title: Cooperative action of Escherichia coli ClpB protein and DnaK chaperone in the activation of a replication initiation protein.
abstract: The Escherichia coli molecular chaperone protein ClpB is a member of the highly conserved Hsp100/Clp protein family. Previous studies have shown that the ClpB protein is needed for bacterial thermotolerance. Purified ClpB protein has been shown to reactivate chemically and heat-denatured proteins. In this work we demonstrate that the combined action of ClpB and the DnaK, DnaJ, and GrpE chaperones leads to the activation of DNA replication of the broad-host-range plasmid RK2. In contrast, ClpB is not needed for the activation of the oriC-dependent replication of E. coli. Using purified protein components we show that the ClpB/DnaK/DnaJ/GrpE synergistic action activates the plasmid RK2 replication initiation protein TrfA by converting inactive dimers to an active monomer form. In contrast, Hsp78/Ssc1/Mdj1/Mge1, the corresponding protein system from yeast mitochondria, cannot activate the TrfA replication protein. Our results demonstrate for the first time that the ClpB/DnaK/DnaJ/GrpE system is involved in protein monomerization and in the activation of a DNA replication factor.
authors.affiliation: Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, 24 Kladki, 80 822 Gdansk, Poland. igor@biotech.univ.gda.pl
authors.forename: Igor
authors.initials: I
authors.lastname: Konieczny
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Liberek
mesh_terms: D004261:DNA Replication; D019281:Dimerization; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D015800:Protozoan Proteins; D049071:Endopeptidase Clp; C063842:dnaK protein, E coli; C095049:ClpB protein, Leishmania