Insights into POT1 structural dynamics revealed by cryo-EM

Telomeres are protein-DNA complexes that protect the ends of linear eukaryotic chromosomes. Mammalian telomeric DNA consists of 5'-(TTAGGG)n-3' double-stranded repeats, followed by up to several hundred bases of a 3' single-stranded G-rich overhang. The G-rich overhang is bound by the...

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Main Authors: Smith, Emmanuel W., Lattmann, Simon, Liu, Barry Zhehui, Ahsan, Bilal, Rhodes, Daniela
Other Authors: School of Biological Sciences
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Language:English
Published: 2022
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Online Access:https://hdl.handle.net/10356/163095
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spelling sg-ntu-dr.10356-1630952023-02-28T17:11:38Z Insights into POT1 structural dynamics revealed by cryo-EM Smith, Emmanuel W. Lattmann, Simon Liu, Barry Zhehui Ahsan, Bilal Rhodes, Daniela School of Biological Sciences NTU Institute of Structural Biology Science::Biological sciences Oligonucleotide Binding Affinity Telomeres are protein-DNA complexes that protect the ends of linear eukaryotic chromosomes. Mammalian telomeric DNA consists of 5'-(TTAGGG)n-3' double-stranded repeats, followed by up to several hundred bases of a 3' single-stranded G-rich overhang. The G-rich overhang is bound by the shelterin component POT1 which interacts with TPP1, the component involved in telomerase recruitment. A previously published crystal structure of the POT1 N-terminal half bound to the high affinity telomeric ligand 5'-TTAGGGTTAG-3' showed that the first six nucleotides, TTAGGG, are bound by the OB1 fold, while the adjacent OB2 binds the last four, TTAG. Here, we report two cryo-EM structures of full-length POT1 bound by the POT1-binding domain of TPP1. The structures differ in the relative orientation of the POT1 OB1 and OB2, suggesting that these two DNA-binding OB folds take up alternative conformations. Supporting DNA binding studies using telomeric ligands in which the OB1 and OB2 binding sites were spaced apart, show that POT1 binds with similar affinities to spaced or contiguous binding sites, suggesting plasticity in DNA binding and a role for the alternative conformations observed. A likely explanation is that the structural flexibility of POT1 enhances binding to the tandemly arranged telomeric repeats and hence increases telomere protection. Ministry of Education (MOE) Published version This research was supported by a Singapore Ministry of Education Academic Research Fund (AcRF) Tier 3 [MOE2012-T3-1- 001]. Funding for open access charge: Singapore Ministry of Education Academic Research. 2022-11-21T05:52:18Z 2022-11-21T05:52:18Z 2022 Journal Article Smith, E. W., Lattmann, S., Liu, B. Z., Ahsan, B. & Rhodes, D. (2022). Insights into POT1 structural dynamics revealed by cryo-EM. PloS One, 17(2), e0264073-. https://dx.doi.org/10.1371/journal.pone.0264073 1932-6203 https://hdl.handle.net/10356/163095 10.1371/journal.pone.0264073 35176105 2-s2.0-85124779804 2 17 e0264073 en MOE2012-T3-1- 001 PloS one © 2022 Smith et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Biological sciences
Oligonucleotide
Binding Affinity
spellingShingle Science::Biological sciences
Oligonucleotide
Binding Affinity
Smith, Emmanuel W.
Lattmann, Simon
Liu, Barry Zhehui
Ahsan, Bilal
Rhodes, Daniela
Insights into POT1 structural dynamics revealed by cryo-EM
description Telomeres are protein-DNA complexes that protect the ends of linear eukaryotic chromosomes. Mammalian telomeric DNA consists of 5'-(TTAGGG)n-3' double-stranded repeats, followed by up to several hundred bases of a 3' single-stranded G-rich overhang. The G-rich overhang is bound by the shelterin component POT1 which interacts with TPP1, the component involved in telomerase recruitment. A previously published crystal structure of the POT1 N-terminal half bound to the high affinity telomeric ligand 5'-TTAGGGTTAG-3' showed that the first six nucleotides, TTAGGG, are bound by the OB1 fold, while the adjacent OB2 binds the last four, TTAG. Here, we report two cryo-EM structures of full-length POT1 bound by the POT1-binding domain of TPP1. The structures differ in the relative orientation of the POT1 OB1 and OB2, suggesting that these two DNA-binding OB folds take up alternative conformations. Supporting DNA binding studies using telomeric ligands in which the OB1 and OB2 binding sites were spaced apart, show that POT1 binds with similar affinities to spaced or contiguous binding sites, suggesting plasticity in DNA binding and a role for the alternative conformations observed. A likely explanation is that the structural flexibility of POT1 enhances binding to the tandemly arranged telomeric repeats and hence increases telomere protection.
author2 School of Biological Sciences
author_facet School of Biological Sciences
Smith, Emmanuel W.
Lattmann, Simon
Liu, Barry Zhehui
Ahsan, Bilal
Rhodes, Daniela
format Article
author Smith, Emmanuel W.
Lattmann, Simon
Liu, Barry Zhehui
Ahsan, Bilal
Rhodes, Daniela
author_sort Smith, Emmanuel W.
title Insights into POT1 structural dynamics revealed by cryo-EM
title_short Insights into POT1 structural dynamics revealed by cryo-EM
title_full Insights into POT1 structural dynamics revealed by cryo-EM
title_fullStr Insights into POT1 structural dynamics revealed by cryo-EM
title_full_unstemmed Insights into POT1 structural dynamics revealed by cryo-EM
title_sort insights into pot1 structural dynamics revealed by cryo-em
publishDate 2022
url https://hdl.handle.net/10356/163095
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