Photophosphorylation in Chloroplasts With Varied Proton Motive Force (PMF): II. Phosphorylation and the PMF

1982 ◽  
Vol 9 (4) ◽  
pp. 399 ◽  
Author(s):  
AB Hope ◽  
D Ranson ◽  
PG Dixon
Keyword(s):  
Time Lag ◽  
Atp Synthesis ◽  
Close Correlation ◽  
Proton Motive Force ◽  
Motive Force ◽  
Luciferase Assay ◽  
Time Lags ◽  
Constant Rate ◽  
Phosphorylation Reaction ◽  
The Mean

Measurements of ATP (luciferase assay) formed by class C pea chloroplasts in illumination times varying from 10 ms to 30 s are reported for control, + valinomycin and + nigericin conditions. ATP was made at a constant rate in controls following a time lag of a few milliseconds which varied with the illumination. Valinomycin increased the time lag to ~100 ms after which therate approached controls. Nigericin caused a gradual decrease in rate of ATP synthesis over a period of ~1s . In the steady state the rate was a different function of the transthylakoid pH difference (ΔpH) with nigericin and with valinomycin, with thresholds at ΔpH = 2.9 and 3.5 respectively. The time lags and thresholds are shown to be consistent with a threshold proton motive force (PMF) of 140-190 mV in various experiments. It is argued that this PMF corresponds to that required to poise the phosphorylation reaction to the point of ATP net synthesis at the prevailing dark phosphorylation potential. The experiments could not decide between a stoichiometry of 2 or 3 protons per ATP. Data suitable for use in constructing a kinetic model are briefly discussed. The findings generally are interpreted as showing a close correlation between phosphorylation and the PMF estimated as the mean potential energy of protons in the intrathylakoid spaces relative to the outside. It is concluded that Mitchellian coupling between bulk protons and the ATP synthetase is not yet to be discarded.

scholarly journals The Rnf Complex of Clostridium ljungdahlii Is a Proton-Translocating Ferredoxin:NAD+ Oxidoreductase Essential for Autotrophic Growth

mBio ◽  
2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Pier-Luc Tremblay ◽  
Tian Zhang ◽  
Shabir A. Dar ◽  
Ching Leang ◽  
Derek R. Lovley
Keyword(s):  
Energy Conservation ◽  
Atp Synthesis ◽  
Proton Motive Force ◽  
Motive Force ◽  
Proton Gradient ◽  
Heterotrophic Growth ◽  
Deficient Mutant ◽  
Autotrophic Growth ◽  
Content Type ◽  
Clostridium Ljungdahlii

ABSTRACTIt has been predicted that the Rnf complex ofClostridium ljungdahliiis a proton-translocating ferredoxin:NAD+oxidoreductase which contributes to ATP synthesis by an H+-translocating ATPase under both autotrophic and heterotrophic growth conditions. The recent development of methods for genetic manipulation ofC. ljungdahliimade it possible to evaluate the possible role of the Rnf complex in energy conservation. Disruption of theC. ljungdahlii rnfoperon inhibited autotrophic growth. ATP synthesis, proton gradient, membrane potential, and proton motive force collapsed in the Rnf-deficient mutant with H2as the electron source and CO2as the electron acceptor. Heterotrophic growth was hindered in the absence of a functional Rnf complex, as ATP synthesis, proton gradient, and proton motive force were significantly reduced with fructose as the electron donor. Growth of the Rnf-deficient mutant was also inhibited when no source of fixed nitrogen was provided. These results demonstrate that the Rnf complex ofC. ljungdahliiis responsible for translocation of protons across the membrane to elicit energy conservation during acetogenesis and is a multifunctional device also implicated in nitrogen fixation.IMPORTANCEMechanisms for energy conservation in the acetogenClostridium ljungdahliiare of interest because of its potential value as a chassis for the production of biocommodities with novel electron donors such as carbon monoxide, syngas, and electrons derived from electrodes. Characterizing the components implicated in the chemiosmotic ATP synthesis during acetogenesis byC. ljungdahliiis a prerequisite for the development of highly productive strains. The Rnf complex has been considered the prime candidate to be the pump responsible for the formation of an ion gradient coupled with ATP synthesis in multiple acetogens. However, experimental evidence for a proton-pumping Rnf complex has been lacking. This study establishes theC. ljungdahliiRnf complex as a proton-translocating ferredoxin:NAD+oxidoreductase and demonstrates thatC. ljungdahliihas the potential of becoming a model organism to study proton translocation, electron transport, and other functions of the Rnf complex in energy conservation or other processes.

scholarly journals Pyrazinoic Acid Decreases the Proton Motive Force, Respiratory ATP Synthesis Activity, and Cellular ATP Levels

2011 ◽  
Vol 55 (11) ◽  
pp. 5354-5357 ◽  
Author(s):  
Ping Lu ◽  
Anna C. Haagsma ◽  
Hoang Pham ◽  
Janneke J. Maaskant ◽  
Selena Mol ◽  
...  
Keyword(s):  
Active Form ◽  
Atp Synthesis ◽  
Proton Motive Force ◽  
Motive Force ◽  
Antituberculosis Drug ◽  
First Line ◽  
Content Type ◽  
Atp Levels ◽  
Synthesis Activity ◽  
Pyrazinoic Acid

ABSTRACTPyrazinoic acid, the active form of the first-line antituberculosis drug pyrazinamide, decreased the proton motive force and respiratory ATP synthesis rates in subcellular mycobacterial membrane assays. Pyrazinoic acid also significantly lowered cellular ATP levels inMycobacterium bovisBCG. These results indicate that the predominant mechanism of killing by this drug may operate by depletion of cellular ATP reserves.

scholarly journals Mean velocities measured with the double pulse technique

2004 ◽  
Vol 22 (10) ◽  
pp. 3531-3536 ◽  
Author(s):  
E. Nielsen
Keyword(s):  
Theoretical Prediction ◽  
Measurement Technique ◽  
Time Lag ◽  
Pulse Velocity ◽  
Small Time ◽  
Double Pulse ◽  
Time Lags ◽  
Pulse Technique ◽  
The Mean ◽  
Pulse Measurements

Abstract. It was recently observed that double-pulse measurements of the mean velocities of a wide asymmetric spectrum are a function of the time lag between the pulses (Uspensky et al., 2004). Here we demonstrate that the observed relationship probably is influenced by the measurement technique in a way that is consistent with theoretical prediction. It is further shown that for small time lags the double pulse velocity is a good approximation to the mean Doppler velo-city.

scholarly journals Respiration of Escherichia coli Can Be Fully Uncoupled via the Nonelectrogenic Terminal Cytochrome bd-II Oxidase

2009 ◽  
Vol 191 (17) ◽  
pp. 5510-5517 ◽  
Author(s):  
M. Bekker ◽  
S. de Vries ◽  
A. Ter Beek ◽  
K. J. Hellingwerf ◽  
M. J. Teixeira de Mattos
Keyword(s):  
Escherichia Coli ◽  
Respiratory Chain ◽  
Electron Flux ◽  
Atp Synthesis ◽  
Proton Motive Force ◽  
Proton Pumping ◽  
Motive Force ◽  
Fixed Amount ◽  
Terminal Oxidases ◽  
Genes Encoding

ABSTRACT The respiratory chain of Escherichia coli is usually considered a device to conserve energy via the generation of a proton motive force, which subsequently may drive ATP synthesis by the ATP synthetase. It is known that in this system a fixed amount of ATP per oxygen molecule reduced (P/O ratio) is not synthesized due to alternative NADH dehydrogenases and terminal oxidases with different proton pumping stoichiometries. Here we show that P/O ratios can vary much more than previously thought. First, we show that in wild-type E. coli cytochrome bo, cytochrome bd-I, and cytochrome bd-II are the major terminal oxidases; deletion of all of the genes encoding these enzymes results in a fermentative phenotype in the presence of oxygen. Second, we provide evidence that the electron flux through cytochrome bd-II oxidase is significant but does not contribute to the generation of a proton motive force. The kinetics support the view that this system is as an energy-independent system gives the cell metabolic flexibility by uncoupling catabolism from ATP synthesis under non-steady-state conditions. The nonelectrogenic nature of cytochrome bd-II oxidase implies that the respiratory chain can function in a fully uncoupled mode such that ATP synthesis occurs solely by substrate level phosphorylation. As a consequence, the yield with a carbon and energy source can vary five- to sevenfold depending on the electron flux distribution in the respiratory chain. A full understanding and control of this distribution open new avenues for optimization of biotechnological processes.

scholarly journals Mitochondrial F1FO ATP synthase determines the local proton motive force in cristae tips

2021 ◽  
Author(s):  
Bettina Rieger ◽  
Tasnim Arroum ◽  
Jimmy Villalta ◽  
Karin B. Busch
Keyword(s):  
Atp Synthase ◽  
Mammalian Cells ◽  
Atp Hydrolysis ◽  
Ph Sensor ◽  
Atp Synthesis ◽  
Proton Motive Force ◽  
Motive Force ◽  
List Type ◽  
Inner Mitochondrial Membrane ◽  
Respiratory Chain Complexes

ABSTRACTThe classical view of oxidative phosphorylation is that a proton motive force PMF generated by the respiratory chain complexes fuels ATP synthesis. Under glycolytic conditions, ATP synthase in its reverse mode also can contribute to the PMF. Here, we dissected the two functions of ATP synthase and the role of its inhibitory factor 1 (IF1) under different metabolic conditions in detail. pH profiles of mitochondrial sub-compartments were recorded with high spatial resolution in live mammalian cells by positioning a pH-sensor directly at F1 and FO of ATP synthase, complex IV and in the matrix. Our results clearly show that ATP synthase activity is substantially controlling the PMF and that IF1 is essential under OXPHOS conditions to prevent reverse ATP synthase activity due to an almost negligible ΔpH.GRAPHICAL ABSTRACTHIGHLIGHTSThe ΔpH along and across the inner mitochondrial membrane is not homogeneousThe proton motive force at cristae tips is controlled by F1 FO ATP synthaseUnder OXPHOS conditions, the pH difference between FO and F1 of active ATP synthase is almost negligible (1.2 proton vs. 1 proton equivalent)IF1 is required to prevent the onset of ATP hydrolysis under OXPHOS conditions

Sign in / Sign up

Export Citation Format

Share Document