Taking a molecular motor for a spin: helicase mechanism studied by spin labeling and PELDOR.
Taking a molecular motor for a spin: helicase mechanism studied by spin labeling and PELDOR.
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DOI：
10.1093/nar/gkv1373
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发表时间：
2016-01-29
影响因子：
14.9
通讯作者：
White MF
中科院分区：
文献类型：
--
作者：
Constantinescu-Aruxandei D;Petrovic-Stojanovska B;Schiemann O;Naismith JH;White MF
解旋酶功能中心的复杂分子运动长期以来一直吸引着人们的注意。蛋白质结晶学为这些动态构象变化提供了变革性的见解，然而关于催化循环中解旋酶配置的真实性质的重要问题仍然存在。用脉冲EPR(PELDOR或DEER)测量溶液中的结构域间距离，我们研究了两个有代表性的解旋酶：超家族1的PcrA和超家族2的XPD。数据表明，PcrA是一个动态结构，结构域移动与特定的功能状态相关，证实和扩展了从晶体结构和其他技术获得的信息。相反，XPD被证明是一种刚性蛋白质，几乎没有由于核苷酸或DNA结合而导致的构象变化，这可以用静态晶体结构很好地描述。我们的结果突出了PELDOR对结晶学的补充性质，以及它在理解与解旋酶功能相关的构象变化方面的精确度。
The complex molecular motions central to the functions of helicases have long attracted attention. Protein crystallography has provided transformative insights into these dynamic conformational changes, however important questions about the true nature of helicase configurations during the catalytic cycle remain. Using pulsed EPR (PELDOR or DEER) to measure interdomain distances in solution, we have examined two representative helicases: PcrA from superfamily 1 and XPD from superfamily 2. The data show that PcrA is a dynamic structure with domain movements that correlate with particular functional states, confirming and extending the information gleaned from crystal structures and other techniques. XPD in contrast is shown to be a rigid protein with almost no conformational changes resulting from nucleotide or DNA binding, which is well described by static crystal structures. Our results highlight the complimentary nature of PELDOR to crystallography and the power of its precision in understanding the conformational changes relevant to helicase function.