Hierarchical Model for the Role of J-Domain Proteins in Distinct Cellular Functions
Hierarchical Model for the Role of J-Domain Proteins in Distinct Cellular Functions
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J 结构域蛋白在不同细胞功能中作用的分层模型
DOI：
10.1016/j.jmb.2020.166750
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Ogura T
中科院分区：
文献类型：
--
作者：
Sugimoto S;Yamanaka K;Niwa T;Terasawa Y;Kinjo Y;Mizunoe Y;Ogura T
在大肠杆菌中，主要的细菌Hsp 70系统由DnaK、三个J结构域蛋白（JDP：DnaJ、CbpA和DjlA）和核苷酸交换因子GrpE组成。JDP决定Hsp 70系统的底物特异性;然而，关于它们在细菌细胞功能中的特定作用的知识是有限的。在这项研究中，我们证明了JDP在热应激期间细菌存活中的作用，以及DnaK调节的卷曲细胞外淀粉样纤维的形成参与生物膜的形成。遗传分析表明，只有DnaJ是在高温下生存所必需的。另一方面，DnaJ或CbpA，但不是DjlA，足以激活卷曲产生中的DnaK。此外，几种活性降低的DnaK突变体能够补充E中curli产生的损失。coliΔdnaK，但不能恢复突变株在高温下的生长缺陷。生化分析表明，DnaJ和CbpA参与的主调节CsgD的表达，通过溶解MlrA，一个DNA结合转录激活剂的thecgD启动子。此外，DnaJ和CbpA还通过防止CsgA在细胞质中聚集而使CsgA保持在有易位能力的状态。我们的研究结果支持一个分层模型，其中JDP在Hsp 70系统中的作用根据个体细胞功能而不同。
InEscherichia coli, the major bacterial Hsp70 system consists of DnaK, three J-domain proteins (JDPs: DnaJ, CbpA, and DjlA), and nucleotide exchange factor GrpE. JDPs determine substrate specificity for the Hsp70 system; however, knowledge on their specific role in bacterial cellular functions is limited. In this study, we demonstrated the role of JDPs in bacterial survival during heat stress and the DnaK-regulated formation of curli—extracellular amyloid fibers involved in biofilm formation. Genetic analysis demonstrate that only DnaJ is essential for survival at high temperature. On the other hand, either DnaJ or CbpA, but not DjlA, is sufficient to activate DnaK in curli production. Additionally, several DnaK mutants with reduced activity are able to complement the loss of curli production inE. coliΔdnaK, whereas they do not recover the growth defect of the mutant strain at high temperature. Biochemical analyses reveal that DnaJ and CbpA are involved in the expression of the master regulator CsgD through the solubilization of MlrA, a DNA-binding transcriptional activator for thecsgDpromoter. Furthermore, DnaJ and CbpA also keep CsgA in a translocation-competent state by preventing its aggregation in the cytoplasm. Our findings support a hierarchical model wherein the role of JDPs in the Hsp70 system differs according to individual cellular functions.