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Keywords: alkaliphiles, biotechnology, serpentinization, ATP synthase, Bacillus pseudofirmus OF4, bioenergetics, proton-motive force

… 1]: ‘the observed lateral variation in the proton-motive force necessitates a modification to Peter Mitchell's chemiosmotic proposal’. In other words, the experimentally proven lateral proton motive force is in line with the hypothesis of localized coupling.

Multiple strategies are hypothesized to be involved in enabling alkaliphiles to circumvent the challenge of a low bulk proton-motive force energizing proton-coupled ATP synthesis at high pH.

2. Total proton motive force (∑Δp) is suggested to be predominantly related to ΔpRNA and regulated by the capacity of the proton sink combined with activity of the electron transport chain (ETC):

1. The total proton motive force (∑Δp) is defined as protons entrapped in an RNA-base proton sink (ΔpRNA: latent Δp) together with free protons (Δpfree) in the IMS released from the proton sink:

Finally, it is curious to explore whether energetic calculations based on the proposed revised chemiosmosis agree with that of the original version of the theory. According to the original theory, the synthesis of ATP requires a proton motive force of 210 mV:

… Another hurdle in diffusion of protein from the “source” to the “sink” is permeability of the mitochondrial inner membrane to protons, which increases non-linearly with respect to proton motive force (Δp) [6,7]. According to chemiosmosis theory, a proton motive force of 210 mV is required to …

… In the presence of free geochemical proton gradients, protocells in vents can adapt to a sodium-motive force, all the while being powered by a proton-motive force. Eventually, cell membranes became tight to Na+, if not H+. So how did active pumping originate?

The energy stored in mitochondrial membrane potential (also known as “proton motive force”) can also be utilized to generate heat or to import calcium or proteins into the mitochondrion via uncoupling the transport of electrons from ATP production, which processes serve adaptive purposes. The proportion of dietary calories …

As to the driving-force dependence of mitochondrial transporters, it should be remembered that substrate oxidation by the mitochondrial respiratory chain is accompanied by protons ejection in the intermembrane space, thus generating the proton motive force (pmf). Pmf represents the driving force not only for ATP synthesis but …

… Soon, a Donnan equilibrium is established, in which the electrical charge across the membrane balances the concentration gradient, annulling the proton-motive force. This problem is only unmasked if the membrane can actually hold an electric charge, which is to say, only if the membrane has become impermeable …

Mitochondrial ATP synthesis is driven by harnessing the electrochemical gradient of protons (proton motive force) across the mitochondrial inner membrane via the process of chemiosmosis. While there is consensus that the proton gradient is generated by components of the electron transport chain, the mechanism by which protons are …

… Thus, ATP synthase physically shapes the membrane environment to optimize the proton motive force, ensuring that ATP generation remains both efficient and flexible [106, 107].

… The electron transfer reactions catalyzed by complexes I, III, and IV are coupled to the generation of the proton motive force. The latter is used by ATP synthase (FoF1-ATP synthase or complex V) to produce ATP.

The thylakoid proton motive force (pmf, ΔμH+) comprises two thermodynamically interchangeable components: the transmembrane electric potential (Δψ) and the pH gradient (ΔpH). However, Δψ and ΔpH are not physiologically equivalent, because ΔpH directly sets lumen pH—the chemical signal that engages rapid photoprotective feedbacks—whereas Δψ reflects the …

… Under this condition, a reported energetic contribution of 10 mV by membrane potential of state 4 mitochondria via Donnan effect [44] could provide the 210 mV of proton motive force required for ATP synthesis. Based on these calculations, it appears that energetic estimates of the revised chemiosmosis correspond …

… The proton motive force generated by type I NADH dehydrogenase and the terminal oxidases is used by FoF1-ATP synthase to make ATP [113,114,115]. Being a true proton pump, cytochrome bo3 produces the proton motive force with higher efficiency as compared to the evolutionarily unrelated bd …

… Oxidative phosphorylation couples electron transfer through respiratory complexes I–IV to proton translocation across the inner mitochondrial membrane, generating a proton motive force that drives ATP synthase (complex V). ANT completes this system by catalyzing the electrogenic exchange of ADP3− and ATP4−, thereby maintaining cytosolic ATP/ADP ratios …

… Complexes I, III, and IV (proton pumps) translocate protons into the inter-membrane space giving rise to a ΔpH which, coupled to the inner membrane electric potential (Δψm), generates the proton-motive force (ΔμH+ or Δp), driving, in the end, ATP synthesis.

… This “source-to-sink” proximity creates a steep local pH gradient and an enhanced proton motive force specifically around the ATP synthase, forcing protons to flow through the catalytic motor rather than dissipating into the bulk matrix. This kinetic coupling ensures that ATP generation remains efficient even when …