title: The DnaK chaperone is necessary for alpha-complementation of beta-galactosidase in Escherichia coli.
abstract: We show here the involvement of the molecular chaperone DnaK from Escherichia coli in the in vivo alpha-complementation of the beta-galactosidase. In the dnaK756(Ts) mutant, alpha-complementation occurs when the organisms are grown at 30 degrees C but not at 37 or 40 degrees C, although these temperatures are permissive for bacterial growth. Plasmid-driven expression of wild-type dnaK restores the alpha-complementation in the mutant but also stimulates it in a dnaK(+) strain. In a mutant which contains a disrupted dnaK gene (DeltadnaK52::Cm(r)), alpha-complementation is also impaired, even at 30 degrees C. This observation provides an easy and original phenotype to detect subtle functional changes in a protein such as the DnaK756 chaperone, within the physiologically relevant temperature.
authors.affiliation: Institut de Biologie Physico-Chimique, U.P.R. 9073 du C.N.R.S. and Université Paris 7-Denis Diderot, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lopes Ferreira
authors.forename: Jean-Hervé
authors.initials: JH
authors.lastname: Alix
mesh_terms: D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D005816:Genetic Complementation Test; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D015151:Immunoblotting; D008969:Molecular Sequence Data; D001616:beta-Galactosidase / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D001616:beta-Galactosidase; C063842:dnaK protein, E coli