Sodium-dependent succinate uptake in purple bacterium Ectothiorhodospira shaposhnikovii.

Succinate, malate and fumarate uptake in purple sulfur bacterium Ectothiorhodospira shaposhnikovii,. strain 1 K MSU, obligatorily depends on the presence of Na+. Other monovalent cations such as K+, Li+, NH4+ could not replace Na+. Experiments with energy-depleted cells have shown that succinate uptake against its concentration gradient can be energized by artifically imposed sodium gradients (delta pNa). An artificial membrane potential (inside negative) inhibited delta pNa-driven succinate uptake at pH 7.0 but stimulated it at pH 9.0. The results confirm the suggestion that succinate uptake in E. shaposhnikovii is carried out in symport with Na+.