• Orbit mini

    Simultaneous recording from four lipid bilayers

2019 - Arg-8 of yeast subunit e contributes to the stability of F-ATP synthase dimersand to the generation of the full-conductance megachannel

 Icon Orbit Mini   Orbit mini publication in Journal of Biological Chemistry (2019)

Authors:
Guo L., Carraro M., Carrer A., Minervini G., Urbani A., Masgras I., Tosatto S.C.E., Szabò I., Bernardi P., Lippe G.

Journal:
Journal of Biological Chemistry (2019) doi: 10.1074/jbc.RA119.008775


Abstract:

The mitochondrial F-ATP synthase is a complex molecular motor arranged in V-shaped dimers that is responsible for most cellular ATP synthesis in aerobic conditions. In the yeast F-ATP synthase, subunits e and g of the FO sector constitute a lateral domain, which is required for dimer stability and cristae formation. Here, by using site-directed mutagenesis we identified Arg-8 of subunit e as a critical residue in mediating interactions between subunits e and g, most likely through an interaction with Glu-83 of subunit g. Consistent with this hypothesis (i) substitution of Arg-8 in subunit e (eArg-8) with Ala or Glu or of Glu-83 in subunit g (gGlu-83) with Ala or Lys destabilized the digitonin-extracted F-ATP synthase, resulting in decreased dimer formation, as revealed by blue-native electrophoresis; and (ii) simultaneous substitution of eArg-8 with Glu and of gGlu-83 with Lys rescued digitonin-stable F-ATP synthase dimers. When tested in lipid bilayers for generation of Ca2+-dependent channels, wild-type dimers displayed the high-conductance channel activity expected for the mitochondrial megachannel/permeability transition pore, whereas dimers obtained at low digitonin concentrations from the Arg-8 variants displayed currents of strikingly small conductance. Remarkably, double replacement of eArg-8 with Glu and of gGlu-83 with Lys restored high-conductance channels indistinguishable from those seen in wild-type enzymes. These findings suggest that the interaction of subunit e with subunit g is important for generation of the full-conductance megachannel from F-ATP synthase.


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