The DnaK chaperone machinery converts the native FlhD2C2 hetero‐tetramer into a functional transcriptional regulator of flagellar regulon expression in Salmonella
The DnaK chaperone machinery converts the native FlhD2C2 hetero‐tetramer into a functional transcriptional regulator of flagellar regulon expression in Salmonella
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DOI：
10.1111/j.1365-2958.2005.05016.x
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发表时间：
2006-02
影响因子：
3.6
通讯作者：
A. Takaya;M. Matsui;T. Tomoyasu;Michihiro Kaya;Tomoko Yamamoto
中科院分区：
文献类型：
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作者：
A. Takaya;M. Matsui;T. Tomoyasu;Michihiro Kaya;Tomoko Yamamoto
DnaK分子伴侣与许多未折叠的多肽非特异性结合，也与特异性底物选择性结合。虽然它参与靶向未折叠的多肽以帮助正确折叠是有据可查的，但关于它在靶向折叠的多肽中的作用知之甚少。我们表明，DnaK调节沙门氏菌鞭毛调节子的表达，通过调节FlhD和FlhC蛋白，其功能作为主调节器在包括三类基因的转录层次的顶点。FlhD和FlhC形成FlhD2C2复合物，其激活2类基因的σ70启动子。在ΔdnaK细胞中，FlhD和FlhC蛋白似乎组装成异源四聚体FlhD2C2，但该复合物在2类基因转录中不完全活跃，表明DnaK伴侣蛋白参与激活天然FlhD2C2复合物成为鞭毛调节子表达的调节剂。这是第一次，参与DnaK伴侣机制激活折叠寡聚化蛋白质已被证明。
The DnaK chaperone binds non‐specifically to many unfolded polypeptides and also binds selectively to specific substrates. Although its involvement in targeting the unfolded polypeptides to assist proper folding is well documented, less is known about its role in targeting the folded polypeptides. We demonstrate that DnaK regulates the expression of the Salmonella flagellar regulon by modulating the FlhD and FlhC proteins, which function as master regulators at the apex of a transcription hierarchy comprising three classes of genes. FlhD and FlhC form an FlhD2C2 complex that activates σ70 promoter of class 2 genes. In ΔdnaK cells, FlhD and FlhC proteins seemed to be assembled into hetero‐tetrameric FlhD2C2 but the complex was not fully active in class 2 gene transcription, suggesting that the DnaK chaperone is involved in activating native FlhD2C2 complex into a regulator of flagellar regulon expression. This is the first time that involvement of the DnaK chaperone machinery in activating folded oligomerized proteins has been demonstrated.