Soss Sarah E, Flynn Peter F
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
Biochemistry. 2007 Dec 25;46(51):14979-86. doi: 10.1021/bi701254q. Epub 2007 Nov 29.
The kink-turn (K-turn) motif is recognized and bound by a family of proteins that act as nucleation factors for ribonucleoparticle assembly. The binding of various proteins to a conserved RNA structural motif known as the K-turn has been shown to be an important component of regulation in the ribosome, in the spliceosome, and in RNA modification. 15.5K is a prototypical example of a K-turn binding protein, which has been shown to bind the 5'-U4 stem-loop of the spliceosome and the box C/D motif. We describe the solution NMR structure of free 15.5K, as well as studies of conformational flexibility from 15N NMR relaxation and H/D exchange experiments. The protein appears well-structured aside from conformational fluctuation in alpha3. Flexibility in fast time scale motions and the observation of limited intermediate and slow motions further characterize the free protein and may suggest local contributions to recognition and binding.
扭结转角（K-turn）基序可被一类作为核糖核蛋白颗粒组装成核因子的蛋白质识别并结合。多种蛋白质与一种名为扭结转角的保守RNA结构基序的结合，已被证明是核糖体、剪接体和RNA修饰调控的重要组成部分。15.5K是扭结转角结合蛋白的典型例子，已证明它能结合剪接体的5'-U4茎环和C/D盒基序。我们描述了游离15.5K的溶液核磁共振结构，以及通过15N核磁共振弛豫和H/D交换实验对其构象灵活性的研究。除α3中的构象波动外，该蛋白质看起来结构良好。快速时间尺度运动的灵活性以及有限的中间和慢速运动的观察结果进一步表征了游离蛋白质，并可能暗示了对识别和结合的局部贡献。
