The rates of onset of photophosphorylation and of the protonic electrochemical potential difference in bacterial chromatophores

Melandri, B. Andrea; Santis, Adelmo De; Venturoli, Giovanni; Melandri, A. Baccarini

doi:10.1016/0014-5793(78)80067-2

Cited by 27 publications

(12 citation statements)

References 15 publications

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“…Similar indications have come from related experiments with bacterial chromatophores (Baccarini Melandri et al, 1977;Casadio et al, 1978;Melandri et al, 1978;Petty & Jackson, 1979) and vesicles . Furthermore, direct coupling between oxiVol.…”

Section: Methodssupporting

confidence: 79%

“…Thus, changes in the respiration rate would be reflected in the ATP synthesis rate even when the magnitude of the accepted intermediate in oxidative phosphorylation, Ap, is not itself perturbed. Essentially the same conclusion has been drawn from studies on bacterial chromatophores (Baccarini Melandri et al, 1977;Casadio et al, 1978;Melandri et al, 1978) although Ap was measured by procedures, carotenoid band shift and 9-aminoacridine fluorescence, different from those used in the present work.…”

Section: Methodssupporting

confidence: 75%

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The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

Sorgato¹,

Branca²,

Ferguson³

1980

Biochemical Journal

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The problem of whether the rate of ATP synthesis is proportional to the magnitude of the protonmotive force has been studied in submitochondrial particles. It was found that the rate of ATP synthesis can decrease at constant protonmotive force and is more closely related to the rate of substrate oxidation.The chemiosmotic mechanism (Mitchell, 1966(Mitchell, , 1976 of energy coupling requires that there should be a defined relationship between the magnitude of a transmembrane electrochemical proton gradient (protonmotive force, Ap) and the extent to which processes driven by Ap (e.g. ATP synthesis) are displaced from equilibrium. In contrast, the statement of the chemiosmotic hypothesis (Mitchell, 1966(Mitchell, , 1976 makes no prediction as to the relationships between changes in the rates of either energy-yielding or energy-utilizing processes and the magnitude of Ap, yet knowledge of these relationships is important both for an overall understanding of oxidative phosphorylation (and other related processes) as well as for applying the

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Section: Methodssupporting

confidence: 79%

Section: Methodssupporting

confidence: 75%

The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

Sorgato¹,

Branca²,

Ferguson³

1980

Biochemical Journal

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“…In the hypothesis called 'localized chemiosmosis' [6], domains are assumed where H + ions do not freely equilibrate with the bulk phase and where a A,CH higher than in bulk phase is established (cf. also [5,7,28]). Conformational changes of the ATPase are required, in the alternating site model of Boyer [9], for the utilization of A&.…”

mentioning

confidence: 92%

“…JATP is abolished by antimycin or decreasing light intensity with only 20% depression of A,& [26]. In single turnover experiments JATp is abolished at still high d j H values [27,28]. In chloroplasts [I 1,291 the lag phase preceeding initiation of phosphorylation after illumination is not prolonged by permeant buffers when ApH is the driving force (cf.…”

mentioning

confidence: 99%

On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria

Zoratti

Pietrobon

Azzone

1982

European Journal of Biochemistry

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The relationship between rate of ATP synthesis, JATp, and value of the proton electrochemical gradient, A f i~ has been analyzed in intact mitochondria.Onset of phosphorylation causes a depression of AfiH of 1.5 kJ/mol. There is a close parallelism between inhibition of &rp and restoration of A i H to its state-4 value during titrations with oligomycin or atractyloside.Titrations The consistence of the present data with either a chemiosmotic model where AFH is the sole and obligatory intermediate for energy coupling, or models where there is a direct transfer of energy between the two pumps is discussed.In mitochondria, bacteria and chloroplasts, e-transfer and ATP hydrolysis occur through the operation of H + pumps, which create a H + electrochemical gradient, A~H , between outer medium and inner space [l]. ATP synthesis is generally thought to occur through a back-to-back coupling of the two H i pumps. The mechanism proposed by Mitchell [2,3], known as the chemiosmotic hypothesis, assumes that coupling between redox and ATP-driven H + pumps is achieved through a delocalized A,& between the bulk aqueous phases and involves a H'-catalyzed reaction at the active site of the ATPase.Other views, although recognizing the fundamental role of protons, differ principally with respect to the molecular mechanisms and to the role of bulk phase A j H . According to Williams [4] the protons are generated in membrane-controlled spaces, not in equilibrium with one another, and the energized protons are trapped locally to drive ATP synthesis. AfiH represents an energy storage rather than an intermediate in coupling [4,5]. In the hypothesis called 'localized chemiosmosis' [6], domains are assumed where H + ions do not freely equilibrate with the bulk phase and where a A,CH higher than in bulk phase is established (cf. also [5,7,28]). Conformational changes of the ATPase are required, in the alternating site model of Boyer [9], for the utilization of A&. However it is doubtful whether these changes are due to the establishment of A f i~ or to protein-protein interactions in the membrane. AfiH-independent mechanisms have also been proposed by others (e.g. [lo-121).ATP synthesis can be driven by an artificial bulk-phase AfiH gradient in mitochondria, submitochondrial particles, Abbreviutions. CF30PhzC(CN)2, carbonylcyanide p-fluoromethoxyphenylhydrazone; Ph3MeP+, triphenylmethylphosphonium; Mops, 4-morpholinepropanesulfonic acid: Ap5A, adenosine(5')pentaphospho-(5')adenosine; J,, electron flow; Ah, electron flow in static head (state 4).chloroplasts and liposomes inlaid with the ATPase sythase complex [13-171. This is compatible with the views that ATP synthesis may be due either exclusively to a H + current through a protonic pathway reaching the FI-active site or to AiH-induced conformational changes coordinated with H + translocation at different sites.If the bulk-phase A& is the sole intermediate coupling the two H + pumps, some quantitative relationship between the rate of ATP synthesis, JATp, and A& is expected. One predicti...

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“…The small amount of ATP synthesized in the dark (due to the adenylate kinase reaction) was subtracted. For the experiments reported in ) from Sigma (L9009) in the reaction mixture described above, and the luminescence was detected in real-time at room temperature essentially as described previously [35]. The assay mixture was illuminated by a halogen lamp (160 WAEm )2 light intensity, filtered through 1 cm water and two layers of 88 A Wratten filters) and different illumination times were determined by an electronic shutter controlled by a Uniblitz T132 Driver.…”

Section: Light-induced Atp Synthesismentioning

confidence: 99%

A point mutation in the ATP synthase of Rhodobacter capsulatus results in differential contributions of DeltapH and Deltaphi in driving the ATP synthesis reaction

Turina

Melandri

2002

Eur J Biochem

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The interface between the c-subunit oligomer and the a subunit in the F 0 sector of the ATP synthase is believed to form the core of the rotating motor powered by the protonic flow. Besides the essential cAsp61 and aArg210 residues (Escherichia coli numbering), a few other residues at this interface, although nonessential, show a high degree of conservation, among these aGlu219. The homologous residue aGlu210 in the ATP synthase of the photosynthetic bacterium Rhodobacter capsulatus has been substituted by a lysine. Inner membranes prepared from the mutant strain showed approximately half of the ATP synthesis activity when driven both by light and by acid-base transitions. As estimated with the ACMA assay, proton pumping rates in the inner membranes were also reduced to a similar extent in the mutant. The most striking impairment of ATP synthesis in the mutant, a decrease as low as 12 times as compared to the wild-type, was observed in the absence of a transmembrane electrical membrane potential (Du) at low transmembrane pH difference (DpH). Therefore, the mutation seems to affect both the mechanism responsible for coupling F 1 with proton translocation by F 0 , and the mechanism determining the relative contribution of DpH and Du in driving ATP synthesis.

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The rates of onset of photophosphorylation and of the protonic electrochemical potential difference in bacterial chromatophores

Cited by 27 publications

References 15 publications

The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria

A point mutation in the ATP synthase of Rhodobacter capsulatus results in differential contributions of DeltapH and Deltaphi in driving the ATP synthesis reaction

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The rates of onset of photophosphorylation and of the protonic electrochemical potential difference in bacterial chromatophores

Cited by 27 publications

References 15 publications

The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

The rate of ATP synthesis by submitochondrial particles can be independent of the magnitude of the protonmotive force

On the Relationship between Rate of ATP Synthesis and H+ Electrochemical Gradient in Rat‐Liver Mitochondria

A point mutation in the ATP synthase of Rhodobacter capsulatus results in differential contributions of DeltapH and Deltaphi in driving the ATP synthesis reaction

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On the Relationship between Rate of ATP Synthesis and H⁺ Electrochemical Gradient in Rat‐Liver Mitochondria