A captured folding intermediate involved in dimerization and domain-swapping of GB1
A captured folding intermediate involved in dimerization and domain-swapping of GB1
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DOI：
10.1016/j.jmb.2004.04.069
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发表时间：
2004-07-09
影响因子：
5.6
通讯作者：
Gronenborn, AM
中科院分区：
文献类型：
--
作者：
Byeon, IJL;Louis, JM;Gronenborn, AM
链球菌蛋白G的免疫球蛋白结合域B1(GB1)是一种小分子(56个残基)、稳定的单结构域蛋白，是蛋白质折叠和设计领域应用最广泛的模型系统之一。最近测定的一个四重突变体(HS#124(F26A)，L5V/F30V/Y33F/A34F)的核磁共振结构表明，在低微摩尔蛋白浓度下，结构域交换的二聚体解离为部分折叠的单体物种。在这里，我们已经用核磁共振表征了这种单体，部分折叠的物种，并表明多肽链的很大一部分存在广泛的构象异质性。在微秒到毫秒的时间尺度上，单体系综内的构象之间的交换使得大多数主链酰胺的共振扩大到无法检测到。尽管有这些广泛的时间和空间波动，单体突变蛋白的整体结构类似于野生型GB1，而不是结构域交换的二聚体的单体单位。(C)2004爱思唯尔有限公司。保留所有权利。
Immunoglobulin binding domain B1 of streptococcal protein G (GB1), a small (56 residues), stable, single domain protein, is one of the most extensively used model systems in the area of protein folding and design. The recently determined NMR structure of a quadruple mutant (HS#124(F26A), L5V/F30V/Y33F/A34F) revealed a domain-swapped dimer that dissociated into a partially folded, monomeric species at low micromolar protein concentrations. Here, we have characterized this monomeric, partially folded species by NMR and show that extensive conformational heterogeneity for a substantial portion of the polypeptide chain exists. Exchange between the conformers within the monomer ensemble on the microsecond to millisecond timescale renders the majority of backbone amide resonances broadened beyond detection. Despite these extensive temporal and spatial fluctuations, the overall architecture of the monomeric mutant protein resembles that of wild-type GB1 and not the monomer unit of the domain-swapped dimer. (C) 2004 Elsevier Ltd. All rights reserved.