CbpA, a DnaJ homolog, is a DnaK co-chaperone, and its activity is modulated by CbpM
CbpA, a DnaJ homolog, is a DnaK co-chaperone, and its activity is modulated by CbpM
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DOI：
10.1074/jbc.m404862200
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发表时间：
2004-08-06
影响因子：
4.8
通讯作者：
Wickner, S
中科院分区：
文献类型：
--
作者：
Chae, C;Sharma, S;Wickner, S
DNAK伴侣系统由DNAK、DNAJ和GRPE组成，在正常生长和应激条件下都能重塑和复性蛋白质。CBPA是大肠杆菌中几个DNAJ类似物之一，被认为是dna J突变的多拷贝抑制因子，并非特异性地与DNA结合，并优先与弯曲DNA结合。我们在体外发现CbpA作为DNAJ样的辅助伴侣发挥作用。CBPA与DNAK和GRPE发生依赖于ATP的反应，将P1REPA的失活二聚体重塑为与P1DNA结合的活性单体。此外，CbpA与DNAK一起参与了一个ATP依赖的反应，以防止变性罗丹明的聚集。CBPA基因位于一个带有开放阅读框yccD的操纵子中，它编码的蛋白质与嗜热嗜热菌的Dafa有一定的同源性。DafA是一种蛋白质，它是组装环状颗粒所必需的，环状颗粒中包含嗜热梭菌DNAK、DNAJ和DafA的每一个三聚体。由于其与CbpA具有潜在的功能关系，因此分离到了YccD。纯化的YccD特异性地抑制CbpA的辅伴侣活性和DNA结合活性，提示YccD调节CbpA的活性。我们将yccd基因的产物CBPM命名为“CbpA调节器”。
The DnaK chaperone system, consisting of DnaK, DnaJ, and GrpE, remodels and refolds proteins during both normal growth and stress conditions. CbpA, one of several DnaJ analogs in Escherichia coli, is known to function as a multicopy suppressor for dnaJ mutations and to bind nonspecifically to DNA and preferentially to curved DNA. We found that CbpA functions as a DnaJ-like co-chaperone in vitro. CbpA acted in an ATP-dependent reaction with DnaK and GrpE to remodel inactive dimers of plasmid P1 RepA into monomers active in P1 DNA binding. Additionally, CbpA participated with DnaK in an ATP-dependent reaction to prevent aggregation of denatured rhodanese. The cbpA gene is in an operon with an open reading frame, yccD, which encodes a protein that has some homology to DafA of Thermus thermophilus. DafA is a protein required for the assembly of ring-like particles that contain trimers each of T. thermophilus DnaK, DnaJ, and DafA. The E. coli YccD was isolated because of its potential functional relationship to CbpA. Purified YccD specifically inhibited both the co-chaperone activity and the DNA binding activity of CbpA, suggesting that YccD modulates the activity of CbpA. We named the product of the yccD gene CbpM for "CbpA modulator."