High Mechanical Stability and Slow Unfolding Rates Are Prevalent in Parallel-Stranded DNA G‑Quadruplexes

Guanine-rich repeat sequences are known to adopt diverse G-quadruplex (G4) topologies. Determining the unfolding rates of individual G4 species is challenging due to the coexistence of multiple G4 conformations in a solution. Here, using single-molecule magnetic tweezers, we systematically measured...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2020-10, Vol.11 (19), p.7966-7971
Main Authors: Cheng, Yuanlei, Zhang, Yashuo, Gong, Zhou, Zhang, Xinghua, Li, Yutong, Shi, Xiangqian, Pei, Yufeng, You, Huijuan
Format: Article
Language:English
Subjects:
Base Sequence
DNA - chemistry
G-Quadruplexes
Guanine - chemistry
Kinetics
Models, Molecular
Nucleic Acid Conformation
Physical Insights into Chemistry, Catalysis, and Interfaces
Promoter Regions, Genetic
Thymine - chemistry
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Summary:Guanine-rich repeat sequences are known to adopt diverse G-quadruplex (G4) topologies. Determining the unfolding rates of individual G4 species is challenging due to the coexistence of multiple G4 conformations in a solution. Here, using single-molecule magnetic tweezers, we systematically measured the unfolding force distributions of 4 oncogene promoter G4s, 12 model sequences with two 1-nucleotide (nt) thymine loops that predominantly adopt parallel-stranded G4 structures, and 6 sequences forming multiple G4 structures. All parallel-stranded G4s reveal an unfolding force peak at 40–60 pN, which is associated with extremely slow unfolding rates on the order of 10–5–10–7 s–1. In contrast, nonparallel G4s and partially folded intermediate states reveal an unfolding force peak
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.0c02229