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Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding

Ends of human chromosomes consist of the six nucleotide repeat d[pTTAGGG](n) known as telomeric DNA, which protects chromosomes. We have previously shown that the DHX36 gene product, G4 Resolvase 1 (G4R1), binds parallel G-quadruplex (G4) DNA with an unusually tight apparent K(d). Recent work associ...

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Autores principales: Smaldino, Philip J., Routh, Eric D., Kim, Jung H., Giri, Banabihari, Creacy, Steven D., Hantgan, Roy R., Akman, Steven A., Vaughn, James P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501837/
https://www.ncbi.nlm.nih.gov/pubmed/26172836
http://dx.doi.org/10.1371/journal.pone.0132668
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author Smaldino, Philip J.
Routh, Eric D.
Kim, Jung H.
Giri, Banabihari
Creacy, Steven D.
Hantgan, Roy R.
Akman, Steven A.
Vaughn, James P.
author_facet Smaldino, Philip J.
Routh, Eric D.
Kim, Jung H.
Giri, Banabihari
Creacy, Steven D.
Hantgan, Roy R.
Akman, Steven A.
Vaughn, James P.
author_sort Smaldino, Philip J.
collection PubMed
description Ends of human chromosomes consist of the six nucleotide repeat d[pTTAGGG](n) known as telomeric DNA, which protects chromosomes. We have previously shown that the DHX36 gene product, G4 Resolvase 1 (G4R1), binds parallel G-quadruplex (G4) DNA with an unusually tight apparent K(d). Recent work associates G4R1 with the telomerase holoenzyme, which may allow it to access telomeric G4-DNA. Here we show that G4R1 can tightly bind telomeric G4-DNA, and in the context of the telomeric sequence, we determine length, sequence, and structural requirements sufficient for tight G4R1 telomeric binding. Specifically, G4R1 binds telomeric DNA in the K(+)-induced “3+1” G4-topology with an apparent K(d) = 10 ±1.9 pM, a value similar as previously found for binding to unimolecular parallel G4-DNA. G4R1 binds to the Na(+)-induced “2+2” basket G4-structure formed by the same DNA sequence with an apparent K(d) = 71 ± 2.2 pM. While the minimal G4-structure is not sufficient for G4R1 binding, a 5’ G4-structure with a 3’ unstructured tail containing a guanine flanked by adenine(s) is sufficient for maximal binding. Mutations directed to disrupt G4-structure similarly disrupt G4R1 binding; secondary mutations that restore G4-structure also restore G4R1 binding. We present a model showing that a replication fork disrupting a T-loop could create a 5’ quadruplex with an opened 3’tail structure that is recognized by G4R1.
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spelling pubmed-45018372015-07-17 Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding Smaldino, Philip J. Routh, Eric D. Kim, Jung H. Giri, Banabihari Creacy, Steven D. Hantgan, Roy R. Akman, Steven A. Vaughn, James P. PLoS One Research Article Ends of human chromosomes consist of the six nucleotide repeat d[pTTAGGG](n) known as telomeric DNA, which protects chromosomes. We have previously shown that the DHX36 gene product, G4 Resolvase 1 (G4R1), binds parallel G-quadruplex (G4) DNA with an unusually tight apparent K(d). Recent work associates G4R1 with the telomerase holoenzyme, which may allow it to access telomeric G4-DNA. Here we show that G4R1 can tightly bind telomeric G4-DNA, and in the context of the telomeric sequence, we determine length, sequence, and structural requirements sufficient for tight G4R1 telomeric binding. Specifically, G4R1 binds telomeric DNA in the K(+)-induced “3+1” G4-topology with an apparent K(d) = 10 ±1.9 pM, a value similar as previously found for binding to unimolecular parallel G4-DNA. G4R1 binds to the Na(+)-induced “2+2” basket G4-structure formed by the same DNA sequence with an apparent K(d) = 71 ± 2.2 pM. While the minimal G4-structure is not sufficient for G4R1 binding, a 5’ G4-structure with a 3’ unstructured tail containing a guanine flanked by adenine(s) is sufficient for maximal binding. Mutations directed to disrupt G4-structure similarly disrupt G4R1 binding; secondary mutations that restore G4-structure also restore G4R1 binding. We present a model showing that a replication fork disrupting a T-loop could create a 5’ quadruplex with an opened 3’tail structure that is recognized by G4R1. Public Library of Science 2015-07-14 /pmc/articles/PMC4501837/ /pubmed/26172836 http://dx.doi.org/10.1371/journal.pone.0132668 Text en © 2015 Smaldino et al http://creativecommons.org/licenses/by/4.0/ 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 properly credited.
spellingShingle Research Article
Smaldino, Philip J.
Routh, Eric D.
Kim, Jung H.
Giri, Banabihari
Creacy, Steven D.
Hantgan, Roy R.
Akman, Steven A.
Vaughn, James P.
Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title_full Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title_fullStr Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title_full_unstemmed Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title_short Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3’-Tail Sequences Are Sufficient for Tight and Complete Binding
title_sort mutational dissection of telomeric dna binding requirements of g4 resolvase 1 shows that g4-structure and certain 3’-tail sequences are sufficient for tight and complete binding
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501837/
https://www.ncbi.nlm.nih.gov/pubmed/26172836
http://dx.doi.org/10.1371/journal.pone.0132668
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