Department of Chemistry and Physics, Coastal Carolina University, Smith Science Center, Room 216, 109 Chanticleer Dr. East, Conway, SC 29526, USA.
Department of Biology, University of Nebraska, Kearney, Bruner Hall of Science, 2401 11th Ave, Kearney, NE 68849, USA.
J Inorg Biochem. 2017 Jun;171:90-99. doi: 10.1016/j.jinorgbio.2017.03.008. Epub 2017 Mar 28.
RNA is known to interact with Mg when assuming higher-ordered tertiary configurations. Structurally, when tRNA molecules interact with Mg, they consistently form a "L-shape" conformation each time they are synthesized. Therefore, if Mg can induce tertiary structure formation, then binding to alternative cations could produce alternative tertiary configurations. By utilizing circular dichroism and mobility gel-shift assays it was observed that tRNA structure can be altered when in the presence of different divalent cationic species. Formation of these alternative structural configurations was further validated by aminoacylating these tRNA structural anomalies with their native enzyme, which resulted in markedly different degrees of activity. Thus, it was confirmed that structural changes do occur when tRNA forms complexes with different cations. To better understand these structural changes, quantitative cation binding to tRNA was determined through titrations as well as ICP-OES analysis, which indicated that the metal ions can bind to the tRNA structure in specific and non-specific ways. Lastly, it was observed through stopped-flow kinetics that tRNA can associate/dissociate from different cations to varying degrees, thus forming cation-specific complexes at unique rates.
RNA 已知在形成高级三级结构时与 Mg 相互作用。从结构上看，当 tRNA 分子与 Mg 相互作用时，它们在每次合成时都会形成一致的“L 形”构象。因此，如果 Mg 可以诱导三级结构的形成，那么与替代的阳离子结合可能会产生替代的三级结构。通过利用圆二色性和迁移凝胶阻滞实验，观察到当存在不同的二价阳离子物种时，tRNA 结构可以被改变。这些替代结构构象的形成进一步通过用其天然酶酰化这些 tRNA 结构异常来验证，这导致了明显不同程度的活性。因此，当 tRNA 与不同的阳离子形成复合物时，确实会发生结构变化。为了更好地理解这些结构变化，通过滴定和 ICP-OES 分析确定了定量的阳离子与 tRNA 的结合，这表明金属离子可以以特定和非特定的方式结合到 tRNA 结构上。最后，通过停流动力学观察到 tRNA 可以与不同的阳离子以不同的程度缔合/解离，从而以独特的速率形成阳离子特异性复合物。
