FIGURE 2.
Mechanisms by which a proton motive (membrane potential [Δψ] + transmembrane pH gradient [ZΔpH]) force can be generated in mycobacteria. (1) Cotransport of protons driven by solute (succinate) symport into the periplasm. (2) Redox-loop separation of charge; (mena)quinol oxidation results in proton release into the periplasm by virtue of (mena)quinol site proximity to the periplasm, while electrons are transferred to reduce a terminal electron acceptor (e.g., nitrate, fumarate) in the cytoplasm that results in neutralization of charge. (3) Proton translocation mediated by primary proton-pumping complexes (bc1-aa3 supercomplex).