A small heat shock protein cooperates with heat shock protein 70 systems to reactivate a heat-denatured protein
A small heat shock protein cooperates with heat shock protein 70 systems to reactivate a heat-denatured protein
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DOI：
10.1104/pp.122.1.189
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发表时间：
2000-01-01
期刊：
影响因子：
7.4
通讯作者：
Vierling, E
中科院分区：
文献类型：
--
作者：
Lee, GJ;Vierling, E
小分子热激蛋白（Small heat shock proteins，sHsps）是一类在原核生物和真核生物中高度保守的热诱导蛋白，在植物中含量非常丰富。最近的体外数据表明，sHsps作为分子伴侣，以防止热聚集的蛋白质结合非天然的中间体，然后可以重新折叠在一个ATP依赖的方式由其他伴侣。我们使用热变性萤火虫荧光素酶（Luc）结合豌豆（豌豆）Hsp18.1作为一个模型来定义的最小分子伴侣系统所需的sHSP结合底物的重折叠。热变性的Luc与Hsp18.1的结合可以用来自不同真核生物的Hsc/Hsp 70加上DnaJ同源物Hdj 1和Ydj 1（最大= 97%Luc再活化，k（ob）= 1.0 x 10（-2）/min），或者用原核大肠杆菌DnaK加上DnaJ和GrpE（100%Luc再活化，k（ob）= 11.3 x 10（-2）/min）有效地重折叠。此外，我们表明，热休克蛋白18.1是更有效地防止Luc热聚集比Hsc 70或DnaK系统，和热休克蛋白18.1提高重折叠Luc的产量，即使当其他分子伴侣存在于热灭活。这些发现整合了sHsps的聚集预防活性与Hsp 70系统的蛋白质折叠活性，并定义了进一步研究sHsp作用机制的体外系统。
Small heat shock proteins (sHsps) are a diverse group of heat-induced proteins that are conserved in prokaryotes and eukaryotes and are especially abundant in plants. Recent in vitro data indicate that sHsps act as molecular chaperones to prevent thermal aggregation of proteins by binding non-native intermediates, which can then be refolded in an ATP-dependent fashion by other chaperones. We used heat-denatured firefly luciferase (Luc) bound to pea (Pisum sativum) Hsp18.1 as a model to define the minimum chaperone system required for refolding of a sHsp-bound substrate. Heat-denatured Luc bound to Hsp18.1 was effectively refolded either with Hsc/Hsp70 from diverse eukaryotes plus the DnaJ homologs Hdj1 and Ydj1 (maximum = 97% Luc reactivation with k(ob) = 1.0 x 10(-2)/min), or with prokaryotic Escherichia coli DnaK plus DnaJ and GrpE (100% Luc reactivation, k(ob) = 11.3 x 10(-2)/min). Furthermore, we show that Hsp18.1 is more effective in preventing Luc thermal aggregation than the Hsc70 or DnaK systems, and that Hsp18.1 enhances the yields of refolded Luc even when other chaperones are present during heat inactivation. These findings integrate the aggregation-preventive activity of sHsps with the protein-folding activity of the Hsp70 system and define an in vitro system for further investigation of the mechanism of sHsp action.