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Structure of human POT1 bound to telomeric single-stranded DNA provides a model for chromosome end-protection

Nature Structural & Molecular Biology volume 11, pages 1223–1229 (2004)Cite this article

Abstract

The POT1 (protection of telomeres 1) protein binds the single-stranded overhang at the ends of chromosomes in diverse eukaryotes. It is essential for chromosome end-protection in the fission yeast Schizosaccharomyces pombe, and it is involved in regulation of telomere length in human cells. Here, we report the crystal structure at a resolution of 1.73 Å of the N-terminal half of human POT1 (hPOT1) protein bound to a telomeric single-stranded DNA (ssDNA) decamer, TTAGGGTTAG, the minimum tight-binding sequence indicated by in vitro binding assays. The structure reveals that hPOT1 contains two oligonucleotide/ oligosaccharide-binding (OB) folds; the N-terminal OB fold binds the first six nucleotides, resembling the structure of the S. pombe Pot1pN–ssDNA complex, whereas the second OB fold binds and protects the 3′ end of the ssDNA. These results provide an atomic-resolution model for chromosome end-capping.

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Figure 1: Characterization of the interaction of hPOT1 with telomeric ssDNA.
Figure 2: Structure of the hPOT1V2–ssDNA complex.
Figure 3: Protein-ssDNA and ssDNA-ssDNA interactions in the hPOT1V2–ssDNA complex.
Figure 4: Telomeric DNA end-binding by hPOT1.
Figure 5: Model showing how hPOT1 could coat the entire 3′-end single-stranded overhang of a chromosome and inhibit telomerase activity.

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Acknowledgements

We thank L. Chen and D. Theobald (University of Colorado-Boulder) for insightful discussions and C. Ralston and G. McDermett (Advanced Light Source) for help in data collection. We thank K. Christensen and the tissue culture core facility of the University of Colorado Cancer Center for virus amplification and protein expression. This work was supported in part by a grant from the US National Institutes of Health. M.L. is an Agouron/Paul Sigler research fellow of the Helen Hay Whitney Foundation.

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  1. Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder, 80309-0215, Colorado, USA

    Ming Lei, Elaine R Podell & Thomas R Cech

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  2. Elaine R Podell
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Correspondence to Thomas R Cech.

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Supplementary information

Supplementary Fig. 1

Two versions of hPOT1 (V1 = full-length hPOT1, V2 = N-terminal DNA-binding region) have equivalent DNA-binding properties. (PDF 84 kb)

Supplementary Fig. 2

Adding a 5′ end nucleotide (C) rescues the ssDNA-binding activity of 9mer (TAGGGTTAG). (PDF 56 kb)

Supplementary Fig. 3

Extra 5′ end nucleotides do not interfere with the hPOT1-ssDNA interaction, whereas as extra 3′ end nucleotides weaken the interaction. (PDF 62 kb)

Supplementary Fig. 4

Protein-ssDNA interactions between G10 and its peripheral protein residues. (PDF 85 kb)

Supplementary Fig. 5

hPOT1 contains two OB folds. (PDF 429 kb)

Supplementary Fig. 6

Structure-based sequence alignment of the Pot1 proteins of several vertebrates (human, mouse, rat and chicken). (PDF 951 kb)

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Lei, M., Podell, E. & Cech, T. Structure of human POT1 bound to telomeric single-stranded DNA provides a model for chromosome end-protection. Nat Struct Mol Biol 11, 1223–1229 (2004). https://doi.org/10.1038/nsmb867

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