title: Escherichia coli 6-phosphogluconate dehydrogenase aids in tellurite resistance by reducing the toxicant in a NADPH-dependent manner.
abstract: Exposure to the tellurium oxyanion tellurite (TeO3(2-)) results in the establishment of an oxidative stress status in most microorganisms. Usually, bacteria growing in the presence of the toxicant turn black because of the reduction of tellurite (Te(4+)) to the less-toxic elemental tellurium (Te(0)). In vitro, at least part of tellurite reduction occurs enzymatically in a nicotinamide dinucleotide-dependent reaction. In this work, we show that TeO3(2-) reduction by crude extracts of Escherichia coli overexpressing the zwf gene (encoding glucose-6-phosphate dehydrogenase) takes place preferentially in the presence of NADPH instead of NADH. The enzyme responsible for toxicant reduction was identified as 6-phosphogluconate dehydrogenase (Gnd). The gnd gene showed a subtle induction at short times after toxicant exposure while strains lacking gnd were more susceptible to the toxicant. These results suggest that both NADPH-generating enzymes from the pentose phosphate shunt may be involved in tellurite detoxification and resistance in E. coli.
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: J M
authors.initials: JM
authors.lastname: Sandoval
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: F A
authors.initials: FA
authors.lastname: Arenas
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: J A
authors.initials: JA
authors.lastname: García
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile; Facultad de Ciencias de la Salud, Universidad San Sebastián, Santiago, Chile.
authors.forename: W 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: M
authors.initials: M
authors.lastname: Valdivia-González
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Sabotier
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: C C
authors.initials: CC
authors.lastname: Vásquez
mesh_terms: D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D008658:Inactivation, Metabolic; D009249:NADP / Q000378:metabolism*; D010084:Oxidation-Reduction; D010734:Phosphogluconate Dehydrogenase / Q000378:metabolism*; D013691:Tellurium / Q000378:metabolism* / Q000633:toxicity
chemical_list: D009249:NADP; D010734:Phosphogluconate Dehydrogenase; C026660:tellurous acid; D013691:Tellurium
keywords: Escherichia coli; G6PDH; Gnd protein; NADPH; Tellurite reduction