Cho Jae-Hyun, Sato Satoshi, Raleigh Daniel P
Graduate Program in Biochemistry and Structural Biology, State University of New York at Stony Brook, Stony Brook, NY 11794-5230, USA.
J Mol Biol. 2004 May 7;338(4):827-37. doi: 10.1016/j.jmb.2004.02.073.
Comparatively little is known about the role of non-native interactions in protein folding and their role in both folding and stability is controversial. We demonstrate that non-native electrostatic interactions involving specific residues in the denatured state can have a significant effect upon protein stability and can persist in the transition state for folding. Mutation of a single surface exposed residue, Lys12 to Met, in the N-terminal domain of the ribosomal protein L9 (NTL9), significantly increased the stability of the protein and led to faster folding. Structural and energetic studies of the wild-type and K12M mutant show that the 1.9 kcal mol(-1) increase in stability is not due to native state effects, but rather is caused by modulation of specific non-native electrostatic interactions in the denatured state. pH dependent stability measurements confirm that the increased stability of the K12M is due to the elimination of favorable non-native interactions in the denatured state. Kinetic studies show that the non-native electrostatic interactions involving K12 persist in the transition state. The analysis demonstrates that canonical Phi-values can arise from the disruption of non-native interactions as well as from the development of native interactions.
关于非天然相互作用在蛋白质折叠中的作用，人们了解得相对较少，而且它们在折叠和稳定性方面的作用存在争议。我们证明，涉及变性状态下特定残基的非天然静电相互作用会对蛋白质稳定性产生显著影响，并且在折叠的过渡态中依然存在。核糖体蛋白L9（NTL9）N端结构域中一个暴露于表面的单个残基Lys12突变为Met，显著提高了该蛋白质的稳定性并导致更快的折叠。对野生型和K12M突变体的结构和能量研究表明，稳定性增加1.9千卡/摩尔（-1）并非由于天然态效应，而是由变性状态下特定非天然静电相互作用的调节引起的。pH依赖性稳定性测量证实，K12M稳定性的增加是由于消除了变性状态下有利的非天然相互作用。动力学研究表明，涉及K12的非天然静电相互作用在过渡态中持续存在。分析表明，标准Phi值可能源于非天然相互作用的破坏以及天然相互作用的形成。
