First Evidence for Existence of an Uphill Electron Transfer through the bc 1 and NADH-Q Oxidoreductase Complexes of the Acidophilic Obligate Chemolithotrophic Ferrous Ion-Oxidizing Bacterium Thiobacillus ferrooxidans

摘要

The energy-dependent electron transfer pathway involved in the reduction of pyridine nucleotides which is required for CO₂fixation to occur in the acidophilic chemolithotrophic organismThiobacillus ferrooxidans was investigated using ferrocytochrome c as the electron donor. The experimental results show that this uphill pathway involves abc ₁ and an NADH-Q oxidoreductase complex functioning in reverse, using an electrochemical proton gradient generated by ATP hydrolysis. Based on these results, a model is presented to explain the balance of the reducing equivalent from ferrocytochrome c between the exergonic and endergonic electron transfer pathways.