title: Cell cycle-dependent transcription factors control the expression of yeast telomerase RNA.
abstract: Telomerase is a specialized ribonucleoprotein that adds repeated DNA sequences to the ends of eukaryotic chromosomes to preserve genome integrity. Some secondary structure features of the telomerase RNA are very well conserved, and it serves as a central scaffold for the binding of associated proteins. The Saccharomyces cerevisiae telomerase RNA, TLC1, is found in very low copy number in the cell and is the limiting component of the known telomerase holoenzyme constituents. The reasons for this low abundance are unclear, but given that the RNA is very stable, transcriptional control mechanisms must be extremely important. Here we define the sequences forming the TLC1 promoter and identify the elements required for its low expression level, including enhancer and repressor elements. Within an enhancer element, we found consensus sites for Mbp1/Swi4 association, and chromatin immunoprecipitation (ChIP) assays confirmed the binding of Mbp1 and Swi4 to these sites of the TLC1 promoter. Furthermore, the enhancer element conferred cell cycle-dependent regulation to a reporter gene, and mutations in the Mbp1/Swi4 binding sites affected the levels of telomerase RNA and telomere length. Finally, ChIP experiments using a TLC1 RNA-binding protein as target showed cell cycle-dependent transcription of the TLC1 gene. These results indicate that the budding yeast TLC1 RNA is transcribed in a cell cycle-dependent fashion late in G1 and may be part of the S phase-regulated group of genes involved in DNA replication.
authors.affiliation: RNA Group, Department of Microbiology and Infectiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec J1E 4K8, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Dionne
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Larose
authors.forename: Alain T
authors.initials: AT
authors.lastname: Dandjinou
authors.forename: Sherif
authors.initials: S
authors.lastname: Abou Elela
authors.forename: Raymund J
authors.initials: RJ
authors.lastname: Wellinger
mesh_terms: D001665:Binding Sites; D002453:Cell Cycle; D047369:Chromatin Immunoprecipitation; D015825:Chromosomes, Fungal / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D009154:Mutation; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D059505:Telomere Homeostasis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C083209:MBP1 protein, S cerevisiae; D012331:RNA, Fungal; C062214:SWI4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D019098:Telomerase
keywords: DNA replication; cell cycle; ribonucleoprotein; telomerase; telomere