Functional analysis of CbpA, a DnaJ homolog and nucleoid-associated DNA-binding protein
Functional analysis of CbpA, a DnaJ homolog and nucleoid-associated DNA-binding protein
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DOI：
10.1074/jbc.m603365200
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发表时间：
2006-11-10
影响因子：
4.8
通讯作者：
Wickner, Sue
中科院分区：
文献类型：
--
作者：
Bird, Jeremy G.;Sharma, Suveena;Wickner, Sue
DnaK/Hsp70 蛋白是普遍保守的 ATP 依赖性分子伴侣，可帮助蛋白质采用并维持其天然构象。 DnaJ/Hsp40 和 GrpE 是协助 DnaK 的共伴侣。 CbpA 是大肠杆菌 DnaJ 同源物。它充当 dnaJ 突变的多拷贝抑制因子，并在蛋白质重塑反应中与 DnaK 和 GrpE 结合在体外发挥作用。 CbpA 与 DNA 非特异性结合，优先结合弯曲 DNA，是一种核仁相关蛋白。 CbpA 的 DNA 结合和共伴侣活性由 CbpM 调节，CbpM 是一种与 CbpA 特异性结合的小蛋白。为了鉴定参与 CbpA 与 CbpM 相互作用的 CbpA 区域以及参与 DNA 结合的区域，我们构建并表征了 CbpA 的缺失和取代突变体。我们发现 CbpA 通过其 N 端 J 结构域与 CbpM 相互作用。我们发现 J 结构域的 C 端区域是 DNA 结合所必需的。此外，我们发现 CbpM 相互作用、DNA 结合和共伴侣活性是可分离的；一些突变体精通某些功能，但在其他功能上有缺陷。
DnaK/Hsp70 proteins are universally conserved ATP-dependent molecular chaperones that help proteins adopt and maintain their native conformations. DnaJ/Hsp40 and GrpE are co-chaperones that assist DnaK. CbpA is an Escherichia coli DnaJ homolog. It acts as a multicopy suppressor for dnaJ mutations and functions in vitro in combination with DnaK and GrpE in protein remodeling reactions. CbpA binds nonspecifically to DNA with preference for curved DNA and is a nucleoid-associated protein. The DNA binding and co-chaperone activities of CbpA are modulated by CbpM, a small protein that binds specifically to CbpA. To identify the regions of CbpA involved in the interaction of CbpA with CbpM and those involved in DNA binding, we constructed and characterized deletion and substitution mutants of CbpA. We discovered that CbpA interacted with CbpM through its N-terminal J-domain. We found that the region C-terminal to the J-domain was required for DNA binding. Moreover, we found that the CbpM interaction, DNA binding, and co-chaperone activities were separable; some mutants were proficient in some functions and defective in others.