title: Differential effects of chromatin and Gcn4 on the 50-fold range of expression among individual yeast Ty1 retrotransposons.
abstract: Approximately 30 copies of the Ty1 retrotransposon are present in the genome of Saccharomyces cerevisiae. Previous studies gave insights into the global regulation of Ty1 transcription but provided no information on the behavior of individual genomic elements. This work shows that the expression of 31 individual Ty1 elements in S288C varies over a 50-fold range. Their transcription is repressed by chromatin structures, which are antagonized by the Swi/Snf and SAGA chromatin-modifying complexes in highly expressed Ty1 elements. These elements carry five potential Gcn4 binding sites in their promoter regions that are mostly absent in weakly expressed Ty1 copies. Consistent with this observation, Gcn4 activates the transcription of highly expressed Ty1 elements only. One of the potential Gcn4 binding sites acts as an upstream activating sequence in vivo and interacts with Gcn4 in vitro. Since Gcn4 has been shown to interact with Swi/Snf and SAGA, we predict that Gcn4 activates Ty1 transcription by targeting these complexes to specific Ty1 promoters.
authors.affiliation: UPR 9073 du CNRS, Institut de Biologie Physico-Chimique, F-75005 Paris, France.
authors.forename: Antonin
authors.initials: A
authors.lastname: Morillon
authors.forename: Lionel
authors.initials: L
authors.lastname: Bénard
authors.forename: Mathias
authors.initials: M
authors.lastname: Springer
authors.forename: Pascale
authors.initials: P
authors.lastname: Lesage
mesh_terms: D000596:Amino Acids / Q000172:deficiency / Q000378:metabolism; D001665:Binding Sites; D002843:Chromatin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011494:Protein Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D000596:Amino Acids; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012333:RNA, Messenger; D018626:Retroelements; C078562:SWI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases