title: DnaK dependence of mutant ethanol oxidoreductases evolved for aerobic function and protective role of the chaperone against protein oxidative damage in Escherichia coli.
abstract: The adhE gene of Escherichia coli encodes a multifunctional ethanol oxidoreductase (AdhE) that catalyzes successive reductions of acetyl-CoA to acetaldehyde and then to ethanol reversibly at the expense of NADH. Mutant JE52, serially selected for acquired and improved ability to grow aerobically on ethanol, synthesized an AdhE(A267T/E568K) with two amino acid substitutions that sequentially conferred improved catalytic properties and stability. Here we show that the aerobic growth ability on ethanol depends also on protection of the mutant AdhE against metal-catalyzed oxidation by the chaperone DnaK (a member of the Hsp70 family). No DnaK protection of the enzyme is evident during anaerobic growth on glucose. Synthesis of DnaK also protected E. coli from H2O2 killing under conditions when functional AdhE is not required. Our results therefore suggest that, in addition to the known role of protecting cells against heat stress, DnaK also protects numerous kinds of proteins from oxidative damage.
authors.affiliation: Departamento de Biologia Molecular y Biotecnologia, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, P.O. Box 70-228, 04510 Mexico City, Mexico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Echave
authors.forename: M Angel
authors.initials: MA
authors.lastname: Esparza-Cerón
authors.forename: Elisa
authors.initials: E
authors.lastname: Cabiscol
authors.forename: Jordi
authors.initials: J
authors.lastname: Tamarit
authors.forename: Joaquim
authors.initials: J
authors.lastname: Ros
authors.forename: Jorge
authors.initials: J
authors.lastname: Membrillo-Hernández
authors.forename: E C C
authors.initials: EC
authors.lastname: Lin
mesh_terms: D000332:Aerobiosis; D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000378:metabolism*; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D000431:Ethanol / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000502:physiology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D009097:Multienzyme Complexes; D000431:Ethanol; D000426:Alcohol Dehydrogenase; C068383:adhE protein, E coli; D000445:Aldehyde Oxidoreductases; C063842:dnaK protein, E coli