Vandre CL, et al. (2008) The DNA End-Binding Protein Ku Regulates Silencing at the Internal HML and HMR Loci in Saccharomyces cerevisiae. Genetics 180(3):1407-18
Abstract: Heterochromatin resides near yeast telomeres, and at the cryptic mating type loci, HML and HMR, where it silences transcription of the alpha and a mating-type genes, respectively. Ku is a conserved DNA end-binding protein that binds telomeres and regulates silencing in yeast. The role of Ku in silencing is thought to be limited to telomeric silencing. Here, we tested whether Ku contributes to silencing at HML or HMR. Mutant analysis revealed that yKu70 and Sir1 act collectively to silence the mating-type genes at HML and HMR. In addition, loss of yKu70 function lead to expression of different reporter genes inserted at HMR. Quantitative chromatin-immunoprecipitation experiments revealed that yKu70 binds to HML and HMR and that binding of Ku to these internal loci is dependent on Sir4. The interaction between yKu70 and Sir4 was characterized further and found to be dependent on Sir2 but not Sir1, Sir3 or yKu80. These observations reveal that in addition to its ability to bind telomeric DNA ends and aid in the silencing of genes at telomeres Ku binds to internal silent loci via protein-protein interactions and contributes to the efficient silencing of these loci.
|Status: Published||Type: Journal Article||PubMed ID: 18791224|
Topics addressed in this paper
Number of different genes curated to this paper: 8
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