scholarly journals Energy conservation by a hydrogenase-dependent chemiosmotic mechanism in an ancient metabolic pathway

2019 ◽  
Vol 116 (13) ◽  
pp. 6329-6334 ◽  
Author(s):  
Marie Charlotte Schoelmerich ◽  
Volker Müller
Keyword(s):  
Energy Conservation ◽  
Atp Synthase ◽  
Membrane Vesicles ◽  
Resting Cells ◽  
Respiratory Enzyme ◽  
Acetyl Coa Pathway ◽  
Acetogenic Bacterium ◽  
Genome Analyses ◽  
Chemiosmotic Coupling ◽  
Energy Converting

The ancient reductive acetyl-CoA pathway is employed by acetogenic bacteria to form acetate from inorganic energy sources. Since the central pathway does not gain net ATP by substrate-level phosphorylation, chemolithoautotrophic growth relies on the additional formation of ATP via a chemiosmotic mechanism. Genome analyses indicated that some acetogens only have an energy-converting, ion-translocating hydrogenase (Ech) as a potential respiratory enzyme. Although the Ech-encoding genes are widely distributed in nature, the proposed function of Ech as an ion-translocating chemiosmotic coupling site has neither been demonstrated in bacteria nor has it been demonstrated that it can be the only energetic coupling sites in microorganisms that depend on a chemiosmotic mechanism for energy conservation. Here, we show that the Ech complex of the thermophilic acetogenic bacteriumThermoanaerobacter kivuiis indeed a respiratory enzyme. Experiments with resting cells prepared fromT. kivuicultures grown on carbon monoxide (CO) revealed CO oxidation coupled to H2formation and the generation of a transmembrane electrochemical ion gradient (Δµ∼ion). Inverted membrane vesicles (IMVs) prepared from CO-grown cells also produced H2and ATP from CO (via a loosely attached CO dehydrogenase) or a chemical reductant. Finally, we show that Ech activity led to the translocation of both H+and Na+across the membrane of the IMVs. The H+gradient was then used by the ATP synthase for energy conservation. These data demonstrate that the energy-converting hydrogenase in concert with an ATP synthase may be the simplest form of respiration; it combines carbon dioxide fixation with the synthesis of ATP in an ancient pathway.

scholarly journals Phospholipase D2 Localizes to the Plasma Membrane and Regulates Angiotensin II Receptor Endocytosis

2004 ◽  
Vol 15 (3) ◽  
pp. 1024-1030 ◽  
Author(s):  
Guangwei Du ◽  
Ping Huang ◽  
Bruce T. Liang ◽  
Michael A. Frohman
Keyword(s):  
Plasma Membrane ◽  
Angiotensin Ii ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Cell Types ◽  
Dominant Negative ◽  
Secretory Cells ◽  
Resting Cells ◽  
Angiotensin Ii Receptor ◽  
Multiple Cell

Phospholipase D (PLD) is a key facilitator of multiple types of membrane vesicle trafficking events. Two PLD isoforms, PLD1 and PLD2, exist in mammals. Initial studies based on overexpression studies suggested that in resting cells, human PLD1 localized primarily to the Golgi and perinuclear vesicles in multiple cell types. In contrast, overexpressed mouse PLD2 was observed to localize primarily to the plasma membrane, although internalization on membrane vesicles was observed subsequent to serum stimulation. A recent report has suggested that the assignment of PLD2 to the plasma membrane is in error, because the endogenous isoform in rat secretory cells was imaged and found to be present primarily in the Golgi apparatus. We have reexamined this issue by using a monoclonal antibody specific for mouse PLD2, and find, as reported initially using overexpression studies, that endogenous mouse PLD2 is detected most readily at the plasma membrane in multiple cell types. In addition, we report that mouse, rat, and human PLD2 when overexpressed all similarly localize to the plasma membrane in cell lines from all three species. Finally, studies conducted using overexpression of wild-type active or dominant-negative isoforms of PLD2 and RNA interference-mediated targeting of PLD2 suggest that PLD2 functions at the plasma membrane to facilitate endocytosis of the angiotensin II type 1 receptor.

Turnover Number of Escherichia coli F0F1 ATP Synthase for ATP Synthesis in Membrane Vesicles

1997 ◽  
Vol 243 (1-2) ◽  
pp. 336-343 ◽  
Author(s):  
Carsten Etzold ◽  
Gabriele Deckers-Hebestreit ◽  
Karlheinz Altendorf
Keyword(s):  
Escherichia Coli ◽  
Atp Synthase ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Turnover Number ◽  
F0f1 Atp Synthase

scholarly journals Targeting Mycobacterial F-ATP Synthase C-Terminal α Subunit Interaction Motif on Rotary Subunit γ

Antibiotics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Amaravadhi Harikishore ◽  
Chui-Fann Wong ◽  
Priya Ragunathan ◽  
Dennis Litty ◽  
Volker Müller ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Membrane Vesicles ◽  
Α Subunit ◽  
Rotational States ◽  
C Terminus ◽  
Inverted Membrane Vesicles ◽  
Hydrolysis Of ◽  
Micromolar Range

Mycobacteria regulate their energy (ATP) levels to sustain their survival even in stringent living conditions. Recent studies have shown that mycobacteria not only slow down their respiratory rate but also block ATP hydrolysis of the F-ATP synthase (α3:β3:γ:δ:ε:a:b:b’:c9) to maintain ATP homeostasis in situations not amenable for growth. The mycobacteria-specific α C-terminus (α533-545) has unraveled to be the major regulative of latent ATP hydrolysis. Its deletion stimulates ATPase activity while reducing ATP synthesis. In one of the six rotational states of F-ATP synthase, α533-545 has been visualized to dock deep into subunit γ, thereby blocking rotation of γ within the engine. The functional role(s) of this C-terminus in the other rotational states are not clarified yet and are being still pursued in structural studies. Based on the interaction pattern of the docked α533-545 region with subunit γ, we attempted to study the druggability of the α533-545 motif. In this direction, our computational work has led to the development of an eight-featured α533-545 peptide pharmacophore, followed by database screening, molecular docking, and pose selection, resulting in eleven hit molecules. ATP synthesis inhibition assays using recombinant ATP synthase as well as mycobacterial inverted membrane vesicles show that one of the hits, AlMF1, inhibited the mycobacterial F-ATP synthase in a micromolar range. The successful targeting of the α533-545-γ interaction motif demonstrates the potential to develop inhibitors targeting the α site to interrupt rotary coupling with ATP synthesis.

scholarly journals Halotolerant Cyanobacterium Aphanothece halophytica Contains an Na+-dependent F1F0-ATP Synthase with a Potential Role in Salt-stress Tolerance

2011 ◽  
Vol 286 (12) ◽  
pp. 10169-10176 ◽  
Author(s):  
Kanteera Soontharapirakkul ◽  
Worrawat Promden ◽  
Nana Yamada ◽  
Hakuto Kageyama ◽  
Aran Incharoensakdi ◽  
...  
Keyword(s):  
Salt Stress ◽  
Stress Tolerance ◽  
Atp Synthase ◽  
Potential Role ◽  
Cytoplasmic Membrane ◽  
Membrane Vesicles ◽  
Aphanothece Halophytica ◽  
Salt Stress Tolerance ◽  
Tributyltin Chloride ◽  
Inverted Membrane Vesicles

Aphanothece halophytica is a halotolerant alkaliphilic cyanobacterium that can grow in media of up to 3.0 m NaCl and pH 11. Here, we show that in addition to a typical H+-ATP synthase, Aphanothece halophytica contains a putative F1F0-type Na+-ATP synthase (ApNa+-ATPase) operon (ApNa+-atp). The operon consists of nine genes organized in the order of putative subunits β, ϵ, I, hypothetical protein, a, c, b, α, and γ. Homologous operons could also be found in some cyanobacteria such as Synechococcus sp. PCC 7002 and Acaryochloris marina MBIC11017. The ApNa+-atp operon was isolated from the A. halophytica genome and transferred into an Escherichia coli mutant DK8 (Δatp) deficient in ATP synthase. The inverted membrane vesicles of E. coli DK8 expressing ApNa+-ATPase exhibited Na+-dependent ATP hydrolysis activity, which was inhibited by monensin and tributyltin chloride, but not by the protonophore, carbonyl cyanide m-chlorophenyl hydrazone (CCCP). The Na+ ion protected the inhibition of ApNa+-ATPase by N,N′-dicyclohexylcarbodiimide. The ATP synthesis activity was also observed using the Na+-loaded inverted membrane vesicles. Expression of the ApNa+-atp operon in the heterologous cyanobacterium Synechococcus sp. PCC 7942 showed its localization in the cytoplasmic membrane fractions and increased tolerance to salt stress. These results indicate that A. halophytica has additional Na+-dependent F1F0-ATPase in the cytoplasmic membrane playing a potential role in salt-stress tolerance.

scholarly journals Helical arrays of U-shaped ATP synthase dimers form tubular cristae in ciliate mitochondria

2016 ◽  
Vol 113 (30) ◽  
pp. 8442-8447 ◽  
Author(s):  
Alexander W. Mühleip ◽  
Friederike Joos ◽  
Christoph Wigge ◽  
Achilleas S. Frangakis ◽  
Werner Kühlbrandt ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Protein Complexes ◽  
Paramecium Tetraurelia ◽  
Mitochondrial Atp Synthase ◽  
Structural Differences ◽  
Membrane Protein Complexes ◽  
Subtomogram Averaging ◽  
Electron Cryotomography ◽  
Energy Converting

F1Fo-ATP synthases are universal energy-converting membrane protein complexes that synthesize ATP from ADP and inorganic phosphate. In mitochondria of yeast and mammals, the ATP synthase forms V-shaped dimers, which assemble into rows along the highly curved ridges of lamellar cristae. Using electron cryotomography and subtomogram averaging, we have determined the in situ structure and organization of the mitochondrial ATP synthase dimer of the ciliate Paramecium tetraurelia. The ATP synthase forms U-shaped dimers with parallel monomers. Each complex has a prominent intracrista domain, which links the c-ring of one monomer to the peripheral stalk of the other. Close interaction of intracrista domains in adjacent dimers results in the formation of helical ATP synthase dimer arrays, which differ from the loose dimer rows in all other organisms observed so far. The parameters of the helical arrays match those of the cristae tubes, suggesting the unique features of the P. tetraurelia ATP synthase are directly responsible for generating the helical tubular cristae. We conclude that despite major structural differences between ATP synthase dimers of ciliates and other eukaryotes, the formation of ATP synthase dimer rows is a universal feature of mitochondria and a fundamental determinant of cristae morphology.

Membrane vesicles fromSynechocystis 6803 showing proton and electron transport and high ATP synthase activities

1996 ◽  
Vol 47 (3) ◽  
pp. 301-305 ◽  
Author(s):  
Marijke J. C. Scholts ◽  
Pepijn Aardewijn ◽  
Hendrika S. Van Walraven
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Membrane Vesicles

scholarly journals 2,3-Butanediol Metabolism in the Acetogen Acetobacterium woodii

2015 ◽  
Vol 81 (14) ◽  
pp. 4711-4719 ◽  
Author(s):  
Verena Hess ◽  
Olga Oyrik ◽  
Dragan Trifunović ◽  
Volker Müller
Keyword(s):  
Coenzyme A ◽  
Cell Suspensions ◽  
Resting Cells ◽  
Dependent Manner ◽  
Acetobacterium Woodii ◽  
Metabolite Analysis ◽  
Acetyl Coenzyme A ◽  
Content Type ◽  
Acetyl Coenzyme ◽  
Acetogenic Bacterium

ABSTRACTThe acetogenic bacteriumAcetobacterium woodiiis able to reduce CO2to acetate via the Wood-Ljungdahl pathway. Only recently we demonstrated that degradation of 1,2-propanediol byA. woodiiwas not dependent on acetogenesis, but that it is disproportionated to propanol and propionate. Here, we analyzed the metabolism ofA. woodiion another diol, 2,3-butanediol. Experiments with growing and resting cells, metabolite analysis and enzymatic measurements revealed that 2,3-butanediol is oxidized in an NAD+-dependent manner to acetate via the intermediates acetoin, acetaldehyde, and acetyl coenzyme A. Ethanol was not detected as an end product, either in growing cultures or in cell suspensions. Apparently, all reducing equivalents originating from the oxidation of 2,3-butanediol were funneled into the Wood-Ljungdahl pathway to reduce CO2to another acetate. Thus, the metabolism of 2,3-butanediol requires the Wood-Ljungdahl pathway.

scholarly journals Direct interaction between Rab3D and the polymeric immunoglobulin receptor and trafficking through regulated secretory vesicles in lacrimal gland acinar cells

2008 ◽  
Vol 294 (3) ◽  
pp. C662-C674 ◽  
Author(s):  
Eunbyul Evans ◽  
Wenzheng Zhang ◽  
Galina Jerdeva ◽  
Chiao-Yu Chen ◽  
Xuequn Chen ◽  
...  
Keyword(s):  
Lacrimal Gland ◽  
Secretory Pathway ◽  
Primary Cultures ◽  
Direct Interaction ◽  
Membrane Vesicles ◽  
Acinar Cells ◽  
Small Gtpase ◽  
Secretory Proteins ◽  
Major Protein ◽  
Resting Cells

The lacrimal gland is responsible for tear production, and a major protein found in tears is secretory component (SC), the proteolytically cleaved fragment of the extracellular domain of the polymeric Ig receptor (pIgR), which is the receptor mediating the basal-to-apical transcytosis of polymeric immunoglobulins across epithelial cells. Immunofluorescent labeling of rabbit lacrimal gland acinar cells (LGACs) revealed that the small GTPase Rab3D, a regulated secretory vesicle marker, and the pIgR are colocalized in subapical membrane vesicles. In addition, the secretion of SC from primary cultures of LGACs was stimulated by the cholinergic agonist carbachol (CCH), and its release rate was very similar to that of other regulated secretory proteins in LGACs. In pull-down assays from resting LGACs, recombinant wild-type Rab3D (Rab3DWT) or the GDP-locked mutant Rab3DT36N both pulled down pIgR, but the GTP-locked mutant Rab3DQ81L did not. When the pull-down assays were performed in the presence of guanosine-5′-(γ-thio)-triphosphate, GTP, or guanosine-5′- O-(2-thiodiphosphate), binding of Rab3DWT to pIgR was inhibited. In blot overlays, recombinant Rab3DWT bound to immunoprecipitated pIgR, suggesting that Rab3D and pIgR may interact directly. Adenovirus-mediated overexpression of mutant Rab3DT36N in LGACs inhibited CCH-stimulated SC release, and, in CCH-stimulated LGACs, pull down of pIgR with Rab3DWT and colocalization of pIgR with endogenous Rab3D were decreased relative to resting cells, suggesting that the pIgR-Rab3D interaction may be modulated by secretagogues. These data suggest that the novel localization of pIgR to the regulated secretory pathway of LGACs and its secretion therefrom may be affected by its novel interaction with Rab3D.

scholarly journals Regulation of Caffeate Respiration in the Acetogenic Bacterium Acetobacterium woodii

2007 ◽  
Vol 73 (11) ◽  
pp. 3630-3636 ◽  
Author(s):  
Sabrina Dilling ◽  
Frank Imkamp ◽  
Silke Schmidt ◽  
Volker Müller
Keyword(s):  
De Novo ◽  
Electron Acceptors ◽  
Lag Phase ◽  
Resting Cells ◽  
Acetobacterium Woodii ◽  
Methyl Group ◽  
Differential Flow ◽  
Energy Conserving ◽  
A Cell ◽  
Acetogenic Bacterium

ABSTRACT The anaerobic acetogenic bacterium Acetobacterium woodii can conserve energy by oxidation of various substrates coupled to either carbonate or caffeate respiration. We used a cell suspension system to study the regulation and kinetics of induction of caffeate respiration. After addition of caffeate to suspensions of fructose-grown cells, there was a lag phase of about 90 min before caffeate reduction commenced. However, in the presence of tetracycline caffeate was not reduced, indicating that de novo protein synthesis is required for the ability to respire caffeate. Induction also took place in the presence of CO2, and once a culture was induced, caffeate and CO2 were used simultaneously as electron acceptors. Induction of caffeate reduction was also observed with H2 plus CO2 as the substrate, but the lag phase was much longer. Again, caffeate and CO2 were used simultaneously as electron acceptors. In contrast, during oxidation of methyl groups derived from methanol or betaine, acetogenesis was the preferred energy-conserving pathway, and caffeate reduction started only after acetogenesis was completed. The differential flow of reductants was also observed with suspensions of resting cells in which caffeate reduction was induced prior to harvest of the cells. These cell suspensions utilized caffeate and CO2 simultaneously with fructose or hydrogen as electron donors, but CO2 was preferred over caffeate during methyl group oxidation. Caffeate-induced resting cells could reduce caffeate and also p-coumarate or ferulate with hydrogen as the electron donor. p-Coumarate or ferulate also served as an inducer for caffeate reduction. Interestingly, caffeate-induced cells reduced ferulate in the absence of an external reductant, indicating that caffeate also induces the enzymes required for oxidation of the methyl group of ferulate.

scholarly journals On the extent of localization of the energized membrane state in chromatophores from Rhodopseudomonas capsulata N22

1982 ◽  
Vol 206 (2) ◽  
pp. 351-357 ◽  
Author(s):  
G D Hitchens ◽  
D B Kell
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Relative Number ◽  
Coupling Model ◽  
Rhodopseudomonas Capsulata ◽  
Apparent Paradox ◽  
Model Free ◽  
Transport Chain ◽  
Chemiosmotic Coupling

1. The principle of the double-inhibitor titration method for assessing competing models of electron transport phosphorylation is expounded. 2. This principle is applied to photophosphorylation by chromatophores from Rhodopseudomonas capsulata N22. 3. It is found that, in contrast to the predictions of the chemiosmotic coupling model, free energy transfer is confined to individual electron transport chain and ATP synthase complexes. 4. This conclusion is not weakened by arguments concerning, the degree of uncoupling in the native chromatophore preparation or the relative number of electron transport chain and ATP synthase complexes present. 5. Photophosphorylation is completely inhibited by the uncoupler SF 6847 at a concentration corresponding to 0.31 molecules per electron transport chain. 6. The apparent paradox is solved by the proposal, consistent with the available evidence on the mode of action of uncouplers, that uncoupler binding causes a co-operative conformation transition in the chromatophore membrane, which leads to uncoupling and which is not present in the absence of uncoupler.

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