Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL 61801, USA.
J Mol Biol. 2010 Apr 2;397(3):789-98. doi: 10.1016/j.jmb.2010.01.071. Epub 2010 Feb 6.
We survey the two-state to downhill folding transition by examining 20 lambda(6-85)* mutants that cover a wide range of stabilities and folding rates. We investigated four new lambda(6-85)* mutants designed to fold especially rapidly. Two were engineered using the core remodeling of Lim and Sauer, and two were engineered using Ferreiro et al.'s frustratometer. These proteins have probe-dependent melting temperatures as high as 80 degrees C and exhibit a fast molecular phase with the characteristic temperature dependence of the amplitude expected for downhill folding. The survey reveals a correlation between melting temperature and downhill folding previously observed for the beta-sheet protein WW domain. A simple model explains this correlation and predicts the melting temperature at which downhill folding becomes possible. An X-ray crystal structure with a 1.64-A resolution of a fast-folding mutant fragment shows regions of enhanced rigidity compared to the full wild-type protein.
我们通过研究 20 个覆盖广泛稳定性和折叠速率范围的 lambda(6-85)*突变体来调查二态到下坡折叠的转变。我们研究了四个新的 lambda(6-85)*突变体，旨在特别快速折叠。两个是使用 Lim 和 Sauer 的核心重塑设计的，两个是使用 Ferreiro 等人的 frustratometer 设计的。这些蛋白质具有探针依赖性熔点高达 80°C，并且表现出快速分子相，其幅度的温度依赖性与预期的下坡折叠的幅度的温度依赖性一致。该调查揭示了先前在β-折叠蛋白 WW 结构域中观察到的融化温度与下坡折叠之间的相关性。一个简单的模型解释了这种相关性，并预测了下坡折叠成为可能的熔点。一个快速折叠突变体片段的分辨率为 1.64-A 的 X 射线晶体结构显示与完整的野生型蛋白质相比，增强的刚性区域。
