title: Tellurite-mediated damage to the Escherichia coli NDH-dehydrogenases and terminal oxidases in aerobic conditions.
abstract: Escherichia coli exposed to tellurite shows augmented membrane lipid peroxidation and ROS content. Also, reduced thiols, protein carbonylation, [Fe-S] center dismantling, and accumulation of key metabolites occur in these bacteria. In spite of this, not much is known about tellurite effects on the E. coli electron transport chain (ETC). In this work, tellurite-mediated damage to the E. coli ETC's NADH dehydrogenases and terminal oxidases was assessed. Mutant lacking ETC components showed delayed growth, decreased oxygen consumption and increased ROS in the presence of the toxicant. Membranes from tellurite-exposed E. coli exhibited decreased oxygen consumption and dNADH/NADH dehydrogenase activity, showing an impairment of NDH-I but not of NDH-II activity. Regarding terminal oxidases, only the bo oxidase complex was affected by tellurite. When assaying NDH-I and NDH-II activity in the presence of superoxide, the NDH-I complex was preferentially damaged. The activity was partly restored in the presence of reducing agents, sulfide and Fe(2+) under anaerobic conditions, suggesting that damage affects NDH-I [4Fe-4S] centers. Finally, augmented membrane protein oxidation along with reduced oxidase activity was observed in the presence of the toxicant. Also, the increased expression of genes encoding alternative terminal oxidases probably reflects a cell's change towards anaerobic respiration when facing tellurite.
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile; Facultad de Ciencia, Universidad San Sebastián, Santiago, Chile.
authors.forename: Waldo A
authors.initials: WA
authors.lastname: Díaz-Vásquez
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: María J
authors.initials: MJ
authors.lastname: Abarca-Lagunas
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: Fabián A
authors.initials: FA
authors.lastname: Cornejo
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: Camilo A
authors.initials: CA
authors.lastname: Pinto
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Arenas
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile. Electronic address: claudio.vasquez@usach.cl.
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Vásquez
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D000693:Anaerobiosis / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D050050:Protein Carbonylation / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D013691:Tellurium / Q000633:toxicity*
chemical_list: D029968:Escherichia coli Proteins; D007527:Isoenzymes; D013481:Superoxides; D010088:Oxidoreductases; D009245:NADH Dehydrogenase; C026660:tellurous acid; D013691:Tellurium
keywords: Bacterial metabolism; E. coli; Electron transport chain; Enzyme inactivation; Membrane protein; NADH; NADH:ubiquinone oxidoreductase I; Oxidative damage; Tellurite; Terminal oxidase