School of Chemical and Biomolecular Sciences, Southern Illinois University Carbondale, 1245 Lincoln Drive MC 4409, Carbondale, IL 62901, United States.
School of Chemical and Biomolecular Sciences, Southern Illinois University Carbondale, 1245 Lincoln Drive MC 4409, Carbondale, IL 62901, United States.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Feb 15;267(Pt 2):120596. doi: 10.1016/j.saa.2021.120596. Epub 2021 Nov 10.
Guanine-rich nucleic acid sequences have a tendency to form four-stranded non-canonical motifs known as G-quadruplexes. These motifs may adopt a wide range of structures characterized by size, strand orientation, guanine base conformation, and fold topology. Using three K-bound model systems, we show that vibrational coupling between guanine C6 = O and ring modes varies between parallel-stranded and antiparallel-stranded G-quadruplexes, and that such structures can be distinguished by comparison of the polarization dependences of cross-peaks in their two-dimensional infrared (2D IR) spectra. Combined with previously defined vibrational frequency trends, this analysis reveals key features of a 30-nucleotide unimolecular variant of the Bcl-2 proximal promoter that are consistent with its reported structure. This study shows that 2D IR spectroscopy is a convenient method for analyzing G-quadruplex structures that can be applied to complex sequences where traditional high-resolution methods are limited by solubility and disorder.
富含鸟嘌呤的核酸序列倾向于形成称为 G-四链体的四链非 canonical 基序。这些基序可以采用多种结构，其特征在于大小、链取向、鸟嘌呤碱基构象和折叠拓扑。使用三个 K 结合模型系统，我们表明，鸟嘌呤 C6=O 和环模式之间的振动耦合在平行链和反平行链 G-四链体之间有所不同，并且可以通过比较其二维红外（2D IR）光谱中交叉峰的偏振依赖性来区分这些结构。结合先前定义的振动频率趋势，该分析揭示了 Bcl-2 近端启动子的 30 个核苷酸单分子变体的关键特征，这些特征与其报道的结构一致。这项研究表明，2D IR 光谱是分析 G-四链体结构的一种便捷方法，可应用于传统高分辨率方法受溶解度和无序限制的复杂序列。
