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The DnaK chaperone machinery converts the native FlhD 2 C 2 hetero‐tetramer into a functional transcriptional regulator of flagellar regulon expression in Salmonella
Author(s) -
Takaya Akiko,
Matsui Mari,
Tomoyasu Toshifumi,
Kaya Michihiro,
Yamamoto Tomoko
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.05016.x
Subject(s) - regulon , biology , tetramer , chaperone (clinical) , regulator , microbiology and biotechnology , escherichia coli proteins , transcriptional regulation , bacterial protein , computational biology , gene expression , biochemistry , gene , enzyme , medicine , pathology
Summary 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 FlhD 2 C 2 complex that activates σ 70 promoter of class 2 genes. In Δ dnaK cells, FlhD and FlhC proteins seemed to be assembled into hetero‐tetrameric FlhD 2 C 2 but the complex was not fully active in class 2 gene transcription, suggesting that the DnaK chaperone is involved in activating native FlhD 2 C 2 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.