Protein Gene Transcription
Author(s) -
Axel Bernhard Berger,
Laurence Decourty,
Gwenaël Badis,
Ulf Nehrbass,
Alain Jacquier,
Olivier Gadal
Publication year - 2007
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.01102-07
Subject(s) - biology , ribosome biogenesis , transcription (linguistics) , promoter , rna polymerase iii , gene , microbiology and biotechnology , rna polymerase ii , ribosomal protein , ribosome , gene expression , regulation of gene expression , transcriptional regulation , genetics , rna , rna polymerase , linguistics , philosophy
Ribosome biogenesis requires equimolar amounts of four rRNAs and all 79 ribosomal proteins (RP). Coordinated regulation of rRNA and RP synthesis by eukaryotic RNA polymerases (Pol) I, III, and II is a key requirement for growth control. Using a novel global genetic approach, we showed that the absence of Hmo1 becomes lethal when combined with mutations of components of either the RNA Pol II or Pol I transcription machineries, of specific RP, or of the TOR pathway. Hmo1 directly interacts with both the region transcribed by Pol I and a subset of RP gene promoters. Down-regulation of Hmo1 expression affects RP gene expression. Upon TORC1 inhibition, Hmo1 dissociates from ribosomal DNA (rDNA) and some RP gene promoters simultaneously. Finally, in the absence of Hmo1, TOR-dependent repression of RP genes is alleviated. Therefore, we show here that Saccharomyces cerevisiae Hmo1 is directly involved in coordinating rDNA transcription by Pol I and RP gene expression by Pol II under the control of the TOR pathway.