RPA-like proteins mediate yeast telomere function

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Cdc13, Stn1 and Ten1 are essential yeast proteins that both protect chromosome termini from unregulated resection and regulate telomere length. Cdc13, which localizes to telomeres through high-affinity binding to telomeric single-stranded DNA, has been extensively characterized, whereas the contribution(s) of the Cdc13-associated Stn1 and Ten1 proteins to telomere function have remained unclear. We show here that Stn1 and Ten1 are DNA-binding proteins with specificity for telomeric DNA substrates. Furthermore, Stn1 and Ten1 show similarities to Rpa2 and Rpa3, subunits of the heterotrimeric replication protein A (RPA) complex, which is the major single-stranded DNA–binding activity in eukaryotic cells. We propose that Cdc13, Stn1 and Ten1 function as a telomere-specific RPA-like complex. Identification of an RPA-like complex that is targeted to a specific region of the genome suggests that multiple RPA-like complexes have evolved, each making individual contributions to genomic stability.

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Figure 1: Stn1 is an OB fold–containing protein.
Figure 2: The yeast Stn1 protein binds with enhanced specificity to telomeric substrates.
Figure 3: Ten1 binds telomeric DNA sequence-specifically.
Figure 4: Rpa2 and Rpa3 interact weakly with telomeric substrates.
Figure 5: Stn1 and Ten1 form a subcomplex analogous to the Rpa2–Rpa3 subcomplex.


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We thank the Brill (Rutgers University), Elledge (Harvard Medical School) and Wold (University of Iowa) laboratories for gifts of strains and plasmids, D. Wuttke and M. Wold for scientific conversations and advice, and E. Ford for technical assistance. This research was supported by Department of Defense postdoctoral fellowship DAMD 17-02-1-0276 (to R.B.C.), by grant GM55867 from the US National Institutes of Health and by the Lebensfeld Foundation.

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Correspondence to Victoria Lundblad.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Relative binding of Stn1, Ten1 and Stn164-199. (PDF 423 kb)

Supplementary Fig. 2

Yeast two-hybrid analysis with Cdc13, Stn1 and Ten1. (PDF 211 kb)

Supplementary Fig. 3

Comparison of the domain structure of subunits of the RPA and Cdc13-Stn1-Ten1 complexes. (PDF 384 kb)

Supplementary Table 1

List of plasmids used in this work. (PDF 63 kb)

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Gao, H., Cervantes, R., Mandell, E. et al. RPA-like proteins mediate yeast telomere function. Nat Struct Mol Biol 14, 208–214 (2007) doi:10.1038/nsmb1205

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