scholarly journals ATP synthesis catalyzed by a V-ATPase: an alternative pathway for energy conservation operating in plant vacuoles?

2008 ◽  
Vol 14 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Arnoldo Rocha Façanha ◽  
Anna Lvovna Okorokova-Façanha
Keyword(s):  
Energy Conservation ◽  
Alternative Pathway ◽  
Atp Synthesis ◽  
Plant Vacuoles

An Alternative Pathway of Adenylate and ATP Synthesis

1991 ◽  
pp. 285-288
Author(s):  
Celia Montero ◽  
Ryszard T. Smolenski ◽  
John A. Duley ◽  
H. Anne Simmonds
Keyword(s):  
Alternative Pathway ◽  
Atp Synthesis

Energy Conservation in Metabolism: The Mechanisms of ATP Synthesis

2015 ◽  
pp. 185-221
Author(s):  
Andrea T. Da Poian ◽  
Miguel A. R. B. Castanho
Keyword(s):  
Energy Conservation ◽  
Atp Synthesis

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 Absence of a common intermediate pool among individual enzyme chains of the energy-conservation pathway in chloroplasts of Euglena gracilis

1970 ◽  
Vol 116 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Joseph S. Kahn
Keyword(s):  
Electron Transport ◽  
Kinetic Model ◽  
Energy Conservation ◽  
Electron Acceptor ◽  
Specific Inhibitor ◽  
Atp Synthesis ◽  
Low Light ◽  
Cytochrome C552 ◽  
Limited Degree ◽  
Individual Enzyme

Tri-n-butyltin chloride is a specific inhibitor that binds stoicheiometrically and irreversibly with the ATP-synthesizing sites of chloroplasts. Titration of Euglena chloroplasts with tri-n-butyltin chloride shows about six ATP-synthesizing sites per molecule of cytochrome c552 or per 380 molecules of chlorophyll. This system was used to study the possibility of linkage between individual enzyme chains of the energy-conservation pathway or the possible existence of a common pool of an intermediate in this pathway. The inhibition of ATP synthesis by tri-n-butyltin chloride at low rates of electron transport (low light-intensities, NADP+ or ferricyanide as electron acceptor) agrees with a kinetic model of two to four ATP-synthesizing sites per energy-conservation chain. At high rates of electron transport, however, the results occasionally agree with a model of 20 or more sites per chain. The results are interpreted as indicating the absence of a common intermediate pool, but the presence of a limited degree of linkage between individual chains. It also indicates the presence of two energy-conservation sites in these chloroplasts.

Energy Conservation in Metabolism: The Mechanisms of ATP Synthesis

2021 ◽  
pp. 301-362
Author(s):  
Andrea T. Da Poian ◽  
Miguel A. R. B. Castanho
Keyword(s):  
Energy Conservation ◽  
Atp Synthesis

scholarly journals Chemiosmotic Energy Conservation with Na+ as the Coupling Ion during Hydrogen-Dependent Caffeate Reduction by Acetobacterium woodii

2002 ◽  
Vol 184 (7) ◽  
pp. 1947-1951 ◽  
Author(s):  
Frank Imkamp ◽  
Volker Müller
Keyword(s):  
Membrane Potential ◽  
Energy Conservation ◽  
Molecular Hydrogen ◽  
Atp Synthesis ◽  
Cell Suspensions ◽  
Acetobacterium Woodii ◽  
Atpase Inhibitor

ABSTRACT Cell suspensions of Acetobacterium woodii prepared from cultures grown on fructose plus caffeate catalyzed caffeate reduction with electrons derived from molecular hydrogen. Hydrogen-dependent caffeate reduction was strictly Na+ dependent with a Km for Na+ of 0.38 mM; Li+ could substitute for Na+. The sodium ionophore ETH2120, but not protonophores, stimulated hydrogen-dependent caffeate reduction by 280%, indicating that caffeate reduction is coupled to the buildup of a membrane potential generated by primary Na+ extrusion. Caffeate reduction was coupled to the synthesis of ATP, and again, ATP synthesis coupled to hydrogen-dependent caffeate reduction was strictly Na+ dependent and abolished by ETH2120, but not by protonophores, indicating the involvement of a transmembrane Na+ gradient in ATP synthesis. The ATPase inhibitor N,N′-dicyclohexylcarbodiimide (DCCD) abolished ATP synthesis, and at the same time, hydrogen-dependent caffeate reduction was inhibited. This inhibition could be relieved by ETH2120. These experiments are fully compatible with a chemiosmotic mechanism of ATP synthesis with Na+ as the coupling ion during hydrogen-dependent caffeate reduction by A. woodii.

scholarly journals Methyl Sulfide Production by a Novel Carbon Monoxide Metabolism in Methanosarcina acetivorans

2007 ◽  
Vol 74 (2) ◽  
pp. 540-542 ◽  
Author(s):  
James J. Moran ◽  
Christopher H. House ◽  
Jennifer M. Vrentas ◽  
Katherine H. Freeman
Keyword(s):  
Carbon Monoxide ◽  
Energy Conservation ◽  
Electron Donor ◽  
Dimethyl Sulfide ◽  
Atp Synthesis ◽  
Sodium Ion ◽  
Methanosarcina Acetivorans ◽  
Methyl Sulfide ◽  
Ion Gradients ◽  
Sulfide Production

ABSTRACT We observed dimethyl sulfide and methanthiol production in pure incubations of the methanogen Methanosarcina acetivorans when carbon monoxide (CO) served as the only electron donor. Energy conservation likely uses sodium ion gradients for ATP synthesis. This novel metabolism permits utilization of CO by the methanogen, resulting in quantitative sulfide methylation.

Proteolytic processing of the amyloid-beta protein precursor of Alzheimer's disease

2002 ◽  
Vol 38 ◽  
pp. 37-49 ◽  
Author(s):  
Janelle Nunan ◽  
David H Small
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Beta ◽  
Alternative Pathway ◽  
Protein A ◽  
Proteolytic Processing ◽  
Gamma Secretase ◽  
Amyloid Beta Protein ◽  
Protein Precursor ◽  
Amyloid Beta Protein Precursor

The proteolytic processing of the amyloid-beta protein precursor plays a key role in the development of Alzheimer's disease. Cleavage of the amyloid-beta protein precursor may occur via two pathways, both of which involve the action of proteases called secretases. One pathway, involving beta- and gamma-secretase, liberates amyloid-beta protein, a protein associated with the neurodegeneration seen in Alzheimer's disease. The alternative pathway, involving alpha-secretase, precludes amyloid-beta protein formation. In this review, we describe the progress that has been made in identifying the secretases and their potential as therapeutic targets in the treatment or prevention of Alzheimer's disease.

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