Abstract
The heterodimeric Ku complex affects telomere structure in diverse organisms. We report here that in the absence of Ku, the catalytic subunit of telomerase, Est2p, was not telomere-associated in G1 phase, and its association in late S phase was decreased. The telomere association of Est1p, a telomerase component that binds telomeres only in late S phase, was also reduced in the absence of Ku. The effects of Ku on telomerase binding require a 48-nucleotide (nt) stem-loop region of TLC1 telomerase RNA. Ku interacts with TLC1 RNA via this 48-nt region throughout the cell cycle, but this interaction was reduced after telomere replication. These data support a model in which Ku recruits telomerase to telomeres in G1 phase when telomerase is inactive and promotes telomerase-mediated telomere lengthening in late S phase.
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Acknowledgements
We thank S. Dunaway, L. Goudsouzian, A. Ivessa, M. Sabourin, and L. Vega for critical reading of the manuscript. We thank A. Chan for technical assistance and D. Gottschling and A. Stellwagen for strains. This work was supported by US National Institutes of Health (NIH) grant GM43265. T.S.F. is a Leukemia and Lymphoma Society Research Fellow. A.K.P.T was supported in part by a postdoctoral fellowship from the Susan G. Komen Breast Cancer Foundation and also NIH grant T32 CA09528.
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Supplementary information
Supplementary Fig. 1
Telomere phenotypes of Myc-tagged yKu80p strain. (PDF 321 kb)
Supplementary Fig. 2
Est2p telomere association in G1 and late S phase is also affected in yku80-135i cells. (PDF 279 kb)
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Fisher, T., Taggart, A. & Zakian, V. Cell cycle-dependent regulation of yeast telomerase by Ku. Nat Struct Mol Biol 11, 1198–1205 (2004). https://doi.org/10.1038/nsmb854
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DOI: https://doi.org/10.1038/nsmb854
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