Examinando por Autor "Chasteen, T."

Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    Expression of the ubiE gene of Geobacillus stearothermophilus V in Escherichia coli K-12 mediates the evolution of selenium compounds into the headspace of selenite- and selenate-amended cultures
    (Elsevier [Former Publisher] Federation of European Biochemical Societies [Associate Organisation] Wiley [Commercial Publisher], 2006-01) Swearingen Jr., J.; Fuentes, D.; Araya, M.; Plishker, M.; Saavedra, C.; Chasteen, T.; Vasquez, C.
    The ubiE gene of Geobacillus stearothermophilus V, with its own promoter, was cloned and introduced into Escherichia coli. The cloned gene complemented the ubiE gene deficiency of E. coli AN70. In addition, the expression of this gene in E. coli JM109 resulted in the evolution of volatile selenium compounds when these cells were grown in selenite- or selenate-amended media. These compounds were dimethyl selenide and dimethyl diselenide
  • Miniatura
    Ítem
    Tellurite enters Escherichia coli mainly through the PitA phosphate transporter
    (Wiley, 2012-09) Elías, A.; Abarca, M.; Montes, R.; Chasteen, T.; Pérez-Donoso, J.; Vásquez, C.
    everal transporters suspected to be involved in tellurite uptake in Escherichia coli were analyzed. Results showed that the PitA phosphate transporter was related to tellurite uptake. Escherichia coli ΔpitA was approximately four-fold more tolerant to tellurite, and cell viability remained almost unchanged during prolonged exposure to the toxicant as compared with wild type or ΔpitB cells. Notably, reduced thiols (toxicant targets) as well as superoxide dismutase, catalase, and fumarase C activities did not change when exposing the ΔpitA strain to tellurite, suggesting that tellurite-triggered oxidative damage is attenuated in the absence of PitA. After toxicant exposure, remaining extracellular tellurite was higher in E. coli ΔpitA than in control cells. Whereas inductively coupled plasma atomic emission spectrometric studies confirmed that E. coli ΔpitA accumulates ~50% less tellurite than the other strains under study, tellurite strongly inhibited 32Pi uptake suggesting that the PitA transporter is one of the main responsible for tellurite uptake in this bacterium.