Tellurite uptake by cells of the facultative phototroph Rhodobacter capsulatus is a ΔpH‐dependent process

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Abstract
The uptake by light-grown cells of Rhodobacter capsulatus of the highly toxic metalloid oxyanion tellurite (TeO32−) 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 (Δψ) is enhanced by K2TeO3≥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)

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