Proton-coupled bioenergetic processes in extremely alkaliphilic bacteria.

摘要: Oxidative phosphorylation, which involves an exclusively proton-coupled ATP synthase, and pH homeostasis, depends upon electrogenic antiport of cytoplasmic Na+ in exchange for H+, are the two known bioenergetic processes that require inward proton translocation extremely alkaliphilic bacteria. Energy coupling to oxidative phosphorylation is particularly difficult fit a strictly chemiosmotic model because low bulk electrochemical gradient follows from maintenance just above 8 during growth at 10.5 higher. A large quantitative variable discrepancy between putative driving force potential results. This compounded by nonequivalence respiration-dependent gradients artificially imposed ones energizing synthesis, apparent requirement specific respiratory chain complexes do not relate solely their role generation gradients. Special features synthase may contribute mode energization, as novel cycle extraordinary capacity extreme alkaliphiles achieve homeostasis at, or sudden shifts to, external above.