Cation channels by subunit III of the channel portion of the chloroplast H<sup>+</sup>‐ATPase

Schönknecht, Gerald; Althoff, Gerd; Apley, Enno C.; Wagner, Richard; Junge, Wolfgang

doi:10.1016/0014-5793(89)81650-3

Cited by 20 publications

(8 citation statements)

References 25 publications

(18 reference statements)

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“…After removal of CF 1 from the liposomes by NaBr treatment, CF 0 was shown to display various kinds of channels that were also permeable to monovalent cations (Sconknecht et al 1989 ; Wagner et al 1989 ). The probability of the CF 0 -CF 1 channel being open increased considerably with increasing membrane voltage, but in the presence of ADP and Pi, this probability decreased and the channel was almost completely blocked (Wagner et al 1989 ).…”

Section: Comparison Of the Properties Of Ion Channels And Atp Synthasmentioning

confidence: 99%

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

Kasumov¹,

Kasumov²,

Kasumova³

2014

Photosynth Res

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ATP is synthesized using ATP synthase by utilizing energy either from the oxidation of organic compounds, or from light, via redox reactions (oxidative- or photo phosphorylation), in energy-transforming membranes of mitochondria, chloroplasts, and bacteria. ATP synthase undergoes several changes during its functioning. The generally accepted model for ATP synthesis is the well-known rotatory model (see e.g., Junge et al., Nature 459:364–370, 2009; Junge and Müller, Science 333:704–705, 2011). Here, we present an alternative modified model for the coupling of electron and proton transfer to ATP synthesis, which was initially developed by Albert Lester Lehninger (1917–1986). Details of the molecular mechanism of ATP synthesis are described here that involves cyclic low-amplitude shrinkage and swelling of mitochondria. A comparison of the well-known current model and the mechano-chemiosmotic model is also presented. Based on structural, and other data, we suggest that ATP synthase is a Ca2+/H+–K+ Cl−–pump–pore–enzyme complex, in which γ-subunit rotates 360° in steps of 30°, and 90° due to the binding of phosphate ions to positively charged amino acid residues in the N-terminal γ-subunit, while in the electric field. The coiled coil b2-subunits are suggested to act as ropes that are shortened by binding of phosphate ions to positively charged lysines or arginines; this process is suggested to pull the α3β3-hexamer to the membrane during the energization process. ATP is then synthesized during the reverse rotation of the γ-subunit by destabilizing the phosphated N-terminal γ-subunit and b2-subunits under the influence of Ca2+ ions, which are pumped over from storage—intermembrane space into the matrix, during swelling of intermembrane space. In the process of ATP synthesis, energy is first, predominantly, used in the delivery of phosphate ions and protons to the α3β3-hexamer against the energy barrier with the help of C-terminal alpha-helix of γ-subunit that acts as a lift; then, in the formation of phosphoryl group; and lastly, in the release of ATP molecules from the active center of the enzyme and the loading of ADP. We are aware that our model is not an accepted model for ATP synthesis, but it is presented here for further examination and test.

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Section: Comparison Of the Properties Of Ion Channels And Atp Synthasmentioning

confidence: 99%

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

Kasumov¹,

Kasumov²,

Kasumova³

2014

Photosynth Res

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“…The authors attributed this voltage-gated conductance to the proton (Wagner et al, 1989). Whether this attribution was correct has remained an open question, in particular because proteoliposomes, which contained the purified c-subunit alone, have revealed unspecific cation channels (Schönknecht et al, 1989; for the proton conduction at pH 2 of the purified c-subunit see Schindler and Nelson, 1982).…”

Section: Introductionmentioning

confidence: 99%

The Proton-Driven Rotor of ATP Synthase: Ohmic Conductance (10 fS), and Absence of Voltage Gating

Feniouk

Kozlova

Knorre

et al. 2004

Biophysical Journal

105

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The membrane portion of F(0)F(1)-ATP synthase, F(0), translocates protons by a rotary mechanism. Proton conduction by F(0) was studied in chromatophores of the photosynthetic bacterium Rhodobacter capsulatus. The discharge of a light-induced voltage jump was monitored by electrochromic absorption transients to yield the unitary conductance of F(0). The current-voltage relationship of F(0) was linear from 7 to 70 mV. The current was extremely proton-specific (>10(7)) and varied only slightly ( approximately threefold) from pH 6 to 10. The maximum conductance was approximately 10 fS at pH 8, equivalent to 6240 H(+) s(-1) at 100-mV driving force, which is an order-of-magnitude greater than of coupled F(0)F(1). There was no voltage-gating of F(0) even at low voltage, and proton translocation could be driven by deltapH alone, without voltage. The reported voltage gating in F(0)F(1) is thus attributable to the interaction of F(0) with F(1) but not to F(0) proper. We simulated proton conduction by a minimal rotary model including the rotating c-ring and two relay groups mediating proton exchange between the ring and the respective membrane surface. The data fit attributed pK values of approximately 6 and approximately 10 to these relays, and placed them close to the membrane/electrolyte interface.

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“…Alternatively, the plant channel protein may be more vulnerable than its animal analogue and be denaturized during the purification procedure. Dehydration–rehydration procedure by itself, in turn, was proved in some cases to cause a disintegration of multimeric membrane proteins, causing alterations in ion transport properties (Schönknecht et al 1989). Further refinement of the preparation procedures could be a solution.…”

Section: Discussionmentioning

confidence: 99%

Patch clamp characterization of a non‐selective cation channel of ER membranes purified from Beta vulgaris taproots

Brito‐Argáez

Canto-Canché

Hernández‐Sotomayor

et al. 2008

Physiologia Plantarum

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The ER fraction from red beet taproot was purified on sucrose gradient and giant liposomes, suitable for patch clamping, were formed by dehydration-rehydration of the lipid film. Single-channel recordings on excised and attached patches revealed a large conductance (165 pS) cation (P(Cl-)/P(K+) < 0.03) channel with equal conductance and relative permeability for Na+ and K+. This non-selective cation channel was also highly permeable for Ca2+. We failed to detect any single-channel currents activated by a direct application of d-myo-inositol 1,4,5 trisphosphate, despite the fact that the ER membranes were native.

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Cation channels by subunit III of the channel portion of the chloroplast H⁺‐ATPase

Cited by 20 publications

References 25 publications

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

The Proton-Driven Rotor of ATP Synthase: Ohmic Conductance (10 fS), and Absence of Voltage Gating

Patch clamp characterization of a non‐selective cation channel of ER membranes purified from Beta vulgaris taproots

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Cation channels by subunit III of the channel portion of the chloroplast H+‐ATPase

Cited by 20 publications

References 25 publications

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

A mechano-chemiosmotic model for the coupling of electron and proton transfer to ATP synthesis in energy-transforming membranes: a personal perspective

The Proton-Driven Rotor of ATP Synthase: Ohmic Conductance (10 fS), and Absence of Voltage Gating

Patch clamp characterization of a non‐selective cation channel of ER membranes purified from Beta vulgaris taproots

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Cation channels by subunit III of the channel portion of the chloroplast H⁺‐ATPase