Mustafa Golam, Shiekh Sajad, Alfehaid Janan, Kodikara Sineth G, Balci Hamza
Department of Physics, Kent State University, Kent, Ohio 44242, United States.
Biomacromolecules. 2025 Jul 14;26(7):4380-4386. doi: 10.1021/acs.biomac.5c00360. Epub 2025 Jun 13.
Molecular crowding─a defining feature of the cellular environment─affects folding kinetics, conformation, and stability of G-quadruplex (GQ) structures. However, its influence on the overall architecture and accessibility of telomeric overhangs containing multiple GQs remains largely unexplored. In this study, we employed single-molecule FRET and FRET-PAINT to address this question. We examined the accessibility of telomeric overhangs, capable of forming 1-6 GQs, to a short complementary peptide nucleic acid (PNA) imager probe in the presence of 200 and 6000 Da polyethylene glycol (PEG) molecules (PEG-200 and PEG-6000). We observed a progressive compaction and architectural condensation of the overhang as PEG concentration increased. At 30% concentration, this compaction was accompanied by approximately 3-fold and 8-fold reduction in probe accessibility in PEG-200 and PEG-6000, respectively. These findings offer new insights into how the crowded cellular environment may compact telomeric overhangs and modulate their structural and functional properties.
分子拥挤——细胞环境的一个决定性特征——会影响G-四链体（GQ）结构的折叠动力学、构象和稳定性。然而，其对包含多个GQ的端粒悬突的整体结构和可及性的影响在很大程度上仍未得到探索。在本研究中，我们采用单分子荧光共振能量转移（FRET）和FRET-点积累成像纳米技术（FRET-PAINT）来解决这个问题。我们在存在200和6000道尔顿聚乙二醇（PEG）分子（PEG-200和PEG-6000）的情况下，研究了能够形成1-6个GQ的端粒悬突对短互补肽核酸（PNA）成像探针的可及性。我们观察到随着PEG浓度增加，悬突逐渐压缩且结构凝聚。在30%的浓度下，这种压缩分别伴随着PEG-200和PEG-6000中探针可及性降低约3倍和8倍。这些发现为拥挤的细胞环境如何压缩端粒悬突并调节其结构和功能特性提供了新的见解。
