Mobility of individual 5-fluorouridine residues in 5-fluorouracil-substituted Escherichia coli valine transfer RNA. A 19F nuclear magnetic resonance relaxation study.
Mobility of individual 5-fluorouridine residues in 5-fluorouracil-substituted Escherichia coli valine transfer RNA. A 19F nuclear magnetic resonance relaxation study.
复制标题
5-氟尿嘧啶取代的大肠杆菌缬氨酸转移 RNA 中单个 5-氟尿苷残基的迁移率。
DOI：
10.1016/0022-2836(87)90564-x
复制
发表时间：
1987
影响因子：
5.6
通讯作者：
Horowitz,J
中科院分区：
文献类型：
--
作者：
Hardin,CC;Horowitz,J
19 F核磁共振（n.m.r.）测定了5-氟尿嘧啶取代的大肠杆菌RNA 1Val的弛豫参数，并用几种分子运动模型来表征单个5-氟尿苷（FUrd）残基的内部运动。测量的弛豫参数包括282 MHz处的自旋-晶格（T1）弛豫时间、282 MHz处的19 F1 H NOE以及根据338 MHz、282 MHz和84 MHz处的线宽数据估计的自旋-自旋（T2）弛豫时间。偶极和化学位移各向异性贡献的19 F弛豫参数确定从场依赖性的T2。结果表明，在282和338 MHz的19 F线宽的大的化学位移各向异性的贡献。化学位移各向异性弛豫数据的分析表明，相对于整体翻滚的大分子，可以忽略不计的扭转运动发生在19 F-标记的tRNA 1Val的FUrd残基的糖苷键，与碱基-碱基氢键和/或堆积相互作用的维护在分子中的所有氟尿嘧啶残基一致。偶极弛豫数据进行了分析，使用“两态跳跃”和“扩散锥”的形式主义。运动幅度（θ）被解释为是由于氟化核苷的核糖环内的伪旋转波动。假设相关时间（τi，2）为1.6 ns，这些振幅的范围约为30 °至60 °。通过使用可用的19 F n.m.r.根据5-氟尿嘧啶取代的tRNA 1Val中14个FUrd残基的分配数据，这些运动幅度可以与残基的环境结构域直接相关。位于三级结构域和螺旋结构域的残基显示出比位于环中的残基（θ = 45 °至60 °）明显更少的运动（θ = 30 °至35 °）。残留物的流动性和溶剂暴露之间的相关性也被证明。特定残基的内部运动的幅度同意相当好的与来自酵母tRNAPhe的X-射线衍射和分子动力学数据。
19F nuclear magnetic resonance (n.m.r.) relaxation parameters of 5-fluorouracil-substitutedEscherichia colitRNA1Valwere measured and used to characterize the internal mobility of individual 5-fluorouridine (FUrd) residues in terms of several models of molecular motion. Measured relaxation parameters include the spin-lattice (T1) relaxation time at 282 MHz, the19F1H NOE at 282 MHz, and the spin-spin (T2) relaxation time, estimated from linewidth data at 338 MHz, 282 MHz and 84 MHz. Dipolar and chemical shift anisotropy contributions to the19F relaxation parameters were determined from the field-dependence ofT2. The results demonstrate a large chemical shift anisotropy contribution to the19F linewidths at 282 and 338 MHz. Analysis of chemical shift anisotropy relaxation data shows that, relative to overall tumbling of the macromolecule, negligible torsional motion occurs about the glycosidic bond of FUrd residues in19F-labeled tRNA1Val, consistent with the maintenance of base-base hydrogen-bond and/or stacking interactions at all fluorouracil residues in the molecule. The dipolar relaxation data are analyzed by using the “two-state jump” and “diffusion in a cone” formalisms. Motional amplitudes (θ) are interpreted as being due to pseudorotational fluctuations within the ribose ring of the fluorinated nucleoside. These amplitudes range from approximately 30 ° to 60 °, assuming a correlation time (τi,2) of 1.6 ns. By using available19F n.m.r. assignment data for the 14 FUrd residues in 5-fluorouracil-substituted tRNA1Val, these motional amplitudes can be correlated directly with the environmental domain of the residue. Residues located in tertiary and helical structural domains show markedly less motion (θ ∼- 30 to 35 °) than residues located in loops (θ ∼- 45 to 60 °). A correlation between residue mobility and solvent exposure is also demonstrated. The amplitudes of internal motion for specific residues agree quite well with those derived from X-ray diffraction and molecular dynamics data for yeast tRNAPhe.