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Tellurite uptake by cells of the facultative phototroph Rhodobacter capsulatus is a ΔpH‐dependent process
Author(s) -
Borsetti Francesca,
Toninello Antonio,
Zani Davide
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01180-3
Subject(s) - chemistry , rhodobacter , nigericin , protonophore , inorganic chemistry , phosphate , rhodospirillales , oxyanion , membrane potential , membrane , biochemistry , mutant , catalysis , photosynthesis , gene
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 (Δ ψ ) is enhanced by K 2 TeO 3 ≥200 μM. 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 ΔpH‐dependent, non‐electrogenic process which is likely to involve the phosphate transporter (PiT family).