Fisher Charles K, Zhang Qi, Stelzer Andrew, Al-Hashimi Hashim M
Department of Chemistry & Biophysics, The University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055, USA.
J Phys Chem B. 2008 Dec 25;112(51):16815-22. doi: 10.1021/jp806188j.
Nuclear magnetic resonance (NMR) residual dipolar couplings (RDCs) provide a unique opportunity for spatially characterizing complex motions in biomolecules with time scale sensitivity extending up to milliseconds. Up to five motionally averaged Wigner rotation elements, (D(0k)2(alphaalpha)), can be determined experimentally using RDCs measured in five linearly independent alignment conditions and applied to define motions of axially symmetric bond vectors. Here, we show that up to 25 motionally averaged Wigner rotation elements, (D(mk)2(alphabetagamma)), can be determined experimentally from multialignment RDCs and used to characterize rigid-body motions of chiral domains. The 25 (D(mk)2(alphabetagamma)) elements form a basis set that allows one to measure motions of a domain relative to an isotropic distribution of reference frames anchored on a second domain (and vice versa), thus expanding the 3D spatial resolution with which motions can be characterized. The 25 (D(mk)2(alphabetagamma)) elements can also be used to fit an ensemble consisting of up to eight equally or six unequally populated states. For more than two domains, changing the identity of the domain governing alignment allows access to new information regarding the correlated nature of the domain fluctuations. Example simulations are provided that validate the theoretical derivation and illustrate the high spatial resolution with which rigid-body domain motions can be characterized using multialignment and multireference RDCs. Our results further motivate the development of experimental approaches for both modulating alignment and anchoring it on specifically targeted domains.
核磁共振(NMR)残余偶极耦合(RDCs)为在时间尺度灵敏度高达毫秒的情况下对生物分子中的复杂运动进行空间表征提供了独特的机会。使用在五个线性独立排列条件下测量的RDCs,最多可以通过实验确定五个运动平均的维格纳旋转元素(D(0k)2(αα)),并用于定义轴对称键向量的运动。在这里,我们表明,最多可以从多排列RDCs中通过实验确定25个运动平均的维格纳旋转元素(D(mk)2(αβγ)),并用于表征手性结构域的刚体运动。这25个(D(mk)2(αβγ))元素构成了一个基集,使得人们能够测量一个结构域相对于锚定在第二个结构域上的参考系的各向同性分布的运动(反之亦然),从而扩展了能够表征运动的三维空间分辨率。这25个(D(mk)2(αβγ))元素还可以用于拟合由多达八个等数量或六个不等数量的状态组成的系综。对于两个以上的结构域,改变控制排列的结构域的身份可以获取有关结构域波动的相关性质的新信息。提供了示例模拟,验证了理论推导,并说明了使用多排列和多参考RDCs表征刚体结构域运动时的高空间分辨率。我们的结果进一步推动了用于调节排列并将其锚定在特定靶向结构域上的实验方法的发展。