Group II archaeal chaperonin recognition of partially folded human γD-crystallin mutants.
Group II archaeal chaperonin recognition of partially folded human γD-crystallin mutants.
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第二组古菌伴侣蛋白识别部分折叠的人类γD-晶状体蛋白突变体。
DOI：
10.1002/pro.2452
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Knee,KellyM
中科院分区：
文献类型：
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作者：
Sergeeva,OksanaA;Yang,Jingkun;King,JonathanA;Knee,KellyM
在部分折叠的中间物中，允许II组伴侣蛋白区分部分折叠和原始状态的特征仍然不清楚。来自毛利帕氏甲烷球菌（methanococcus Mauripaludis）的古细菌II族伴侣蛋白（Mm‐Cpn）协助它们的体外折叠充分表征的β -片状晶状体蛋白人γ - d -晶体蛋白（h - γD‐Crys）。希腊键构象的结构域界面和埋藏核包括侧链，可能暴露在部分折叠的中间物中。我们试图评估是否隐藏在天然状态下的特定特征，但不存在于天然蛋白表面，可能作为识别信号。测试的特征是(a)配对芳香侧链，(b) h - γ - d - Crys重复结构域之间的界面侧链，以及(c)取代后导致先天性白内障的埋藏核心侧链。在变性剂稀释后，我们测试了Mm - Cpn对这些h - γ d - Crys突变体聚集的抑制作用。Mm‐Cpn能够抑制这三类突变体的通路外聚集，这表明被掩埋的残基不是识别信号。事实上，Mm‐Cpn比（野生型）WT更好地识别了h - γ d‐Crys突变体，并将大多数突变体h - γ d‐Crys重新折叠到WT h - γ d‐Crys的两倍水平。这大概代表了突变蛋白部分折叠的中间体的数量增加或寿命延长。结果表明，Mm‐Cpn不能识别hγ - d - Crys被测的配对芳烃、暴露的结构域界面或不稳定的核，而是识别部分折叠的β -片构象的其他特征，这些特征在hγ - d - Crys的天然状态中是不存在的或无法接近的。
The features in partially folded intermediates that allow the group II chaperonins to distinguish partially folded from native states remain unclear. The archaeal group II chaperonin fromMethanococcus Mauripaludis(Mm‐Cpn) assists thein vitrorefolding of the well‐characterized β‐sheet lens protein human γD‐crystallin (HγD‐Crys). The domain interface and buried cores of this Greek key conformation include side chains, which might be exposed in partially folded intermediates. We sought to assess whether particular features buried in the native state, but absent from the native protein surface, might serve as recognition signals. The features tested were (a) paired aromatic side chains, (b) side chains in the interface between the duplicated domains of HγD‐Crys, and (c) side chains in the buried core which result in congenital cataract when substituted. We tested the Mm‐Cpn suppression of aggregation of these HγD‐Crys mutants upon dilution out of denaturant. Mm‐Cpn was capable of suppressing the off‐pathway aggregation of the three classes of mutants indicating that the buried residues were not recognition signals. In fact, Mm‐Cpn recognized the HγD‐Crys mutants better than (wild‐type) WT and refolded most mutant HγD‐Crys to levels twice that of WT HγD‐Crys. This presumably represents the increased population or longer lifetimes of the partially folded intermediates of the mutant proteins. The results suggest that Mm‐Cpn does not recognize the features of HγD‐Crys tested—paired aromatics, exposed domain interface, or destabilized core—but rather recognizes other features of the partially folded β‐sheet conformation that are absent or inaccessible in the native state of HγD‐Crys.