title: Tellurite uptake by cells of the facultative phototroph Rhodobacter capsulatus is a Delta pH-dependent process.
abstract: The uptake by light-grown cells of Rhodobacter capsulatus of the highly toxic metalloid oxyanion tellurite (TeO(3)(2-)) was examined. We show that tellurite is rapidly taken up by illuminated cells in a process which is inhibited by the protonophore carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP) and by the K(+)/H(+) exchanger nigericin. Notably, the light-driven membrane potential (Delta psi) is enhanced by K(2)TeO(3)> or =200 microM. Further, tellurite uptake is largely insensitive to valinomycin, strongly repressed by the sulfhydryl reagent N-ethylethylmaleimide (NEM) and competitively inhibited by phosphate. We conclude that tellurite is transported into cells by a Delta pH-dependent, non-electrogenic process which is likely to involve the phosphate transporter (PiT family).
authors: Department of Biology, University of Bologna, 42 Irnerio, Bologna 40126, Italy.
authors: Francesca
authors: F
authors: Borsetti
authors: Antonio
authors: A
authors: Toninello
authors: Davide
authors: D
authors: Zannoni
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D004563:Electrochemistry / Q000379:methods; D005033:Ethylmaleimide / Q000031:analogs & derivatives / Q000494:pharmacology; D007700:Kinetics; D008027:Light; D008564:Membrane Potentials / Q000187:drug effects; D009550:Nigericin / Q000494:pharmacology; D009861:Onium Compounds / Q000032:analysis / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000032:analysis / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D018892:Proton-Motive Force; D016354:Rhodobacter capsulatus / Q000166:cytology / Q000378:metabolism*; D013691:Tellurium / Q000493:pharmacokinetics* / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D009861:Onium Compounds; D009943:Organophosphorus Compounds; D014634:Valinomycin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; C026660:tellurous acid; D013691:Tellurium; D005033:Ethylmaleimide; D009550:Nigericin; D010100:Oxygen; C013289:tetraphenylphosphonium