Characterizing the unfolding activation barrier of c-MYC G-quadruplex by temperature-dependent single-molecule force spectroscopy

IF 3.7 3区生物学 Q2 BIOPHYSICS

Biophysical journal Pub Date : 2026-10-20 DOI:10.1016/j.bpj.2026.10.015

Yingxian Qian,Yashuo Zhang,Hui Peng,Qun Luo,Huijuan You

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引用次数: 0

Abstract

Parallel-stranded G-quadruplexes (G4s) exhibit remarkable kinetic stability. However, it remains elusive whether this kinetic stability arises from an intrinsically high activation energy Ea or a constrained transition pathway. Here, we integrated an objective-based heating system with single-molecule magnetic tweezers to quantify the unfolding dynamics of c-MYC promoter G4s (MYC2345) from 16°C to 51°C. As the temperature increased, the peak unfolding force decreased from 58 ± 4 pN to 40 ± 4 pN, while the unfolding rate ku increased from (4.6 ± 0.1) × 10-8 s-1 to (1.4 ± 0.1) × 10-5 s-1. Arrhenius analysis yielded a moderate unfolding activation energy of 137 ± 19 kJ·mol-1 (∼55 kBT). Notably, this Arrhenius slope is markedly shallower than that of duplex DNA, demonstrating that G4 unfolding is less sensitive to thermal fluctuation than duplex melting. The kinetic stability of the c-MYC G4 is mainly due to the small transition distance rather than a high enthalpic barrier. Furthermore, the folding rate kf of G4 exhibits low temperature sensitivity, increasing 1.5-fold between 23°C and 37°C, suggesting that the folding kinetics are dominated by the entropic barrier. Our results provide a direct quantitative measurement of G4 energy landscapes.

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用温度依赖单分子力谱表征c-MYC g -四联体展开激活势垒

平行链g -四联体（G4s）具有显著的动力学稳定性。然而，这种动力学稳定性是由本质上的高活化能Ea还是受约束的过渡途径引起的，仍然是难以捉摸的。在这里，我们将基于物镜的加热系统与单分子磁镊子集成在一起，量化了C - myc启动子G4s （MYC2345）在16°C至51°C之间的展开动力学。随着温度的升高，展开力峰值由58±4 pN减小至40±4 pN，展开速率ku由（4.6±0.1）× 10-8 s-1增大至（1.4±0.1）× 10-5 s-1。阿伦尼乌斯分析得出了中等的展开活化能为137±19 kJ·mol-1 （~ 55 kBT）。值得注意的是，这个Arrhenius斜率明显比双链DNA的斜率浅，这表明G4展开对热波动的敏感性低于双链融化。c-MYC G4的动力学稳定性主要是由于小的跃迁距离而不是高的焓垒。此外，G4的折叠速率kf在23 ~ 37℃之间表现出较低的温度敏感性，增加了1.5倍，表明其折叠动力学受熵势垒控制。我们的结果提供了G4能源景观的直接定量测量。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Biophysical journal 生物-生物物理

CiteScore

6.10

自引率

5.90%

发文量

3090

审稿时长

2 months

期刊介绍： BJ publishes original articles, letters, and perspectives on important problems in modern biophysics. The papers should be written so as to be of interest to a broad community of biophysicists. BJ welcomes experimental studies that employ quantitative physical approaches for the study of biological systems, including or spanning scales from molecule to whole organism. Experimental studies of a purely descriptive or phenomenological nature, with no theoretical or mechanistic underpinning, are not appropriate for publication in BJ. Theoretical studies should offer new insights into the understanding ofexperimental results or suggest new experimentally testable hypotheses. Articles reporting significant methodological or technological advances, which have potential to open new areas of biophysical investigation, are also suitable for publication in BJ. Papers describing improvements in accuracy or speed of existing methods or extra detail within methods described previously are not suitable for BJ.