3.A.2.1.3
H⁺-translocating F-type ATPase. Evidence of the proximity of ATP synthase subunit 6 is in proximity to the membrane in the supramolecular form (Velours et al., 2011).  The structure of the intact monomeric ATP synthase from the fungus, Pichia angusta, has been solved by electron cryo-microscopy (Vinothkumar et al. 2016). The Mg²⁺ and Ca²⁺-dependent enzymes are both active, but exhibit quite different behaviors (Nesci et al. 2017). Dimerization is necessary to create the inner membrane folds (cristae) characteristic of mitochondria.  Using cryo-electron microscopy, Guo et al. 2017 determined the structure of the dimeric F_O complex from Saccharomyces cerevisiae at a resolution of 3.6 angstroms. The structure clarifies how the protons travel through the complex, how the complex dimerizes, and how the dimers bend the membrane to produce cristae. The crystal structure of the c-subunit ring with bound oligomycin revealed the inhibitor docked on the outer face of the proton-binding sites, deep in the transmembrane region (Zhou and Faraldo-Gómez 2018). A high resolution (3.7 Å) structure of the entire monomeric ATPase has been solved by cryo EM, suggesting how it is inhibited by oligomycin (Srivastava et al. 2018).  Absence of the e and g subunits decreases conductance of the F-ATP synthase channel about tenfold. Ablation of the first TMS of subunit b, which creates a distinct lateral domain with e and g, further affected channel activity. Thus, F-ATP synthase e, g and b subunits create a domain within the membrane that is critical for the generation of the high-conductance channel that is a prime candidate for formation of the permeability transition pore (PTP). Subunits e and g are only present in eukaryotes and may have evolved to confer this novel function to F-ATP synthases (Carraro et al. 2018). The translation rate of all yeast mitochondrial mRNAs, including all F-type ATPase subunits has been studied (Chicherin et al. 2021). Attenuated ADP-inhibition of F0F1 ATPase mitigates manifestations of mitochondrial dysfunction in yeast (Lapashina et al. 2022).