Tippana Ramreddy, Xiao Weikun, Myong Sua
Bioengineering Department, University of Illinois, 1304 W. Springfield Ave., Urbana, IL 61801, USA.
Bioengineering Department, University of Illinois, 1304 W. Springfield Ave., Urbana, IL 61801, USA Biophysics and Computational Biology, 1110 W. Green St., Urbana, IL 61801, USA Institute for Genomic Biology, 1206 Gregory Drive, Urbana, IL 61801, USA Physics Frontier Center (Center of Physics for Living Cells), University of Illinois, 1110 W. Green St., Urbana, IL 61801, USA
Nucleic Acids Res. 2014 Jul;42(12):8106-14. doi: 10.1093/nar/gku464. Epub 2014 Jun 11.
The quadruplex forming G-rich sequences are unevenly distributed throughout the human genome. Their enrichment in oncogenic promoters and telomeres has generated interest in targeting G-quadruplex (GQ) for an anticancer therapy. Here, we present a quantitative analysis on the conformations and dynamics of GQ forming sequences measured by single molecule fluorescence. Additionally, we relate these properties to GQ targeting ligands and G4 resolvase 1 (G4R1) protein binding. Our result shows that both the loop (non-G components) length and sequence contribute to the conformation of the GQ. Real time single molecule traces reveal that the folding dynamics also depend on the loop composition. We demonstrate that GQ-stabilizing small molecules, N-methyl mesoporphyrin IX (NMM), its analog, NMP and the G4R1 protein bind selectively to the parallel GQ conformation. Our findings point to the complexity of GQ folding governed by the loop length and sequence and how the GQ conformation determines the small molecule and protein binding propensity.
形成四链体的富含鸟嘌呤序列在整个人类基因组中分布不均。它们在致癌启动子和端粒中的富集引发了人们对靶向G-四链体（GQ）进行抗癌治疗的兴趣。在此，我们对通过单分子荧光测量的GQ形成序列的构象和动力学进行了定量分析。此外，我们将这些特性与GQ靶向配体和G4解旋酶1（G4R1）蛋白结合联系起来。我们的结果表明，环（非G成分）的长度和序列都对GQ的构象有影响。实时单分子轨迹显示，折叠动力学也取决于环的组成。我们证明，GQ稳定小分子N-甲基中卟啉IX（NMM）及其类似物NMP以及G4R1蛋白选择性地结合到平行GQ构象上。我们的研究结果指出了由环长度和序列决定的GQ折叠的复杂性，以及GQ构象如何决定小分子和蛋白质的结合倾向。
