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Temperature‐dependent regulation of Thermus thermophilus DnaK/DnaJ chaperones by DafA protein
Author(s) -
Mizutani Tadashi,
Nemoto Shohei,
Yoshida Masasuke,
Watanabe Yohei
Publication year - 2009
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2009.01357.x
Subject(s) - thermus thermophilus , chaperone (clinical) , biology , thermus , biochemistry , microbiology and biotechnology , escherichia coli , foldase , biophysics , thermophile , groel , enzyme , gene , medicine , pathology
DafA, a unique 8‐kDa protein found in Thermus thermophilus , assembles the chaperones DnaK and DnaJ to produce a DnaK 3 –DnaJ 3 –DafA 3 complex (KJA complex). Although, it is known that DafA is denatured irreversibly at nonphysiological 89 °C and the KJA complex dissociates into fully active DnaK and DnaJ, the function of the KJA complex is not fully understood. In this article, we report that the reversible dissociation of the KJA complex occurs in a temperature‐dependent manner even below physiological 75 °C and that excess DafA completely inhibits the chaperone activities of the DnaK system. The inhibited activities are not rescued by supplementing DnaK or DnaJ. The results indicate that DafA inhibits the chaperone activities of both DnaK and DnaJ by forming the KJA complex and can act as a thermosensor under both heat stress and optimal growth conditions.