title: Hmo1 directs pre-initiation complex assembly to an appropriate site on its target gene promoters by masking a nucleosome-free region.
abstract: Saccharomyces cerevisiae Hmo1 binds to the promoters of ∼ 70% of ribosomal protein genes (RPGs) at high occupancy, but is observed at lower occupancy on the remaining RPG promoters. In Δhmo1 cells, the transcription start site (TSS) of the Hmo1-enriched RPS5 promoter shifted upstream, while the TSS of the Hmo1-limited RPL10 promoter did not shift. Analyses of chimeric RPS5/RPL10 promoters revealed a region between the RPS5 upstream activating sequence (UAS) and core promoter, termed the intervening region (IVR), responsible for strong Hmo1 binding and an upstream TSS shift in Δhmo1 cells. Chromatin immunoprecipitation analyses showed that the RPS5-IVR resides within a nucleosome-free region and that pre-initiation complex (PIC) assembly occurs at a site between the IVR and a nucleosome overlapping the TSS (+1 nucleosome). The PIC assembly site was shifted upstream in Δhmo1 cells on this promoter, indicating that Hmo1 normally masks the RPS5-IVR to prevent PIC assembly at inappropriate site(s). This novel mechanism ensures accurate transcriptional initiation by delineating the 5'- and 3'-boundaries of the PIC assembly zone.
authors.affiliation: Division of Molecular and Cellular Biology, Graduate School of Nanobioscience, Yokohama City University, Yokohama 230-0045, Japan. k4kasaha@nodai.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Kasahara
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Ohyama
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kokubo
mesh_terms: D017353:Gene Deletion; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019473:Transcription Factors, TFII / Q000235:genetics; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: C103154:HMO1 protein, S cerevisiae; D006609:High Mobility Group Proteins; D009707:Nucleosomes; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D019473:Transcription Factors, TFII; C030831:ribosomal protein S5; D012319:RNA Polymerase II; C511736:RPB1 protein, S cerevisiae; C509257:Rpb9 protein, S cerevisiae; C056604:transcription factor TFIIF