Cdk1 Regulates the Temporal Recruitment of Telomerase and Cdc13-Stn1-Ten1 Complex for Telomere Replication

Abstract

In budding yeast (Saccharomyces cerevisiae), the cell cycle-dependent telomere elongation by telomerase is controlled by the cyclin-dependent kinase 1 (Cdk1). The telomere length homeostasis is balanced between telomerase-unextendable and telomerase-extendable states that both require Cdc13. The recruitment of telomerase complex by Cdc13 promotes telomere elongation, while the formation of Cdc13-Stn1-Ten1 (CST) complex at the telomere blocks telomere elongation by telomerase. However, the cellular signaling that regulates the timing of the telomerase-extendable and telomerase-unextendable states is largely unknown. Phosphorylation of Cdc13 by Cdk1 promotes the interaction between Cdc13 and Est1 and hence telomere elongation. Here, we show that Cdk1 also phosphorylates Stn1 at threonine 223 and serine 250 both in vitro and in vivo, and these phosphorylation events are essential for the stability of the CST complexes at the telomeres. By controlling the timing of Cdc13 and Stn1 phosphorylations during cell cycle progression, Cdk1 regulates the temporal recruitment of telomerase complexes and CST complexes to the telomeres to facilitate telomere maintenance.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.01235-13.

ACKNOWLEDGMENTS

We thank Victoria Lundblad for providing the yeast two-hybrid plasmids pVL705 and pVL859, as well as the pJ694a yeast strain. We thank Constance I. Nugent for providing the yeast two-hybrid plasmids pCN124 (pAS1-TEN1) and pCN181 (pACT2-STN1). We thank Michel Charbonneau for providing the yeast two-hybrid plasmids pAS2-TEN1, pACT2-TEN1, pAS2-STN1, pACT2-STN1, pAS2-CDC13, and pACT2-CDC13. We thank XiaoLan Zhao for providing the yeast two-hybrid plasmids pOBD-CDC13 and pOAD-STN1. We thank Elizabeth H. Blackburn and Uttam Surana for critical reading of the manuscript.

This work was supported by grants from MOE tier 2 funding to S.L.