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首页> 外文期刊>The FEBS journal >Conformational properties of bacterial DnaK and yeast mitochondrial Hsp70. Role of the divergent C-terminal alpha-helical subdomain
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Conformational properties of bacterial DnaK and yeast mitochondrial Hsp70. Role of the divergent C-terminal alpha-helical subdomain

机译：细菌DnaK和酵母线粒体Hsp70的构象性质。不同的C末端alpha螺旋子域的作用

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Among the eukaryotic members of the Hsp70 family, mitochondrial Hsp70 shows the highest degree of sequence identity with bacterial DnaK. Although they share a functional mechanism and homologous co-chaperones, they are highly specific and cannot be exchanged between Escherichia coli and yeast mitochondria. To provide a structural basis for this finding, we characterized both proteins, as well as two DnaK/mtHsp70 chimeras constructed by domain swapping, using biochemical and biophysical methods. Here, we show that DnaK and mtHsp70 display different conformational and biochemical properties. Replacing different regions of the DnaK peptide-binding domain with those of mtHsp70 results in chimeric proteins that: (a) are not able to support growth of an E. coli DnaK deletion strain at stress temperatures (e.g. 42 degrees C); (b) show increased accessibility and decreased thermal stability of the peptide-binding pocket; and (c) have reduced activation by bacterial, but not mitochondrial co-chaperones, as compared with DnaK. Importantly, swapping the C-terminal alpha-helical subdomain promotes a conformational change in the chimeras to an mtHsp70-like conformation. Thus, interaction with bacterial co-chaperones correlates well with the conformation that natural and chimeric Hsp70s adopt in solution. Our results support the hypothesis that a specific protein structure might regulate the interaction of Hsp70s with particular components of the cellular machinery, such as Tim44, so that they perform specific functions.
机译：在Hsp70家族的真核成员中，线粒体Hsp70与细菌DnaK的序列同一性最高。尽管它们具有相同的功能机制和同源的伴侣伴侣，但它们具有很高的特异性，不能在大肠杆菌和酵母线粒体之间交换。为提供此发现的结构基础，我们使用生化和生物物理方法对这两种蛋白质以及通过结构域交换构建的两个DnaK / mtHsp70嵌合体进行了表征。在这里，我们显示DnaK和mtHsp70显示不同的构象和生化特性。用mtHsp70替换DnaK肽结合结构域的不同区域会产生嵌合蛋白，这些嵌合蛋白：（a）在应激温度（例如42摄氏度）下无法支持大肠杆菌DnaK缺失菌株的生长; （b）显示肽结合袋的可及性增加并且热稳定性降低; （c）与DnaK相比，细菌（而非线粒体）伴侣伴侣的活化降低。重要的是，交换C末端的α-螺旋亚结构域可促进嵌合体中构象变化为mtHsp70样构象。因此，与细菌伴侣伴侣的相互作用与天然和嵌合的Hsp70s在溶液中所采用的构象很好地相关。我们的结果支持以下假设：特定的蛋白质结构可能会调节Hsp70与细胞机器特定组件（例如Tim44）的相互作用，从而使它们执行特定功能。

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