Multiple roles of prolyl residues in structure and folding
Multiple roles of prolyl residues in structure and folding
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DOI：
10.1006/jmbi.2000.4002
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发表时间：
2000-08-18
影响因子：
5.6
通讯作者：
Gierasch, LM
中科院分区：
文献类型：
--
作者：
Eyles, SJ;Gierasch, LM
为了探索脯氨酸残基可能影响多肽骨架的构象选择的方式，我们已经表征了细胞视黄酸结合蛋白I（CRABP I）的Pro -> Ala突变体。虽然所有三个Xaa-Pro键在天然蛋白质中均为反式构象，并且每个突变体的平衡稳定性与亲本蛋白质的平衡稳定性相似，但每个突变体对折叠和展开动力学具有不同的影响。Pro 105的突变不改变CRABP I的折叠动力学，这表明含有该残基的柔性环在折叠过程中是被动的。相比之下，用Ala取代Pro 85消除了可观察到的缓慢折叠阶段，揭示了84-85肽键的正确构型是有效折叠的先决条件。用Ala取代Pro39产生的蛋白质折叠和展开更慢。去除由脯氨酸环施加的构象约束可能通过增加缩小构象系综的熵成本来提高过渡态势垒。此外，Pro -> Ala突变去除了对于有效折叠至天然状态重要的螺旋终止信号。(C)北京大学出版社.
To explore the ways that proline residues may influence the conformational options of a polypeptide backbone, we have characterized Pro --> Ala mutants of cellular retinoic acid-binding protein I (CRABP I). While all three Xaa-Pro bonds are in the irans conformation in the native protein and the equilibrium stability of each mutant is similar to that of the parent protein, each has distinct effects on folding and unfolding kinetics. The mutation of Pro105 does not alter the kinetics of folding of CRABP I, which indicates that the flexible loop containing this residue is passive in the folding process. By contrast, replacement of Pro85 by Ala abolishes the observable slow phase of folding, revealing that correct configuration of the 84-85 peptide bond is prerequisite to productive folding. Substitution of Pro39 by Ala yields a protein that folds and unfolds more slowly. Removal of the conformational constraint imposed by the proline ring likely raises the transition state barrier by increasing the entropic cost of narrowing the conformational ensemble. Additionally, the Pro --> Ala mutation removes a helix-termination signal that is important for efficient folding to the native state. (C) 2000 Academic Press.