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Stabilization of Fo/Vo/Ao by a radial electric field

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ABSTRACT

The membrane domain of rotary ATPases (Fo/Vo/Ao) contains a membrane-embedded rotor ring which rotates against an adjacent cation channel-forming subunit during catalysis. The mechanism that allows stabilization of the highly mobile and yet tightly connected domains during operation while not impeding rotation is unknown. Remarkably, all known ATPase rotor rings are filled by lipids. In the crystal structure of the rotor ring of a V-ATPase from Enterococcus hirae the ring filling lipids form a proper membrane that is lower with respect to the embedding membrane surrounding both subunits. I propose first, that a vertical shift between lumenal lipids and embedding outside membrane is a general feature of rotor rings and second that it leads to a radial potential fall-off between rotor ring and cation channel, creating attractive forces that impact rotor-stator interaction in Fo/Vo/Ao during rotation.

No MeSH data available.


Schematic representation of rotary ATPases. Rotor parts are depicted in red, stator parts in blue. Cation channel forming stator and membrane embedded cation transporting rotor ring are highlighted by darker hues.
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f1-7_99: Schematic representation of rotary ATPases. Rotor parts are depicted in red, stator parts in blue. Cation channel forming stator and membrane embedded cation transporting rotor ring are highlighted by darker hues.

Mentions: Rotary ATPases (F-, V- and A-ATPases) are universal energy converters central to the energy metabolism of all cellular life. They either utilize an electrochemical potential in the form of proton or sodium cation gradients across a biological membrane to make ATP from ADP and Pi or pump protons or sodium cations across a biological membrane at the expense of ATP hydrolysis1–3. Rotary ATPases are organized in two domains: a water-soluble, cytosolic domain which is termed F1, V1 or A1, and a membrane-embedded domain which is termed Fo, Vo or Ao. Energy conversion in rotary ATPases is achieved through the combination of two opposing rotary motors, which are connected by a central shaft and a variable number of lateral stalks4. While the soluble F1, V1 or A1 domain harbors catalytic binding sites for ATP, the conversion of electrochemical energy is catalyzed by the membrane-bound Fo, Vo or Ao motor. See Figure 1 for a cartoon depicting the general organization of rotary ATPases.


Stabilization of Fo/Vo/Ao by a radial electric field
Schematic representation of rotary ATPases. Rotor parts are depicted in red, stator parts in blue. Cation channel forming stator and membrane embedded cation transporting rotor ring are highlighted by darker hues.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036770&req=5

f1-7_99: Schematic representation of rotary ATPases. Rotor parts are depicted in red, stator parts in blue. Cation channel forming stator and membrane embedded cation transporting rotor ring are highlighted by darker hues.
Mentions: Rotary ATPases (F-, V- and A-ATPases) are universal energy converters central to the energy metabolism of all cellular life. They either utilize an electrochemical potential in the form of proton or sodium cation gradients across a biological membrane to make ATP from ADP and Pi or pump protons or sodium cations across a biological membrane at the expense of ATP hydrolysis1–3. Rotary ATPases are organized in two domains: a water-soluble, cytosolic domain which is termed F1, V1 or A1, and a membrane-embedded domain which is termed Fo, Vo or Ao. Energy conversion in rotary ATPases is achieved through the combination of two opposing rotary motors, which are connected by a central shaft and a variable number of lateral stalks4. While the soluble F1, V1 or A1 domain harbors catalytic binding sites for ATP, the conversion of electrochemical energy is catalyzed by the membrane-bound Fo, Vo or Ao motor. See Figure 1 for a cartoon depicting the general organization of rotary ATPases.

View Article: PubMed Central - PubMed

ABSTRACT

The membrane domain of rotary ATPases (Fo/Vo/Ao) contains a membrane-embedded rotor ring which rotates against an adjacent cation channel-forming subunit during catalysis. The mechanism that allows stabilization of the highly mobile and yet tightly connected domains during operation while not impeding rotation is unknown. Remarkably, all known ATPase rotor rings are filled by lipids. In the crystal structure of the rotor ring of a V-ATPase from Enterococcus hirae the ring filling lipids form a proper membrane that is lower with respect to the embedding membrane surrounding both subunits. I propose first, that a vertical shift between lumenal lipids and embedding outside membrane is a general feature of rotor rings and second that it leads to a radial potential fall-off between rotor ring and cation channel, creating attractive forces that impact rotor-stator interaction in Fo/Vo/Ao during rotation.

No MeSH data available.