Bioenergetics and the Role of Soluble Cytochromes c for Alkaline Adaptation in Gram-Negative Alkaliphilic Pseudomonas

Figure 8

Hypothetical model of cytochrome c-552 function in respiratory system of P. alcaliphila AL15-. The function of cytochrome c-552 as an electron and H⁺ reserve enhances the function of terminal oxidation (cytochrome cb) at pH 10 under low-aeration intensity (H⁺-less and O₂-less condition). Owing to the large negative charge of electron, H⁺ is attracted by the reduced cytochrome c-552. Thus, owing to the large electron and H⁺ capacity of enhanced amount of cytochrome c-552, the cytochrome cb terminal oxidase can transfer electrons and F₁F₀-ATP synthase can translocate H⁺ at pH 10 under low-aeration intensity. The hypothetical model shows that cytochrome c-552 in large capacity in the periplasmic space plays the role of an “electron and H⁺ condenser” in terminal oxidation and F₁F₀-ATP synthase activation.