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Palmgren M, Morsomme P. The plasma membrane H + -ATPase, a simple polypeptide with a long history. Yeast 2018; 36:201-210. [PMID: 30447028 PMCID: PMC6590192 DOI: 10.1002/yea.3365] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 11/08/2018] [Accepted: 11/11/2018] [Indexed: 11/11/2022] Open
Abstract
The plasma membrane H+ -ATPase of fungi and plants is a single polypeptide of fewer than 1,000 residues that extrudes protons from the cell against a large electric and concentration gradient. The minimalist structure of this nanomachine is in stark contrast to that of the large multi-subunit FO F1 ATPase of mitochondria, which is also a proton pump, but under physiological conditions runs in the reverse direction to act as an ATP synthase. The plasma membrane H+ -ATPase is a P-type ATPase, defined by having an obligatory phosphorylated reaction cycle intermediate, like cation pumps of animal membranes, and thus, this pump has a completely different mechanism to that of FO F1 ATPases, which operates by rotary catalysis. The work that led to these insights in plasma membrane H+ -ATPases of fungi and plants has a long history, which is briefly summarized in this review.
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Affiliation(s)
- Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Pierre Morsomme
- Louvain Institute of Biomolecular Science and Technology (LIBST), UCLouvain, Louvain-la-Neuve, Belgium
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2
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Mildvan AS, Fry DC. NMR studies of the mechanism of enzyme action. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 59:241-313. [PMID: 3544711 DOI: 10.1002/9780470123058.ch6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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3
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Inesi G, Zhang Z, Lewis D. Cooperative setting for long-range linkage of Ca(2+) binding and ATP synthesis in the Ca(2+) ATPase. Biophys J 2002; 83:2327-32. [PMID: 12414670 PMCID: PMC1302322 DOI: 10.1016/s0006-3495(02)75247-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High-affinity and cooperative binding of two Ca(2+) per ATPase (SERCA) occurs within the membrane-bound region of the enzyme. Direct measurements of binding at various Ca(2+) concentrations demonstrate that site-directed mutations within this region interfere selectively with Ca(2+) occupancy of either one or both binding sites and with the cooperative character of the binding isotherms. A transition associated with high affinity and cooperative binding of the second Ca(2+) and the engagement of N796 and E309 are both required to form a phosphoenzyme intermediate with ATP in the forward direction of the cycle and also to form ATP from phosphoenzyme intermediate and ADP in the reverse direction of the cycle. This transition, defined by equilibrium and kinetic characterization of the partial reactions of the enzyme cycle, extends from transmembrane helices to the catalytic site through a long-range linkage and is the mechanistic device for interconversion of binding and phosphorylation potentials.
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Affiliation(s)
- Giuseppe Inesi
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201, USA.
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4
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Mitchell P. Bacterial flagellar motors and osmoelectric molecular rotation by an axially transmembrane well and turnstile mechanism. FEBS Lett 2001. [DOI: 10.1016/0014-5793(84)81182-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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5
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Abstract
Lactic acid is the major end-product of glycolysis by Streptococcus mutans under conditions of sugar excess or low environmental pH. However, the mechanism of lactic acid excretion by S. mutans is unknown. To characterize lactic acid efflux in S. mutans the transmembrane movement of radiolabelled lactate was monitored in de-energized cells. Lactate was found to equilibrate across the membrane in accordance with artificially imposed transmembrane pH gradient (Δψ). The imposition of a transmembrane electrical potential (Δψ) upon de-energized cells did not cause an accumulation of lactate within the cell. The efflux of lactate from lactate-loaded, deenergized cells created a ΔpH, but did not create a Δψ, indicating that lactate crosses the cell membrane in an electroneutral process, as lactic acid. ΔpH and Δψ were determined by the transmembrane equilibration of [14C]benzoic acid and [14C]tetraphenylphosphonium ion (TPP), respectively. The presence of a membrane carrier for lactic acid in S. mutans was suggested by counterflow. Enzymic determination of the intra- and extracellular lactate concentrations of S. mutans cells glycolysing at pHo 6.8 and 5.5 showed that lactate distributed across the cell membrane in accordance with the equation ΔpH = log[lact]i/[lact]o. The addition of high extracellular concentrations of lactate to glycolysing S. mutans at acidic pH resulted in a fall in ΔpH and a subsequent decrease in glycolysis. The fall in ΔpH was attributed to the F1F0 ATPase being unable to raise the pHi back to its initial level due to the build up of lactate anion within the cell creating a large Δψ. The increase in Δψ resulted in the overall proton motive force remaining constant at about −110 mV. The results demonstrate that lactate is transported across the cell membrane of S. mutans as lactic acid in an electroneutral process that is independent of metabolic energy and as such has important bioenergetic implications for the cell.
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Affiliation(s)
- Stuart G. Dashper
- Biochemistry and Molecular Biology Unit, School of Dental Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 711 Elizabeth Street, Melbourne, Victoria 3000, Australia
| | - Eric C. Reynolds
- Biochemistry and Molecular Biology Unit, School of Dental Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 711 Elizabeth Street, Melbourne, Victoria 3000, Australia
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6
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Repke KR, Schön R. Synthesis of a self-contained concept of the molecular mechanism of energy interconversion by H(+)-transporting ATP synthase. Biol Rev Camb Philos Soc 1994; 69:119-45. [PMID: 8054442 DOI: 10.1111/j.1469-185x.1994.tb01503.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The original aim of the review has been to probe into the validity of the paradigm on the high energy-carrier function of ATP. It seemed to be called into question on the basis of findings with H(+)-transporting ATP synthase suggesting the formation of ATP from ADP and Pi without energy input. Thus, ATP appeared as a low-energy compound. Starting from the current, rich knowledge of the molecular structure and the inviting thinking on the mechanism of H(+)-transporting ATP synthase, we have endeavoured to freshly interpret and integrate the pertinent observations in the light of the comprehensively derived model of the molecular mechanism of energy interconversion by Na+/K(+)-transporting ATPase. In this way, we have uncovered the common mechanistic elements of the two energy-interconverting enzymes. The emerging purpose of the present paper has been the 'synthesis' of a self-contained concept of the molecular mechanism of the interconversion of electrochemical and chemical Gibbs energies by H(+)-transporting ATP synthase. The outcome is reflected in the following tentative evaluations. 1. In ATP hydrolysis, the great Gibbs energy change which is observed in solution, is largely conserved by the F1 sector of ATP synthase as mechanical Gibbs energy in the enzyme's protein fabric, so that it can be utilized in the resynthesis of ATP from enzyme-bound ADP and Pi. The plainly measured low Gibbs energy change results from large compensating enthalpy and entropy changes that reflect the underlying changes in protein conformation. 2. In stoichiometric ATP synthesis by F1 sector from ADP and Pi bound to the catalytic centre, their intrinsic binding energy brings about a loss of peptide chain entropy that makes possible an entropy-driven ATP formation. 3. The driving force for ATP synthesis cannot be the high Gibbs energy change on binding of product ATP; the tight ATP-enzyme complex rather is a low Gibbs energy intermediate from which escape is difficult. 4. The catalytic centre exists either in an open state unable to firmly bind the substrate-product couple, or in a closed state protecting formed ATP from facile hydrolysis by ambient water. 5. The cleft closure, induced by binding of Pi and ADP or ATP, does not necessarily need external energy supply, because the cleft closure proceeds from rigid domain rotations which can occur rather spontaneously. In further analogy to adenylate kinase, the driving force of this domain movement presumably comes from the electrostatic interactions between phosphate moieties and arginine side chains in the catalytic centre.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K R Repke
- Energy Conversion Unit, Max Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany
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7
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Lin J, Addison R. Topology of the Neurospora plasma membrane H(+)-ATPase. Localization of a transmembrane segment. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41943-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Repke KR, Schön R. Chemistry and energetics of transphosphorylations in the mechanism of Na+/K(+)-transporting ATPase: an attempt at a unifying model. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1154:1-16. [PMID: 8389589 DOI: 10.1016/0304-4157(93)90014-f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- K R Repke
- Energy Conversion Unit, Max Delbrück Centre for Molecular Medicine, Berlin-Buch, Germany
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9
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Satoh K, Nagai F, Ushiyama K, Yasuda I, Akiyama K, Kano I. Inhibition of Na+,K(+)-ATPase activity by beta-eudesmol, a major component of atractylodis lanceae rhizoma, due to the interaction with enzyme in the Na.E1 state. Biochem Pharmacol 1992; 44:373-8. [PMID: 1322667 DOI: 10.1016/0006-2952(92)90022-b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
beta-Eudesmol, a major component of the crude drug "So-jutsu" (Atractylodis Lanceae Rhizoma), inhibited Na+, K(+)-ATPase activity most strongly among the various kinds of phosphatases examined. It also inhibited Ca(2+)-ATPase and H+, K(+)-ATPase, but to a lesser extent. Its effect on Mg(2+)-ATPase was minute. No effects on H(+)-ATPase or alkaline and acid phosphatase activities were observed. The effects of beta-eudesmol on horse kidney Na+, K(+)-ATPase were studied in detail, and the following results were obtained: (1) beta-eudesmol inhibited the Na+, K(+)-ATPase activity with an I50 value of 1.6 x 10(-4) M. The mode of its inhibition was uncompetitive with respect to ATP; (2) it prevented the stimulation of enzyme activity by Na+. The inhibition gradually increased in accord with the increase of Na+ concentration, and it was constant when Na+ was higher than 6.3 mM; (3) it did not alter the K+ concentration necessary for half-maximal activation (K0.5 for K+); and (4) it inhibited the enzyme activity with a mode of action different from ouabain. Phosphorylation of enzyme with [gamma-32P]ATP was inhibited by beta-eudesmol with an I50 of 1.4 x 10(-4) M. The inhibition was greater in 1 M NaCl than in 0.1 M NaCl. It had no effects on dephosphorylation steps, i.e. none of the non-specific, the ADP-sensitive (Na.E1-P----Na.E1) and the K(+)-dependent (E2-P----K.E2) dephosphorylation processes were affected. These results suggest that beta-eudesmol, a relatively specific inhibitor of Na+, K(+)-ATPase, interacts with the enzyme in the Na.E1 form and inhibits the reaction step Na.E1----Na.E1-P.
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Affiliation(s)
- K Satoh
- Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Japan
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10
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Repke KR, Schön R. Role of protein conformation changes and transphosphorylations in the function of Na+/K(+)-transporting adenosine triphosphatase: an attempt at an integration into the Na+/K+ pump mechanism. Biol Rev Camb Philos Soc 1992; 67:31-78. [PMID: 1318758 DOI: 10.1111/j.1469-185x.1992.tb01658.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The particular aim of the review on some basic facets of the mechanism of Na+/K(+)-transporting ATPase (Na/K-ATPase) has been to integrate the experimental findings concerning the Na(+)- and K(+)-elicited protein conformation changes and transphosphorylations into the perspective of an allosterically regulated, phosphoryl energy transferring enzyme. This has led the authors to the following summarizing evaluations. 1. The currently dominating hypothesis on a link between protein conformation changes ('E1 in equilibrium with E2') and Na+/K+ transport (the 'Albers-Post scheme') has been constructed from a variety of partial reactions and elementary steps, which, however, do not all unequivocally support the hypothesis. 2. The Na(+)- and K(+)-elicited protein conformation changes are inducible by a variety of other ligands and modulatory factors and therefore cannot be accepted as evidence for their direct participation in effecting cation translocation. 3. There is no evidence that the 'E1 in equilibrium with E2' protein conformation changes are moving Na+ and K+ across the plasma membrane. 4. The allosterically caused ER in equilibrium with ET ('E1 in equilibrium with E2') conformer transitions and the associated cation 'occlusion' in equilibrium with 'de-occlusion' processes regulate the actual catalytic power of an enzyme ensemble. 5. A host of experimental variables determines the proportion of functionally competent ER enzyme conformers and incompetent ET conformers so that any enzyme population, even at the start of a reaction, consists of an unknown mixture of these conformers. These circumstances account for the occurrence of contradictory observations and apparent failures in their comparability. 6. The modelling of the mechanism of the Na/K-ATPase and Na+/K+ pump from the results of reductionistically designed experiments requires the careful consideration of the physiological boundary conditions. 7. Na+ and K+ ligandation of Na/K-ATPase controls the geometry and chemical reactivity of the catalytic centre in the cycle of E1 in equilibrium with E2 state conversions. This is possibly effected by hinge-bending, concerted motions of three adjacent, intracellularly exposed peptide sequences, which shape open and closed forms of the catalytic centre in lock-and-key responses. 8. The Na(+)-dependent enzyme phosphorylation with ATP and the K(+)-dependent hydrolysis of the phosphoenzyme formed are integral steps in the transport mechanism of Na/K-ATPase, but the translocations of Na+ and K+ do not occur via a phosphate-cation symport mechanism.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K R Repke
- Energy Conversion Unit, Central Institute of Molecular Biology, Berlin-Buch, Germany
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11
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Martonosi AN, Jona I, Molnar E, Seidler NW, Buchet R, Varga S. Emerging views on the structure and dynamics of the Ca2(+)-ATPase in sarcoplasmic reticulum. FEBS Lett 1990; 268:365-70. [PMID: 2143486 DOI: 10.1016/0014-5793(90)81287-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The ATP-dependent Ca2+ transport in sarcoplasmic reticulum involves transitions between several structural states of the Ca2(+)-ATPase, that occur without major changes in the secondary structure. The rates of these transitions are modulated by the lipid environment and by interactions between ATPase molecules. Although the Ca2(+)-ATPase restricts the rotational mobility of a population of lipids, there is no evidence for specific interaction of the Ca2(+)-ATPase with phospholipids. Fluorescence polarization and energy transfer (FET) studies, using site specific fluorescent indicators, combined with crystallographic, immunological and chemical modification data, yielded a structural model of Ca2(+)-ATPase in which the binding sites of Ca2+ and ATP are tentatively identified. The temperature dependence of FET between fluorophores attached to different regions of the ATPase indicates the existence of 'rigid' and 'flexible' regions within the molecule characterized, by different degrees of thermally induced structural fluctuations.
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Affiliation(s)
- A N Martonosi
- Department of Biochemistry and Molecular Biology, State University of New York, Syracuse 13210
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12
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Apell HJ, Solioz M. Electrogenic transport by the Enterococcus hirae ATPase. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1017:221-8. [PMID: 2164846 DOI: 10.1016/0005-2728(90)90188-a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A transport ATPase from Enterococcus hirae was reconstituted in lipid vesicles and its electrogenic action investigated with the fluorescent dye oxonol VI as membrane potential probe. Reconstitution in bacterial and in soybean phospholipid mixtures led to transport-active vesicle preparations. Inside-out oriented ATPase molecules were activated by the addition of ATP to the extravesicular medium, generating in all experiments an intravesicularly positive potential. The extravesicular pH strongly influenced the initial pumping rate and the duration of the pumping activity. At neutral pH, transient pumping activity was observed, lasting for 1-2 min, while at pH 5.6, pumping was continuous. The transport activity was not dependent on the ionic composition of the buffer on either side of the membrane. These findings can be interpreted as the action of a proton ATPase, regulated by the cytoplasmic proton concentration and electrogenically translocating protons from the cytoplasm to the extracellular space.
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Affiliation(s)
- H J Apell
- Department of Biology, University of Konstanz, F.R.G
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13
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Affiliation(s)
- C L Slayman
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut 06510
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14
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Siebers A, Altendorf K. The K+-translocating Kdp-ATPase from Escherichia coli. Purification, enzymatic properties and production of complex- and subunit-specific antisera. EUROPEAN JOURNAL OF BIOCHEMISTRY 1988; 178:131-40. [PMID: 2849541 DOI: 10.1111/j.1432-1033.1988.tb14438.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The Kdp system from Escherichia coli is a derepressible high-affinity K+-uptake ATPase. Its membrane-bound ATPase activity was approximately 50 mumol g-1 min-1. The Kdp-ATPase complex was purified from everted vesicles by solubilization with the nonionic detergent Aminoxid WS 35 followed by DEAE-Sepharose CL-6B chromatography at pH 7.5 and pH 6.4 and gel filtration on Fractogel TSK HW-65. The overall yield of activity was 6.5% and the purity at least 90%. The isolated KdpABC complex had a high affinity for its substrates K+ (Km app. = 10 microM) and Mg2+-ATP (Km = 80 microM) and a narrow substrate specificity. The ATPase activity was inhibited by vanadate (Ki = 1.5 microM), fluorescein isothiocyanate (Ki = 3.5 microM), N,N'-dicyclohexylcarbodiimide (Ki = 60 microM) and N-ethylmaleimide (Ki = 0.1 mM). The purification protocol was likewise applicable to the isolation of a KdpA mutant ATPase which in contrast to the wild-type enzyme exhibited an increased Km value for K+ of 6 mM and a 10-fold lowered sensitivity for vanadate. Starting from the purified Kdp complex the single subunits were obtained by gel filtration on Bio-Gel P-100 in the presence of SDS. Both the native Kdp-ATPase and the SDS-denatured polypeptides were used to raise polyclonal antibodies. The specificity of the antisera was established by immunoblot analysis. In functional inhibition studies the anti-KdpABC and anti-KdpB sera impaired ATPase activity in the membrane-bound as well as in the purified state of the enzyme. In contrast, the anti-KdpC serum did not inhibit enzyme activity.
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Affiliation(s)
- A Siebers
- Universität Osnabrück, Federal Republic of Germany
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15
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Peschek G, Nitschmann W, Czerny T. [39] Respiratory proton extrusion and plasma membrane energization. Methods Enzymol 1988. [DOI: 10.1016/0076-6879(88)67042-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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16
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Secretory protein translocation in a neurospora crassa in vitro system. Hydrolysis of a nucleoside triphosphate is required for posttranslational translocation. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45487-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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17
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Cloning of the K+-ATPase of Streptococcus faecalis. Structural and evolutionary implications of its homology to the KdpB-protein of Escherichia coli. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)48244-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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18
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Ronjat M, Lacapere J, Dufour J, Dupont Y. Study of the nucleotide binding site of the yeast Schizosaccharomyces pombe plasma membrane H+-ATPase using formycin triphosphate-terbium complex. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61482-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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19
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Abstract
In a human, the cells function adequately to the needs of the organism, and to their own needs. Consequently, adequate cell function is comprised of the organism-oriented, and cell-oriented functions. It is suggested that an independent stage in the pathogenesis of a chronic disease exists which so far has not been considered. This is the disturbance of the cell-oriented function of the cells involved. This initial stage may last for years and decades, whereas function of the organ remains preserved. Organism-oriented cellular function appears to become involved in the pathologic process long after the disease has actually started. At this time the cells themselves are severely impaired, and as a result a disease acquires its progressive, irreversible course. Pathogenesis of atherosclerosis is considered as an example of the above-mentioned developments.
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20
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Scarborough GA. A chemically explicit model for the molecular mechanism of the F1F0 H+-ATPase/ATP synthases. Proc Natl Acad Sci U S A 1986; 83:3688-92. [PMID: 2872673 PMCID: PMC323588 DOI: 10.1073/pnas.83.11.3688] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A general hypothesis for the molecular mechanism of membrane transport based on current knowledge of protein structure and the nature of ligand-induced protein conformational changes has recently been proposed [Scarborough, G. A. (1985) Microbiol. Rev. 49, 214-231]. According to this hypothesis, the essential reaction undergone by all proteinaceous transport catalysts is a ligand-induced hinge-bending-type conformational change that results in the transposition of binding-site residues from access on one side of the membrane to access on the other side. Subsequent release and/or alteration of the ligand or ligands that induce the conformational change facilitates the converse conformational change, which returns the binding-site residues to their original position. With this simple cyclic ligand-dependent gating process as a central feature, biochemically orthodox mechanisms for virtually all known transporters are readily conceived. In this article, a chemically explicit model for the molecular mechanism of the F1F0 H+-ATPase/ATP synthases of mitochondria, bacteria, and chloroplasts, formulated within the guidelines of this general transport paradigm, is presented. At least three points of potential interest arise from this exercise. First, with the aid of the model, it is possible to visualize how energy transduction catalyzed by these enzymes might proceed, with no major events left unspecified. Second, explicit possibilities as to the molecular nature of electric field effects on the transport process are raised. And finally, it is shown that enzyme conformational changes, energy-dependent binding-affinity changes, and several other related phenomena as well, need not be taken as evidence of "action at a distance" or indirect energy coupling mechanisms, as is sometimes assumed, because such events are also integral features of the mechanism presented, even though all of the key reactions proposed for both ATP-driven proton translocation and proton translocation-driven ATP synthesis occur at the enzyme active site.
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21
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Transient-state kinetics of phosphoenzyme transformation in the rabbit skeletal sarcoplasmic reticulum calcium-dependent adenosine triphosphatase reaction. Two distinct modes of ADP and K+ regulation. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)84564-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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22
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Stein WD. Intrinsic, apparent, and effective affinities of co- and countertransport systems. THE AMERICAN JOURNAL OF PHYSIOLOGY 1986; 250:C523-33. [PMID: 3008563 DOI: 10.1152/ajpcell.1986.250.4.c523] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Solutions to kinetic schemes for the simple carrier, the countertransporter (antiport, exchanger), and the rapid equilibrium cases of the cotransporter (symport) and co-chemiporter (cation-dependent ATPase) are listed. A distinction is made between the intrinsic, apparent, and effective affinities of the transporters for their substrates. Effective pumping requires that the active transporter binds the pumped substrate, at high affinity, realized at the "whence side" (from which pumping takes place) and, at low affinity, at the "whither side" (to which pumping takes place). It is demonstrated how effective pumping might be achieved by appropriate design of the transporter or chemiporter in terms of the energies of the intrinsic binding sites, the energies of the conformation changes that the pump protein undergoes, the dissociation constant of the chemical reaction that drives the co-chemiport, and the order of binding of the cosubstrates, appropriate at different prevailing levels of the driving substrate.
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23
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Binding energy, conformational change, and the mechanism of transmembrane solute movements. Microbiol Rev 1985; 49:214-31. [PMID: 2413342 PMCID: PMC373034 DOI: 10.1128/mr.49.3.214-231.1985] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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24
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Muallem S, Schoeffield M, Pandol S, Sachs G. Inositol trisphosphate modification of ion transport in rough endoplasmic reticulum. Proc Natl Acad Sci U S A 1985; 82:4433-7. [PMID: 3874400 PMCID: PMC391115 DOI: 10.1073/pnas.82.13.4433] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The ion transport properties of the rough endoplasmic reticulum (RER) from liver have been defined by using measurements of active and potential gradient-driven transport. The Ca2+ pump is shown to be electrogenic, and both ATP and potential difference is able to drive vanadate-inhibitable Ca2+ uptake into the RER. ATP-dependent Ca2+ transport into the RER depends on the presence of tetraethylammonium-sensitive cation conductance and a furosemide-inhibited cation/chloride cotransport pathway. Inositol trisphosphate does not affect either of the monovalent ion translocation systems but activates a Ca2+ conductance in the RER, allowing efflux of RER Ca2+ stores into the cytosol in exchange for K+ uptake.
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25
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Abstract
The reversible protonmotive F0F1 ATPases perform the uniquely important function of balancing the forces, and interconverting the potential energies, of phosphoryl transfer and proton translocation. The molecular mechanics of the processes of ligand conduction catalysed by the F0F1 ATPases is therefore especially interesting. This paper summarises the main structural and functional knowledge of the F0F1 ATPases in the light of current mechanistic hypotheses, and suggests a new type of rotating subunit hypothesis, which is related to that recently developed for bacterial flagellar motors.
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26
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27
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Fürst P, Solioz M. Formation of a beta-aspartyl phosphate intermediate by the vanadate-sensitive ATPase of Streptococcus faecalis. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89690-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Amory A, Goffeau A, McIntosh DB, Boyer P. Contribution of 18O technology to the mechanism of the H+-ATPase from yeast plasma membrane. CURRENT TOPICS IN CELLULAR REGULATION 1984; 24:471-83. [PMID: 6238813 DOI: 10.1016/b978-0-12-152824-9.50047-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Tanford C. Twenty questions concerning the reaction cycle of the sarcoplasmic reticulum calcium pump. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1984; 17:123-51. [PMID: 6097403 DOI: 10.3109/10409238409113603] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The problem of "mechanism" for the calcium pump may be divided into three parts. (1) It is an enzyme catalyzing the hydrolysis of ATP. (2) At some stage of the reaction cycle it provides a pathway through the otherwise impermeable phospholipid bilayer. (3) The two properties are linked so as to provide exchange of free energy between the two substrates (ATP and Ca2+), without any exchange of matter. The third part is the most interesting, and the mechanistic problem it poses is common to all chemiosmotic free energy transducers. All three aspects of the mechanism are reviewed here, with special emphasis on the remaining experimental questions that need to be resolved. The review will show that even such fundamental questions as the exact stoichiometry of the catalyzed reaction have not yet received definitive answers.
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Abstract
The mechanism of free energy coupling in active transport is discussed with special reference to the sarcoplasmic reticulum Ca2+-ATPase. In the current working schemes for cation transport ATPases, free energy transduction is nearly always based on enzyme conformational changes. The principal objective of the present article is to examine whether recent experimental results on Ca2+-ATPase may in fact be better explained by assuming the existence of a direct chemiosmotic process. In the scheme proposed, free energy transduction between ATP and calcium is based on a transfer of solvation water between the acylphosphate bond and the bound calcium ions.
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Futai M, Kanazawa H. Structure and function of proton-translocating adenosine triphosphatase (F0F1): biochemical and molecular biological approaches. Microbiol Rev 1983; 47:285-312. [PMID: 6226867 PMCID: PMC281578 DOI: 10.1128/mr.47.3.285-312.1983] [Citation(s) in RCA: 200] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Scalla R, Amory A, Rigaud J, Goffeau A. Phosphorylated intermediate of a transport ATPase and activity of protein kinase in membranes from corn roots. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:525-30. [PMID: 6221927 DOI: 10.1111/j.1432-1033.1983.tb07393.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A maize-root microsomal fraction was enriched in ATPase by treatment with Triton X-100. This activity, which reached 1.2-2.0/mumol Pi x min-1 x mg protein-1, was specific for ATP, very slightly stimulated by K+, inhibited by orthovanadate and diethylstilbestrol, resistant to oligomycin and azide, and had a Km of 1.2 mM MgATP. Incubation of the microsomal fraction with [gamma 32-P]ATP followed by electrophoresis in acid conditions revealed the presence of several phosphoproteins. The phosphorylation of a 110000-Mr polypeptide reached the steady-state level in less than 5 s and rapidly turned over the phosphate group. The phosphorylation level was an hyperbolic function of the [ATP] with a Km of 0.6 mM, suggesting that the rate of Pi production was proportional to the phosphoprotein concentration. The extent of phosphoprotein was decreased by vanadate and diethylstilbestrol. The phosphorylation level was 30% decreased by 50 mM K+ or Na+ while the ATPase activity was slightly stimulated (12% and 5%, respectively). The polypeptide could not be phosphorylated in reverse by Pi. This phosphorylated intermediate from maize-root microsomes exhibits molecular properties characteristic of transport ATPases such as the yeast plasma membrane H+-translocating ATPase. This similarity indicates existence of a transport ATPase in plant plasma membranes. Three other plant microsomal polypeptides (Mr = 52000, 17000 and 16000) and a low molecular weight component (Mr less than 1000) were phosphorylated much more slowly, were not undergoing a rapid turnover and were not hydrolysed by hydroxylamine. These phosphoproteins and the Mr less than 1000 phosphorylated component were inhibited by vanadate and diethylstilbestrol. These properties are similar to those of the protein kinase activity recently described in yeast plasma membranes.
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