Mustafa Golam, Gyawali Prabesh, Taylor Jacob A, Maleki Parastoo, Nunez Marlon V, Guntrum Michael C, Shiekh Sajad, Balci Hamza
Department of Physics, Kent State University, Kent, OH, United States.
Front Mol Biosci. 2022 Aug 22;9:977113. doi: 10.3389/fmolb.2022.977113. eCollection 2022.
We present a collection of single molecule work on the i-motif structure formed by the human telomeric sequence. Even though it was largely ignored in earlier years of its discovery due to its modest stability and requirement for low pH levels (pH < 6.5), the i-motif has been attracting more attention recently as both a physiologically relevant structure and as a potent pH sensor. In this manuscript, we establish single molecule Förster resonance energy transfer (smFRET) as a tool to study the i-motif over a broad pH and ionic conditions. We demonstrate pH and salt dependence of i-motif formation under steady state conditions and illustrate the intermediate states visited during i-motif folding in real time at the single molecule level. We also show the prominence of intermediate folding states and reversible folding/unfolding transitions. We present an example of using the i-motif as an pH sensor and use this sensor to establish the time scale for the pH drop in a commonly used oxygen scavenging system.
我们展示了一系列关于由人类端粒序列形成的i-基序结构的单分子研究工作。尽管在其发现的早期，由于其稳定性一般且需要低pH水平（pH < 6.5），它在很大程度上被忽视了，但近年来，i-基序作为一种生理相关结构和一种强大的pH传感器，受到了越来越多的关注。在本论文中，我们建立了单分子荧光共振能量转移（smFRET）作为一种工具，用于在广泛的pH和离子条件下研究i-基序。我们展示了稳态条件下i-基序形成对pH和盐的依赖性，并在单分子水平实时说明了i-基序折叠过程中经历的中间状态。我们还展示了中间折叠状态的突出性以及可逆的折叠/去折叠转变。我们给出了一个将i-基序用作pH传感器的例子，并使用该传感器确定了常用的氧清除系统中pH下降的时间尺度。
