Structural Basis of the Regulation of the CbpA Co-chaperone by its Specific Modulator CbpM
Structural Basis of the Regulation of the CbpA Co-chaperone by its Specific Modulator CbpM
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DOI：
10.1016/j.jmb.2010.03.006
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发表时间：
2010-04-23
影响因子：
5.6
通讯作者：
Ekiel, Irena
中科院分区：
文献类型：
--
作者：
Sarraf, Naghmeh S.;Baardsnes, Jason;Ekiel, Irena
CbpA是大肠杆菌DnaJ同源物之一，在DnaK分子伴侣系统中充当共分子伴侣。尽管它在结构域和功能上与DnaJ具有广泛的相似性，但CbpA具有通过小蛋白CbpM介导的独特且特异的调节机制。CbpA和CbpM在细菌中高度保守。早期的研究表明，CbpM与CbpA的N-末端J-结构域相互作用，抑制其共伴侣活性，但这种相互作用的结构基础尚不清楚。在这里，我们结合了NMR光谱，定点诱变和表面等离子体共振表征的CbpA/CbpM在分子水平上的相互作用。我们已经确定了解决方案的CbpA J-结构域的结构和映射的残基被扰动后，CbpM结合。NMR数据定义了一个广泛的区域上的螺旋α 2和α 3参与的相互作用。定点诱变已用于进一步描绘CbpA J结构域/CbpM界面。我们发现，结合位点的CbpM和DnaK上的CbpA J-结构域重叠，这表明之间的竞争DnaK和CbpM结合到CbpA作为一种机制，CbpA调节。本研究还通过鉴定差异结合的关键残基，解释了CbpM对CbpA与DnaJ的特异性。皇冠版权所有（C）2010由爱思唯尔有限公司出版。保留所有权利。
CbpA, one of the Escherichia coli DnaJ homologues, acts as a co-chaperone in the DnaK chaperone system. Despite its extensive similarity in domain structure and function to DnaJ, CbpA has a unique and specific regulatory mechanism mediated through the small protein CbpM. Both CbpA and CbpM are highly conserved in bacteria. Earlier studies showed that CbpM interacts with the N-terminal J-domain of CbpA inhibiting its co-chaperone activity but the structural basis of this interaction is not known. Here, we have combined NMR spectroscopy, site-directed mutagenesis and surface plasmon resonance to characterize the CbpA/CbpM interaction at the molecular level. We have determined the solution structure of the CbpA J-domain and mapped the residues that are perturbed upon CbpM binding. The NMR data defined a broad region on helices alpha 2 and alpha 3 as involved in the interactions. Site-directed mutagenesis has been used to further delineate the CbpA J-domain/CbpM interface. We show that the binding sites of CbpM and DnaK on CbpA J-domain overlap, which suggests a competition between DnaK and CbpM for binding to CbpA as a mechanism for CbpA regulation. This study also provides the explanation for the specificity of CbpM for CbpA versus DnaJ, by identifying the key residues for differential binding. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.