FIG 1.

Mycobacterial respiratory chain complexes generate the electrochemical gradient, providing the energy for the formation of ATP by the F₁F_o-ATP synthase. Complexes I (NDH) and II (SDH) oxidize NADH and succinate, respectively. These electrons are transferred to the mycobacterial cyt-bcc:aa₃ and cyt-bd oxidases to reduce oxygen to water. While complex I and the cyt-bcc:aa₃ pump protons into the intermembrane lumen to generate the proton gradient, the F_o domain of the F₁F_o ATP synthase uses these protons to drive ATP formation in the F₁ domain. The maintenance of a proton gradient and the regulation of ATP production are crucial parameters governing the survival of the bacterium.