High-resolution x-ray crystal structures of the villin headpiece subdomain, an ultrafast folding protein
High-resolution x-ray crystal structures of the villin headpiece subdomain, an ultrafast folding protein
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DOI：
10.1073/pnas.0502495102
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发表时间：
2005-05-24
影响因子：
11.1
通讯作者：
Davies, DR
中科院分区：
文献类型：
--
作者：
Chiu, TK;Kubelka, J;Davies, DR
绒毛蛋白头片段（HP 35）的35个残基的亚结构域是一个小的超快折叠蛋白，正在通过实验，理论和模拟进行深入研究。我们已经解决了HP35及其最快的折叠突变体[K24正亮氨酸（nL）]的X射线结构原子分辨率和比较实验测量的折叠动力学，通过使用激光温度跳跃。在不同的空间群中的结构几乎彼此相同，但与先前解决的NMR结构显著不同。因此，X射线和NMR结构之间的差异可能不是由晶格接触或晶体/溶液差异引起的，而是反映了X射线结构的更高精度。的X-射线结构揭示了重要的细节包装的疏水核心和一些额外的功能，如交叉螺旋H键。X射线结构的比较表明，nL替代只产生局部扰动。因此，突变的小稳定性完全反映在折叠速率的增加中，这一发现表明蛋白质的该区域在过渡状态下的结构与折叠结构中的结构一样。因此，工程改造的目标是将亚结构域的折叠速率从nL突变体的约0.5 μ s（-1）增加到约3 μ s（-1）的估计理论速度极限。
The 35-residue subdomain of the villin headpiece (HP35) is a small ultrafast folding protein that is being intensely studied by experiments, theory, and simulations. We have solved the x-ray structures of HP35 and its fastest folding mutant [K24 norleucine (nL)] to atomic resolution and compared their experimentally measured folding kinetics by using laser temperature jump. The structures, which are in different space groups, are almost identical to each other but differ significantly from previously solved NMR structures. Hence, the differences between the x-ray and NMR structures are probably not caused by lattice contacts or crystal/solution differences, but reflect the higher accuracy of the x-ray structures. The x-ray structures reveal important details of packing of the hydrophobic core and some additional features, such as cross-helical H bonds. Comparison of the x-ray structures indicates that the nL substitution produces only local perturbations. Consequently, the finding that the small stabilization by the mutation is completely reflected in an increased folding rate suggests that this region of the protein is as structured in the transition state as in the folded structure. It is therefore a target for engineering to increase the folding rate of the subdomain from approximate to 0.5 mu s(-1) for the nL mutant to the estimated theoretical speed limit of approximate to 3 mu s(-1).