Multivalent binding of nonnative substrate proteins by the chaperonin GroEL
Multivalent binding of nonnative substrate proteins by the chaperonin GroEL
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DOI：
10.1016/s0092-8674(00)80692-3
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发表时间：
2000-03-03
期刊：
影响因子：
64.5
通讯作者：
Horwich, AL
中科院分区：
文献类型：
--
作者：
Farr, GW;Furtak, K;Horwich, AL
伴侣蛋白GroEL通过暴露在顶端结构域内侧的疏水残基在开环的中心腔中结合非天然底物蛋白，然后在结合ATP和辅伴侣蛋白GroES后介导生产性折叠。非天然蛋白质是否与GroEL环的七个顶端结构域中的一个以上结合尚不清楚。我们已经解决了这一问题，使用环与野生型和结合缺陷的突变体顶端结构域的各种组合，使他们的生产作为单一的多肽。一个野生型的二元复合物的形成与两个严格的底物蛋白，苹果酸脱氢酶或Rubisco的程度，需要至少三个连续的结合熟练的顶端域。Rhodanese是一种不太严格的底物，只需要两个野生型结构域，并且对它们的排列不敏感。作为一个物理相关，多价结合的Rubisco直接观察到在氧化交联实验。
The chaperonin GroEL binds nonnative substrate protein in the central cavity of an open ring through exposed hydrophobic residues at the inside aspect of the apical domains and then mediates productive folding upon binding ATP and the cochaperonin GroES. Whether nonnative proteins bind to more than one of the seven apical domains of a GroEL ring is unknown. We have addressed this using rings with various combinations of wild-type and binding-defective mutant apical domains, enabled by their production as single polypeptides. A wild-type extent of binary complex formation with two stringent substrate proteins, malate dehydrogenase or Rubisco, required a minimum of three consecutive binding-proficient apical domains. Rhodanese, a less-stringent substrate, required only two wild-type domains and was insensitive to their arrangement. As a physical correlate, multivalent binding of Rubisco was directly observed in an oxidative cross-linking experiment.