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The N‐terminal domain of Escherichia coli ClpB enhances chaperone function
Author(s) -
Chow I-Ting,
Barnett Micheal E.,
Zolkiewski Michal,
Baneyx François
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.06.055
Subject(s) - clpb , escherichia coli , chaperone (clinical) , protein folding , biology , biochemistry , heat shock protein , fusion protein , microbiology and biotechnology , biophysics , hsp70 , cold shock domain , protein aggregation , gene isoform , chemistry , recombinant dna , rna , gene , medicine , pathology
ClpB/Hsp104 collaborates with the Hsp70 system to promote the solubilization and reactivation of proteins that misfold and aggregate following heat shock. In Escherichia coli and other eubacteria, two ClpB isoforms (ClpB95 and ClpB80) that differ by the presence or absence of a highly mobile 149‐residues long N‐terminus domain are synthesized from the same transcript. Whether and how the N‐domain contributes to ClpB chaperone activity remains controversial. Here, we show that, whereas fusion of a 20‐residues long hexahistidine extension to the N‐terminus of ClpB95 interferes with its in vivo and in vitro activity, the same tag has no detectable effect on ClpB80 function. In addition, ClpB95 is more effective than ClpB80 at restoring the folding of the model protein preS2‐β‐galactosidase as stress severity increases, and is superior to ClpB80 in improving the high temperature growth and low temperature recovery of dnaK756 Δ clpB cells. Our results are consistent with a model in which the N‐domain of ClpB95 maximizes substrate processing under conditions where the cellular supply of free DnaK–DnaJ is limiting.