Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan.
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan.
Biosens Bioelectron. 2021 Apr 15;178:113030. doi: 10.1016/j.bios.2021.113030. Epub 2021 Jan 23.
G-quadruplex (G4) is a non-canonical structure that is formed in G-rich sequences of nucleic acids. G4s play important roles in vivo, such as telomere maintenance, transcription, and DNA replication. There are three typical topologies of G4: parallel, anti-parallel, and hybrid. In general, metal cations, such as potassium and sodium, stabilize G4s through coordination in the G-quartet. While G4s have some functions in vivo, there are many reports of developed applications that use G4s. As various conformations of G4s could form from one sequence depending on varying conditions, many researchers have developed G4-based sensors. Furthermore, G4 is a great scaffold of aptamers since many aptamers folded into G4s have also been reported. However, there are some challenges about its practical use due to the difference between practical sample conditions and experimental ones. G4 conformations are dramatically altered by the surrounding conditions, such as metal cations, pH, and crowding. Many studies have been conducted to characterize G4 conformations under various conditions, not only to use G4s in practical applications but also to reveal its function in vivo. In this review, we summarize recent studies that have investigated the effects of surrounding conditions (e.g., metal cations, pH, and crowding) on G4 conformations and the application of G4s mainly in biosensor fields, and in others.
四链体（G4）是一种在富含鸟嘌呤的核酸序列中形成的非经典结构。G4 在体内发挥着重要作用，如端粒维持、转录和 DNA 复制。G4 有三种典型的拓扑结构：平行、反平行和杂合。一般来说，金属阳离子，如钾和钠，通过在 G-四联体中的配位来稳定 G4。虽然 G4 在体内具有一些功能，但有许多关于开发应用的报道利用了 G4。由于一个序列可以根据不同的条件形成多种构象，因此许多研究人员已经开发了基于 G4 的传感器。此外，G4 是适配体的理想支架，因为许多折叠成 G4 的适配体也已经被报道。然而，由于实际样品条件与实验条件之间的差异，其实际应用仍存在一些挑战。G4 的构象会因周围环境（如金属阳离子、pH 值和拥挤程度）的变化而发生显著改变。许多研究已经对各种条件下的 G4 构象进行了表征，不仅为 G4 在实际应用中提供了依据，也为揭示其在体内的功能提供了依据。在这篇综述中，我们总结了最近的研究，这些研究调查了周围环境（如金属阳离子、pH 值和拥挤程度）对 G4 构象的影响，以及 G4 主要在生物传感器领域的应用，以及其他领域的应用。
