title: DnaJ recruits DnaK to protein aggregates.
abstract: Thermal stress might lead to protein aggregation in the cell. Reactivation of protein aggregates depends on Hsp100 and Hsp70 chaperones. We focus in this study on the ability of DnaK, the bacterial representative of the Hsp70 family, to interact with different aggregated model substrates. Our data indicate that DnaK binding to large protein aggregates is mediated by DnaJ, and therefore it depends on its affinity for the cochaperone. Mutations in the structural region of DnaK known as the "latch" decrease the affinity of the chaperone for DnaJ, resulting in a defective activity as protein aggregate-removing agent. As expected, the chaperone activity is recovered when DnaJ concentration is raised to overcome the lower affinity of the mutant for the cochaperone, suggesting that a minimum number of aggregate-bound DnaK molecules is necessary for its efficient reactivation. Our results provide the first experimental evidence of DnaJ-mediated recruiting of ATP-DnaK molecules to the aggregate surface.
authors.affiliation: Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
authors.forename: Sergio P
authors.initials: SP
authors.lastname: Acebrón
authors.affiliation: Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Fernández-Sáiz
authors.affiliation: Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
authors.forename: Stefka G
authors.initials: SG
authors.lastname: Taneva
authors.affiliation: Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Moro
authors.affiliation: Unidad de Biofísica (Consejo Superior de Investigaciones Científicas/Universidad del País Vasco-Euskal Henriko Unibertsitatea) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, P.O. Box 644, Bilbao 48080, Spain. Electronic address: arturo.muga@ehu.es.
authors.forename: Arturo
authors.initials: A
authors.lastname: Muga
mesh_terms: D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008156:Luciferases / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D020349:Surface Plasmon Resonance
chemical_list: C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D050505:Mutant Proteins; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D008156:Luciferases; C063842:dnaK protein, E coli