College of Biological Science and Medical Engineering, Donghua University, Shanghai 201620, China.
National Center for Protein Science Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, China.
Int J Mol Sci. 2024 Oct 20;25(20):11288. doi: 10.3390/ijms252011288.
Tandem SAM-II/SAM-V riboswitch belongs to a class of riboswitches found in the marine bacterium ' Pelagibacter ubique'. Previous studies have demonstrated that these riboswitches have the potential for digital modulation of gene expression at both the transcriptional and translational levels. In this study, we investigate the conformational changes in the tandem SAM-II/SAM-V riboswitch binding to S-adenosylmethionine (SAM) using selective 2'-hydroxyl acylation analyzed by the primer extension (SHAPE) assay, small-angle X-ray scattering (SAXS), and oligos depressing probing. Our findings reveal that the linker between SAM-II/SAM-V aptamers blocks the SAM response of the SAM-II domain. This result proposes a new mechanism for gene expression regulation, where the ligand-binding functions of tandem riboswitches can be selectively masked or released through a linker.
串联 SAM-II/SAM-V 核糖开关属于在海洋细菌“Pelagibacter ubique”中发现的一类核糖开关。先前的研究表明，这些核糖开关具有在转录和翻译水平上对基因表达进行数字调制的潜力。在这项研究中，我们使用选择性 2'-羟基酰化分析的引物延伸 (SHAPE) 测定、小角度 X 射线散射 (SAXS) 和寡核苷酸抑制探测来研究串联 SAM-II/SAM-V 核糖开关与 S-腺苷甲硫氨酸 (SAM) 结合时的构象变化。我们的研究结果表明，SAM-II/SAM-V 适体之间的连接物阻止了 SAM-II 结构域对 SAM 的响应。这一结果提出了一种新的基因表达调控机制，其中串联核糖开关的配体结合功能可以通过连接物选择性地屏蔽或释放。
