Drive ATP Synthesis Research Articles

Butylhydroxylamine inhibits H +-driven atp synthesis of the TF 1 · F O-ATPase incorporated into liposomes

Butylhydroxylamine inhibits H +-driven atp synthesis of the TF 1 · F O-ATPase incorporated into liposomes

ATP synthesis coupled to light-dependent non-cyclic electron flow in chromatophores of Rhodopseudomonas capsulata

Light-dependent non-cyclic electron transport in membranes from aerobic dark-grown cells of Rhodopseudomonas capsulata, i.e., light-induced oxygen uptake, is clearly linked to energy transduction. It is proposed that the open chain performing the electron transfer from exogenous donors such as 2,6-dichlorophenolindophenol (DCIP) or N, N, N′, N′-tetramethyl- p-phenylenediamine (TMPD) to oxygen includes cytochrome c 2, reaction centre bacteriochlorophyll, ubiquinone molecules and the alternate oxidase (cytochrome b-260). In contrast, cytochrome b-60 previously suggested to act at the branching point of the dual electron transport system of Rps. capsulata (Zannoni, D., Melandri, B.A. and Baccarini-Melandri, A. (1976) Biochim. Biophys. Acta 449, 386–400) does not appear to be essential for aerobic photophosphorylation. This conclusion is derived mainly from experiments with Rps. capsulata R126 chromatophores deficient in cytochrome b-60 photoreduction and electron transfer through the cytochrome b- c segment of the chain. Indeed, these mutant membranes present normal rates of light-induced oxygen consumption. Moreover, this activity is coupled to Δμ H + formation which in turn drives ATP synthesis.

The partial resolution and dye-mediated reconstitution of methanol oxidase activity inMethylophilus methylotrophus

Methylophilus methylotrophus is a methylotrophic bacterium which uses methanol as its preferred source of carbon and energy. In common with other methylotrophic bacteria it oxidises methanol to formaldehyde via a methanol dehydrogenase which contains a pyrrolo-quinoline quinone prosthetic group [1]. Subsequent electron transfer to oxygen occurs via an apparently relatively simple respiratory chain which is composed of one or more c-type cytochromes (c n a n d / o r cL) plus cytochrome oxidases o a n d / o r aa 3 [2-4]. The overall methanol oxidase system in M. methyl otrophus, as in other methylotrophs, has been shown to catalyse effective proton translocation [4-6] and hence to generate a protonmotive force which can subsequently drive ATP synthesis (M.J. Dawson and C.W. Jones, unpublished). This paper reports that the methanol dehydrogenase and a large proportion of the cytochrome c of M. methylotrophus is probably loosely bound to the periplasmic side of the respiratory membrane, whereas the cytochrome oxidases and the remainder of the cytochrome c are firmly membranebound. Methanol oxidase activity can be fully reconstituted from a mixture of periplasm and

Molecular geometry of cytochrome c and its peroxidase: a model for biological electron transfer.

Although the respiratory electron transport chain was discovered (or more accurately, rediscovered) by David Keilin in 1925, progress toward understanding its operation at the molecular level has been painfully slow. Compare, for example, how far we have come in characterizing the intimate details of the citric acid cycle during roughly the same time span. The reason for this state of affairs is well known: the machinery of the electron transport chain consists of an extraordinarily complicated array of membrane bound, multi-subunit protein-lipid structures that can be dissected only with great difficulty. I have seen estimates that more than 20 metalcontaining redox centres are involved. Much of this complexity must arise from the way in which the machinery conserves almost all of the energy released in the reduction of oxygen to water by causing ATP to be synthesized. It appears to be generally accepted now that this energy conservation is accomplished by coupling electron transport to proton translocation, so that protons are pumped across the mitochondria1 inner membrane, out of the mitochondrial interior, and that the resulting proton gradient then drives ATP synthesis at other membrane-bound ATPase sites. The one protein component of the electron transport chain that has been most thoroughly examined is cytochrome c, a small soluble electron carrier protein which accepts electrons one at a time from Complex I11 and delivers them to the terminal oxidase, Complex IV. The latter in turn, as the final step in the process, somehow transfers four electrons to a bound 0, molecule and releases two water molecules. While the function of the terminal oxidase sounds simple enough, evidently that function requires a large, complicated molecular assemblage. It has only recently been established, for example, that the mammalian oxidase, Complex IV, probably consists of 12 polypeptide chains containing four redox centres (Merle & Kadenbach, 1980). Although I shall not further discuss the electron transport chain itself, I have introduced my subject in this way to justify the more than five years of effort our laboratory has put into the X-ray crystallographic structure determination of an otherwise really rather obscure haem-containing enzyme, yeast cytochrome c peroxidase, which will be my main focus. What I shall be telling you about, essentially, is how the structure of cytochrome c peroxidase has suggested a working model for haem-catalysed reductive cleavage of the oxygen-xygen bond and electron transfer between protein-bound redox centres, both of which are central features of the respiratory electron transport chain. Details may be found in Poulos et al. (1978, 1980) and Poulos & Kraut (1980a,b). Cytochrome c peroxidase catalyses the oxidation of reduced cytochrome c by hydrogen peroxide and alkyl hydroperoxides, and let me admit at the outset that its biological function is still obscure. However, the enzyme is relatively small (293 amino acid residues), water soluble and readily crystallized. But most importantly, the cytochrome c peroxidase molecule may in certain respects provide clues as to how the terminal oxidase works and in particular how it interacts with cytochrome c. Thus, although we don't know why it's there, cytochrome c The Eighth Keilin Memorial Lecture

Effects of permeant buffers on the initial time course of photophosphorylation and postillumination phosphorylation.

Permeant buffers (pyridine, imidazole, or phosphate) caused similar increases in the time required for onset of ATP synthesis in the light in the presence of valinomycin and K+; and in the illumination time required for postillumination phosphorylation with or without or without valinomycin and K+. Based on prior evidence, the minimum illumination time required for postillumination phosphorylation in thylakoid membranes is taken as a measure of the time required for formation of a transmembrane pH gradient sufficient to drive ATP synthesis. Our results are consistent with the view that, following illumination, as the transient transmembrane electric gradient decays, the establishment and maintenance of a pH gradient serves for energy transfer from the photosystems to the ATP synthase complex.

Structure and function of H+-ATPase

(1) Extensive studies on proton-translocating ATPase (H+-ATPase) revealed that H+-ATPase is an energy transforming device universally distributed in membranes of almost all kinds of cells. (2) Crystallization of the catalytic portion (F1) of H+-ATPase showed that F1 is a hexagonal molecule with a central hole. The diameter of F1 is about 90 A and its molecular weight is about 380,000. (3) Use of thermophilic F1 permits the complete reconstitution of F1 from its five subunits (alpha, beta, gamma, delta, epsilon) and demonstration of the gate function of the gamma delta epsilon-complex, the catalytic function of beta (supported by alpha and gamma), and the H+-translocating functions of all five subunits. (4) Studies using purified thermostable F0 showed that F0 is an H+-channel portion of H+-ATPase. The direct measurement of H+-flux through F0, sequencing of DCCD-binding protein, and isolation of F1-binding protein are described. (5) The subunit stoichiometry of F1 may be alpha 3 beta 3 gamma delta epsilon. (6) Reconstitution of stable H+-ATPase-liposomes revealed that ATP is directly synthesized by the flow of H+ driven by an electrochemical potential gradient and that H+ is translocated by ATP hydrolysis. This rules out functions for all the hypothetical components that do not belong to H+-ATPase in H+-driven ATP synthesis. The roles of conformation change and other phenomena in ATP synthesis are also discussed.

Salt reversal of the acid-induced changes in purple membrane from halobacterium halobium

FEBS LettersVolume 95, Issue 1 p. 35-39 Full-length articleFree Access Salt reversal of the acid-induced changes in purple membrane from halobacterium halobium Mary E. Edgerton, Mary E. Edgerton School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ England Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this authorTerry A. Moore, Terry A. Moore Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this authorColin Greenwood, Colin Greenwood School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ England Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this author Mary E. Edgerton, Mary E. Edgerton School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ England Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this authorTerry A. Moore, Terry A. Moore Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this authorColin Greenwood, Colin Greenwood School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ England Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, EnglandSearch for more papers by this author First published: November 01, 1978 https://doi.org/10.1016/0014-5793(78)80046-5Citations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 D. Oesterhelt, W. Stoeckenius, Nature, 233, (1971), 149– 152. 2 J. Bridgen, I.D. Walker, Biochemistry, 5, (1976), 792– 798. 3 D. Oesterhelt, W. Stoeckenius, Proc. Natl. Acad. Sci. USA, 70, (1973), 2853– 2857. 4 E. Racker, W. Stoeckenius, J. Biol. Chem., 249, (1974), 662– 663. 5 R.H. Lozier, R.A. Bogolmolni, W. Stoeckenius, Biophys. J., 15, (1975), 955– 962. 6 K.F. Kaufman, P.M. Rentcepsis, W. Stoeckenius, A. Lewis, Biochem. Biophys. Res. Commun., 68, (1976), 1109– 1115. 7 W.V. Sherman, R. Korenstein, S.R. Caplan, Biochim. Biophys. Acta, 430, (1976), 454– 458. 8 R.H. Lozier, W. Niederberger, R.A. Bogolmolni, S.B. Hwang, W. Stoeckenius, Biochim. Biophys. Acta, 440, (1976), 545– 556. 9 T.A. Moore, M.E. Edgerton, G. Parr, C. Greenwood, R. Perham, Biochem. J., 171, (1978), 469– 476. 10 D. Oesterhelt, W. Stoeckenius, Methods Enzymol., 3A, (1974), 667– 668. 11 Q.H. Gibson, C. Greenwood, J. Biol. Chem., 240, (1965), 2694– 2698. 12 F.A. Cotton, G. Wilkinson, 2nd edn. Advanced Inorganic Chemistry (1966), Interscience Publishers New York 13 V.A. Vaver, D.C. Tosteson Membrane Transport Processes 2, (1977), Raven Press New York 14 A.G. Lee, Biochim. Biophys. Acta, 472, (1977), 273– 281. 15 A.G. Lee, Biochim. Biophys. Acta, 472, (1977), 285– 344. 16 M.B. Jackson, J.M. Sturlevant, Biochemistry, 17, (1978), 911– 915. 17 W.V. Sherman, S.R. Caplan, Biochim. Biophys. Acta, 502, (1978), 222– 231. Citing Literature Volume95, Issue1November 01, 1978Pages 35-39 ReferencesRelatedInformation

Proton electrochemical gradient and phosphate potential in mitochondria

The paper reports an analysis of the relationship between Δ \\ ̃ gm H the proton electrochemical potential difference, and ΔGp, the phosphate potential. Depression of Δ \\ ̃ gm H and ΔGp has been obtained by titration with: (a) carbonylcyanide trifluoromethoxyphenylhydrazone; (b) nigericin (+ valinomycin); (c) KCl (+ valinomycin); and (d) rotenone. The uncoupler depresses Δ \\ ̃ gm H more than nigericin (+ valinomycin), KCl (+ valinomycin) and rotenone at equivalent ΔGp. The ΔG p/Δ \\ ̃ gm H ratio is about 3 at high values of Δ \\ ̃ gm H . When ΔGp and Δ \\ ̃ gm H are depressed by nigericin (+ valinomycin) the ΔG p/Δ \\ ̃ gm H ratio remains constant. When ΔGp and Δ \\ ̃ gm H are depressed by uncouplers, the ΔG p/Δ \\ ̃ gm H ratio increases hyperbolically tending to infinity while Δ \\ ̃ gm H tends to zero. The absence of constant proportionality between ΔGp and Δ \\ ̃ gm H indicates that the proton gradients driving ATP synthesis presumably operate within microscopic environments.

A model for conformational coupling of membrane potential and proton translocation to ATP synthesis and to active transport

Acceptance of a membrane potential and/or a proton gradient as a possible means of transmitting energy from oxidations to ATP synthesis rests in part on a satisfactory hypothesis for how the potential or proton gradient could drive ATP synthesis. Recognition that energy input may drive ATP synthesis by change in binding of reactants at the catalytic site has led to the suggestions presented in this paper. These are that in oxidative phosphorylation and photophosphorylation, the requisite conformational changes may be coupled to exposure of charged groups to different sides of the membrane. The cycle of charged group exposure or movement may be driven by the membrane potential or, through protonation and deprotonation, may be coupled to proton translocation across the membrane. Effects of proton gradient and membrane potential may be additive. Similar conformational coupling suggestions may explain proton translocation coupled to ATP cleavage and active transport of metabolites coupled to membrane potential, proton gradients of ATP cleavage.

A protonmotive force drives ATP synthesis in bacteria.

When cells of Streptococcus lactis or Escherichia coli were suspended in a potassium-free medium, a membrane potential (negative inside) could be artificially generated by the addition of the potassium ionophore, valinomycin. In response to this inward directed protonmotive force, ATP synthesis catalyzed by the membrane-bound ATPase (EC 3.6.1.3) was observed. The formation of ATP was not found in S. lactis that had been treated with the ATPase inhibitor, N,N'-dicyclohexylcarbodiimide, nor was it observed in a mutant of E. coli lacking the ATPase. Inhibition of ATP synthesis in S. lactis was also observed when the membrane potential was reduced by the presence of external potassium, or when cells were first incubated with the proton conductor, carbonylcyanidefluoromethoxyphenylhydrazone. These results are in agreement with predictions made by the chemiosmotic hypothesis of Mitchell.

The polarity of proton translocation in some photosynthetic microorganisms.

Observations on the direction of proton translocation coupled to photo-oxidoreduction and to respiration show that in chromatophores (or sonic particles) of Rhodospirillum rubrum and Rhodopseudomonas spheroides the direction is inwards, but in the intact organisms the direction is outwards. The relative proton translocation activities associated with photo-oxidoreduction and respiration appear to depend on the relative extent of development of the alternative pigment systems produced during growth. The direction of proton translocation associated with the oligomycin-sensitive ATPase activity in chromatophores of R. rubrum was the same as that associated with photo-oxidoreduction or respiration, suggesting that the proton current generated either by light or by respiration might alternatively drive ATP synthesis. Proton translocation, associated with photo-oxidoreduction or respiration, is directed outwards in intact Anabaena variabilis.