The chaperonin GroEL binds a polypeptide in an alpha-helical conformation.
The chaperonin GroEL binds a polypeptide in an alpha-helical conformation.
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DOI：
10.1021/bi00244a001
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发表时间：
1991-07
期刊：
影响因子：
2.9
通讯作者：
S. Landry;L. Gierasch
中科院分区：
文献类型：
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作者：
S. Landry;L. Gierasch
伴侣蛋白在体内促进新生多肽的折叠和组装，并在体外防止重折叠试验中的聚集。一个特定的伴侣作用于许多不同的蛋白质。因此，伴侣蛋白必须识别存在于不完全折叠的多肽链中的特征，而不是严格依赖于初级结构信息。我们使用转移核Overhauser效应来证明大肠杆菌伴侣蛋白GroEL与罗丹斯蛋白n端α -螺旋相对应的肽结合，罗丹斯蛋白是一种线粒体蛋白，通过添加GroEL、GroES和ATP可以促进其体外再折叠。此外，肽在水溶液中游离时是无结构的，与GroEL结合时采用α -螺旋构象。对肽进行修饰以减少其固有的螺旋结构倾向，降低了其对GroEL的亲和力，但尽管如此，它可以结合并在结合时呈现螺旋构象。我们提出GroEL与不完全折叠链中的序列相互作用，这些序列有可能采用两亲型α -螺旋，并且伴侣蛋白结合位点促进了螺旋的形成。
Chaperones facilitate folding and assembly of nascent polypeptides in vivo and prevent aggregation in refolding assays in vitro. A given chaperone acts on a number of different proteins. Thus, chaperones must recognize features present in incompletely folded polypeptide chains and not strictly dependent on primary structural information. We have used transferred nuclear Overhauser effects to demonstrate that the Escherichia coli chaperonin GroEL binds to a peptide corresponding to the N-terminal alpha-helix in rhodanese, a mitochondrial protein whose in vitro refolding is facilitated by addition of GroEL, GroES, and ATP. Furthermore, the peptide, which is unstructured when free in aqueous solution, adopts an alpha-helical conformation upon binding to GroEL. Modification of the peptide to reduce its intrinsic propensity to take up alpha-helical structure lowered its affinity for GroEL, but, nonetheless, it could be bound and took up a helical conformation when bound. We propose that GroEL interacts with sequences in an incompletely folded chain that have the potential to adopt an amphipathic alpha-helix and that the chaperonin binding site promotes formation of a helix.