Metabolism controls dimerization of the chloroplast FoF1 ATP synthase in Chlamydomonas reinhardtii

Schwaßmann, Helena J.; Rexroth, Sascha; Seelert, Holger; Dencher, Norbert A.

doi:10.1016/j.febslet.2007.02.057

Cited by 22 publications

(12 citation statements)

References 31 publications

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“…However, so far, no direct effect of phosphorylation on ATP synthase activity has been demonstrated in vivo. Furthermore, a metabolically controlled dimerization of the C. reinhardtii plastid ATP synthase has been shown (Schwassmann et al, 2007), but an effect on enzyme activity has not been demonstrated yet. Therefore, the reason for the discrepancy between the downregulation of the ATP synthase contents and the less pronounced reduction in activity currently cannot be fully resolved.…”

Section: Excess Atp Synthase Capacity In Wild-type Plantsmentioning

confidence: 99%

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

et al. 2011

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Tobacco (Nicotiana tabacum) plants strictly adjust the contents of both ATP synthase and cytochrome b 6 f complex to the metabolic demand for ATP and NADPH. While the cytochrome b 6 f complex catalyzes the rate-limiting step of photosynthetic electron flux and thereby controls assimilation, the functional significance of the ATP synthase adjustment is unknown. Here, we reduced ATP synthase accumulation by an antisense approach directed against the essential nuclearencoded g-subunit (AtpC) and by the introduction of point mutations into the translation initiation codon of the plastidencoded atpB gene (encoding the essential b-subunit) via chloroplast transformation. Both strategies yielded transformants with ATP synthase contents ranging from 100 to <10% of wild-type levels. While the accumulation of the components of the linear electron transport chain was largely unaltered, linear electron flux was strongly inhibited due to decreased rates of plastoquinol reoxidation at the cytochrome b 6 f complex (photosynthetic control). Also, nonphotochemical quenching was triggered at very low light intensities, strongly reducing the quantum efficiency of CO 2 fixation. We show evidence that this is due to an increased steady state proton motive force, resulting in strong lumen overacidification, which in turn represses photosynthesis due to photosynthetic control and dissipation of excitation energy in the antenna bed. INTRODUCTIONThe capacity of the photosynthetic light reactions to provide ATP and NADPH must be closely adjusted to their metabolic consumption by the Calvin cycle, the subsequent reactions of dark metabolism such as starch synthesis, and other anabolic pathways within the chloroplast. Upon hyperactivity of the light reactions, the metabolic regeneration of NADP + , ADP, and P i will limit photosynthetic electron transport, resulting in detrimental side reactions. NADP + limitation would result in electron transfer to alternative acceptors, such as O 2 , generating reactive oxygen species. These can damage the photosynthetic apparatus itself and also initiate cell death responses (Kim et al., 2008).Reduced ADP and P i regeneration results in substrate limitation of the thylakoid ATP synthase, reducing proton efflux from the lumen and resulting in an increase of the proton motive force (pmf) across the thylakoid membrane (Takizawa et al., 2008;Kiirats et al., 2009). Under standard growth conditions, the pmf is partitioned into an electrochemical component (DC) and a proton gradient (DpH) in such a way that the pH value of the thylakoid lumen is usually kept between 7.0 and 6.5 (Takizawa et al., 2007). However, in response to short-term imbalances between proton translocation into the lumen by photosynthetic electron transport and use of the pmf for ATP synthesis, the pH of the thylakoid lumen can drop below 6.5. This initiates photoprotective feedback responses such as nonphotochemical quenching (qN), which is the thermal dissipation of excess excitation energy in the photosystem II (PSII) antenna bed in the...

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Section: Excess Atp Synthase Capacity In Wild-type Plantsmentioning

confidence: 99%

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

et al. 2011

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“…BN-PAGE with the Hoefer SE 600 system (18 3 16 3 0.15 cm 3 , 10 lanes) was performed as previously described (Schägger and von Jagow, 1991;Schwassmann et al, 2007); stacking gels with 3.5% acrylamide and separating gels with linear acrylamide gradients of 5 to 13% were used, and 250 mg solubilized protein was applied per lane.…”

Section: Bn-pagementioning

confidence: 99%

Functional Characterization of the Small Regulatory Subunit PetP from the Cytochrome b₆f Complex in Thermosynechococcus elongatus

Rexroth

Veit

et al. 2014

Plant Cell

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The cyanobacterial cytochrome b 6 f complex is central for the coordination of photosynthetic and respiratory electron transport and also for the balance between linear and cyclic electron transport. The development of a purification strategy for a highly active dimeric b 6 f complex from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 enabled characterization of the structural and functional role of the small subunit PetP in this complex. Moreover, the efficient transformability of this strain allowed the generation of a DpetP mutant. Analysis on the whole-cell level by growth curves, photosystem II light saturation curves, and P700 + reduction kinetics indicate a strong decrease in the linear electron transport in the mutant strain versus the wild type, while the cyclic electron transport via photosystem I and cytochrome b 6 f is largely unaffected. This reduction in linear electron transport is accompanied by a strongly decreased stability and activity of the isolated DpetP complex in comparison with the dimeric wild-type complex, which binds two PetP subunits. The distinct behavior of linear and cyclic electron transport may suggest the presence of two distinguishable pools of cytochrome b 6 f complexes with different functions that might be correlated with supercomplex formation.

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“…Furthermore, this kind of electrophoresis allows to enlighten the supramolecular organization of proteins (e.g. [2][3][4][5][6][7]) and even preparative applications are feasible [6,8]. Since the function of many enzymes depends on ATP, monitoring of ATP hydrolysis in native gels is an excellent tool to screen complex samples rapidly.…”

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confidence: 99%

“…1B, lane 3). Basing on preceding observations [2,3], the electrophoretic mobility is compared with a standard, i.e. the purified ATP synthase, to assign the bands.…”

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confidence: 99%

“…In such samples, besides the ATP synthase other protein complexes of photosynthesis are present. Thylakoid membranes from T. elongatus and photomixotrophically grown C. reinhardtii were isolated as previously described [3,32,33]. Upon solubilization of thylakoid membranes according to [2] with digitonin (Molekula, Gillingham, UK) or n-dodecyl-b-Dmaltoside (DDM) (Calbiochem, Darmstadt, Germany), these samples were directly loaded onto blue-native gradient gels.…”

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Highly sensitive detection of ATPase activity in native gels

et al. 2009

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Native electrophoresis is a powerful tool for the separation of intact protein complexes. By incubating such gels in a suitable reaction solution, specific enzyme activities can be screened comprehensively. The recent standard procedure for determination of ATP hydrolysis activity in blue or clear native gels is based on formation of a lead phosphate precipitate. The resulting white bands are challenging for detection and documentation of low activities. For the analysis of photosynthetic ATP synthases, the method has to be adapted to deregulate the inhibition of latent ATPase functions. Therefore, we introduced an incubation of gels in detergent solution, whereby taurodeoxycholate turned out to be the most efficient activator. In order to detect low ATPase activities, a short additional incubation step subsequent to the formation of lead phosphate is recommended. By adding ammonium sulfide, the white bands are converted into brownish-black bands of lead sulfide. Our new procedure sustains the linear quantitation range of the original lead phosphate protocol and moreover expands the detection limit.

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Metabolism controls dimerization of the chloroplast F_oF₁ ATP synthase in Chlamydomonas reinhardtii

Cited by 22 publications

References 31 publications

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

Functional Characterization of the Small Regulatory Subunit PetP from the Cytochrome b₆f Complex in Thermosynechococcus elongatus

Highly sensitive detection of ATPase activity in native gels

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Metabolism controls dimerization of the chloroplast FoF1 ATP synthase in Chlamydomonas reinhardtii

Cited by 22 publications

References 31 publications

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO2 Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO2 Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

Functional Characterization of the Small Regulatory Subunit PetP from the Cytochrome b6f Complex in Thermosynechococcus elongatus

Highly sensitive detection of ATPase activity in native gels

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Metabolism controls dimerization of the chloroplast F_oF₁ ATP synthase in Chlamydomonas reinhardtii

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

ATP Synthase Repression in Tobacco Restricts Photosynthetic Electron Transport, CO₂ Assimilation, and Plant Growth by Overacidification of the Thylakoid Lumen

Functional Characterization of the Small Regulatory Subunit PetP from the Cytochrome b₆f Complex in Thermosynechococcus elongatus