scholarly journals Feedback limitation of photosynthesis at high CO2 acts by modulating the activity of the chloroplast ATP synthase

2009 ◽  
Vol 36 (11) ◽  
pp. 893 ◽  
Author(s):  
Olavi Kiirats ◽  
Jeffrey A. Cruz ◽  
Gerald E. Edwards ◽  
David M. Kramer
Keyword(s):  
Electron Transfer ◽  
Atp Synthase ◽  
Atp Synthesis ◽  
Nicotiana Sylvestris ◽  
O2 Evolution ◽  
High Co2 ◽  
Chloroplast Atp Synthase ◽  
Low Co2 ◽  
Photosynthetic Electron Transfer

It was previously shown that photosynthetic electron transfer is controlled under low CO2 via regulation of the chloroplast ATP synthase. In the current work, we studied the regulation of photosynthesis under feedback limiting conditions, where photosynthesis is limited by the capacity to utilise triose-phosphate for synthesis of end products (starch or sucrose), in a starch-deficient mutant of Nicotiana sylvestris Speg. & Comes. At high CO2, we observed feedback control that was progressively reversed by increasing O2 levels from 2 to 40%. The activity of the ATP synthase, probed in vivo by the dark-interval relaxation kinetics of the electrochromic shift, was proportional to the O2-induced increases in O2 evolution from PSII (JO2), as well as the sum of Rubisco oxygenation (vo) and carboxylation (vc) rates. The altered ATP synthase activity led to changes in the light-driven proton motive force, resulting in regulation of the rate of plastoquinol oxidation at the cytochrome b6f complex, quantitatively accounting for the observed control of photosynthetic electron transfer. The ATP content of the cell decreases under feedback limitation, suggesting that the ATP synthesis was downregulated to a larger extent than ATP consumption. This likely resulted in slowing of ribulose bisphosphate regeneration and JO2). Overall, our results indicate that, just as at low CO2, feedback limitations control the light reactions of photosynthesis via regulation of the ATP synthase, and can be reconciled with regulation via stromal Pi, or an unknown allosteric affector.

scholarly journals ECS-based investigation of chloroplast ATP synthase regulation

2020 ◽  
Author(s):  
Felix Buchert ◽  
Benjamin Bailleul ◽  
Pierre Joliot
Keyword(s):  
Atp Synthase ◽  
Redox Regulation ◽  
Spectroscopic Method ◽  
Atp Synthesis ◽  
Redox States ◽  
Chloroplast Atp Synthase ◽  
Γ Subunit ◽  
Synthase Regulation

AbstractThe chloroplast ATP synthase (CF1Fo) contains a specific feature to the green lineage: a γ-subunit redox domain which contains a cysteine couple and interacts with the torque-generating βDELSEED-loop. Based on the recently solved structure of this domain, it was proposed to function as a chock. In vitro, γ-disulfide formation slows down the activity of the CF1Fo at low transmembrane electrochemical proton gradient . Here, we utilize in vivo absorption spectroscopy measurements for functional CF1Fo activity characterization in Arabidopsis leaves. The spectroscopic method allows us to measure the present in dark-adapted leaves, and to identify its mitochondrial sources. Furthermore, we follow the fate of the extra generated by an illumination, including its osmotic and electric components, and from there we estimate the lifetime of the light-generated ATP. In contrast with a previous report [Joliot and Joliot, Biochim. Biophys. Acta, 1777 (2008) 676-683], the CF1Fo γ-subunit exists mostly in an oxidized form in the dark-adapted state. To study the redox regulation of the CF1Fo, we used thiol agent infiltration in WT and a mutant that does not form the γ-disulfide. The obtained -dependent CF1Fo activity profile in the two γ-redox states in vivo reconciles with previous biochemical in vitro findings [Junesch and Gräber, Biochim. Biophys. Acta, 893 (1987) 275-288]. The highest rates of ATP synthesis we measured in the two γ-redox state were similar at high . In the presence of the γ-dithiol, similar rates were obtained at a ~45 mV lower value compared to the oxidized state, which closely resembled the energetic gap of 0.7 ΔpH units reported in vitro.

scholarly journals Aerobic Growth of Escherichia coli Is Reduced, and ATP Synthesis Is Selectively Inhibited when Five C-terminal Residues Are Deleted from the ϵ Subunit of ATP Synthase

2015 ◽  
Vol 290 (34) ◽  
pp. 21032-21041 ◽  
Author(s):  
Naman B. Shah ◽  
Thomas M. Duncan
Keyword(s):  
Escherichia Coli ◽  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Intrinsic Rate ◽  
Synthesis Rate ◽  
Final Segment ◽  
Rotary Catalysis

F-type ATP synthases are rotary nanomotor enzymes involved in cellular energy metabolism in eukaryotes and eubacteria. The ATP synthase from Gram-positive and -negative model bacteria can be autoinhibited by the C-terminal domain of its ϵ subunit (ϵCTD), but the importance of ϵ inhibition in vivo is unclear. Functional rotation is thought to be blocked by insertion of the latter half of the ϵCTD into the central cavity of the catalytic complex (F1). In the inhibited state of the Escherichia coli enzyme, the final segment of ϵCTD is deeply buried but has few specific interactions with other subunits. This region of the ϵCTD is variable or absent in other bacteria that exhibit strong ϵ-inhibition in vitro. Here, genetically deleting the last five residues of the ϵCTD (ϵΔ5) caused a greater defect in respiratory growth than did the complete absence of the ϵCTD. Isolated membranes with ϵΔ5 generated proton-motive force by respiration as effectively as with wild-type ϵ but showed a nearly 3-fold decrease in ATP synthesis rate. In contrast, the ϵΔ5 truncation did not change the intrinsic rate of ATP hydrolysis with membranes. Further, the ϵΔ5 subunit retained high affinity for isolated F1 but reduced the maximal inhibition of F1-ATPase by ϵ from >90% to ∼20%. The results suggest that the ϵCTD has distinct regulatory interactions with F1 when rotary catalysis operates in opposite directions for the hydrolysis or synthesis of ATP.

Abstract MP247: Mitochondrial Complex V Is Regulated By GRK2 In The Heart

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Kimberly Ferrero ◽  
Jessica M Pfleger ◽  
Kurt Chuprun ◽  
Eric Barr ◽  
Erhe Gao ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Cardiac Injury ◽  
Atp Synthesis ◽  
Cardiac Metabolism ◽  
Neonatal Rat ◽  
Interacting Proteins ◽  
Atp Production

The GPCR kinase GRK2 is highly expressed the heart; importantly, during cardiac injury or heart failure (HF) both levels and activity of GRK2 increase. The role of GRK2 during HF is canonically studied upstream of β-adrenergic desensitization. However, GRK2 has a large interactome and noncanonical functions for this kinase are being uncovered. We have discovered that in the heart, GRK2 translocates to mitochondria ( mtGRK2 ) following injury and is associated with negative effects on cardiac metabolism. Thus, we have sought to identify the mechanism(s) by which GRK2 can regulate mitochondrial function. We hypothesize that mtGRK2 interacts with proteins which regulate bioenergetics and substrate utilization, and this never-before-described role may partially explain the altered mitochondrial phenotype seen following cardiac injury or HF. Stress-induced mitochondrial translocation of GRK2 was validated in neonatal rat ventricular myocytes, murine heart tissue and a cardiac-derived cell line. Consequently, the GRK2 interactome was mapped basally and under stress conditions in vitro, in vivo , and with tagged recombinant peptides. GRK2-interacting proteins were isolated via immunoprecipitation and analyzed via liquid chromatography-mass spectroscopy (LCMS). Proteomics analysis (IPA; Qiagen) identified mtGRK2 interacting proteins which were also involved in mitochondrial dysfunction. Excitingly, Complexes I, II, IV and V (ATP synthase) of the electron transport chain (ETC) were identified in the subset of mtGRK2-dysfunction partners. Several mtGRK2-ETC interactions were increased following stress, particularly those in Complex V. We further established that mtGRK2 phosphorylates some of the subunits of Complex V, particularly the ATP synthase barrel which is critical for ATP production in the heart. Specific amino acid residues on these subunits have been identified using PTM-LCMS and are currently being validated in a murine model of myocardial infarction. To support these data, we have also determined that alterations in either the levels or kinase activity of GRK2 appear to alter the enzymatic activity of Complex V in vitro , thus altering ATP production. In summary, the phosphorylation of the ATP synthesis machinery by mtGRK2 may be regulating some of the phenotypic effects of injured or failing hearts such as increased ROS production and reduced fatty acid metabolism. Research is ongoing in our lab to elucidate the novel role of GRK2 in regulating mitochondrial bioenergetics and cell death, thus uncovering an exciting, druggable novel target for rescuing cardiac function in patients with injured and/or failing hearts.

Hypothesis: versatile function of ferredoxin-NADP+ reductase in cyanobacteria provides regulation for transient photosystem I-driven cyclic electron flow

2002 ◽  
Vol 29 (3) ◽  
pp. 201 ◽  
Author(s):  
Hans C. P. Matthijs ◽  
Robert Jeanjean ◽  
Nataliya Yeremenko ◽  
Jef Huisman ◽  
Francoise Joset ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Salt Stress ◽  
De Novo ◽  
Electron Flow ◽  
High Co2 ◽  
Partial Restoration ◽  
Synechocystis Pcc6803 ◽  
Low Co2 ◽  
Cyclic Electron Transfer

Pseudo-reversion of the high-CO2 requiring phenotype of the NADH dehydrogenase type 1-impaired mutant of Synechocystis PCC6803, strain M55, by salt stress coincides with partial restoration of PSI-driven cyclic electron transfer. In M55, the complete family of D proteins (D1–D6) that are needed for electron transfer through the complex is lacking. Adaptation to salt stress requires de novo synthesis of full-length 47-kDa ferredoxin-NADP+ reductase (FNR). A mutant created in the M55 background, which only expresses truncated chloroplast 37-kDa FNR cannot adapt to salt stress and refrains from growth in low CO2. A special feature of FNR in cyanobacteria is the relatively high molecular mass of 44–48 kDa. A positively charged extended N-terminal domain of the cyanobacterial enzyme defines the extra mass. The extension likely plays a key role in the salt-stress inducible enhancement of PSI-driven cyclic electron transfer, and in the pseudo-reversion of the high-CO2 requiring phenotype of M55. Data acquired with several other cyanobacteria and the oxychlorobacterium Prochlorothrix hollandica contributed to the present hypothesis. It proposes that FNR is involved in regulation of inducible and transient PSI cyclic electron transfer in cyanobacteria via a thylakoid surface charge and conditional-proteolysis steered mechanism.

Kinetics of Proton-Transport-Coupled ATP Synthesis Catalyzed by the Chloroplast ATP Synthase

1986 ◽  
Vol 90 (11) ◽  
pp. 1034-1040 ◽  
Author(s):  
P. Gräber ◽  
P. Fromme ◽  
U. Junesch ◽  
G. Schmidt ◽  
G. Thulke
Keyword(s):  
Atp Synthase ◽  
Proton Transport ◽  
Atp Synthesis ◽  
Chloroplast Atp Synthase ◽  
Kinetics Of

scholarly journals A critical appraisal of evidence for localized energy coupling. Kinetic studies on liposomes containing bacteriorhodopsin and ATP synthase

1985 ◽  
Vol 230 (2) ◽  
pp. 543-549 ◽  
Author(s):  
R L Van der Bend ◽  
J Petersen ◽  
J A Berden ◽  
K Van Dam ◽  
H V Westerhoff
Keyword(s):  
Electron Transfer ◽  
Atp Synthase ◽  
Critical Appraisal ◽  
Atp Synthesis ◽  
Kinetic Studies ◽  
Energy Coupling ◽  
Proton Pumps ◽  
Specific Interactions ◽  
Mitochondrial Atp Synthase ◽  
Different Levels

In intact systems (chloroplasts, mitochondria and bacteria) many experiments have been reported which are indicative of localized coupling between ATP synthase and electron transfer complexes. We have carried out similar experiments with a system in which we may assume that specific interactions between the proton pumps are absent: reconstituted vesicles containing bacteriorhodopsin and yeast mitochondrial ATP synthase. The only experiment that gives results which differ from those previously published for intact systems concerns the effect of uncouplers on the rate of ATP synthesis at different levels of inhibition of the ATP synthase. We propose that this type of experiment may discriminate between localized and delocalized coupling.

The C-Terminal Domain of the ε Subunit of the Chloroplast ATP Synthase Is Not Required for ATP Synthesis†

Biochemistry ◽  
2002 ◽  
Vol 41 (51) ◽  
pp. 15130-15134 ◽  
Author(s):  
Kristine F. Nowak ◽  
Vazha Tabidze ◽  
Richard E. McCarty
Keyword(s):  
Atp Synthase ◽  
Atp Synthesis ◽  
Chloroplast Atp Synthase ◽  
Terminal Domain

Submergence of Rice. I. Growth and Photosynthetic Response to CO2 Enrichment of Floodwater

1989 ◽  
Vol 16 (3) ◽  
pp. 251 ◽  
Author(s):  
TL Setter ◽  
I Waters ◽  
I Wallace ◽  
P Bhekasut ◽  
H Greenway
Keyword(s):  
Co2 Enrichment ◽  
Co2 Concentration ◽  
O2 Evolution ◽  
Photosynthetic Response ◽  
Submerged Plants ◽  
High Co2 ◽  
Low Co2 ◽  
O2 Concentration ◽  
Photosynthetic O2 Evolution ◽  
Rice Leaves

Growth and photosynthetic response of lowland rice following complete submergence is related to the concentration of CO2 dissolved in floodwater. Submergence of plants in stagnant solution at low CO2 concentration or solution gassed with air at 0.03 kPa CO2 (equilibrium of 0.01 mol m-3 dissolved CO2) decreased carbohydrates, and little or no growth occurred. Plants submerged in solutions gassed with 3-20 kPa CO2 in air (equilibrium of 0.9-6 mol m-3 CO2) showed at most small decreases in carbohydrates, and growth was up to 100% of the non-submerged plants. At pH 7.5, there was little net photosynthetic O2 evolution by detached submerged leaves even at high HCO3- concentrations, which suggests that these rice leaves could utilise only CO2 and not HCO3-. At pH 6.5, O2 evolution in solutions in equilibrium with 7.4 kPa CO2 was 3-4 fold higher than in solutions in equilibrium with 0.6 kPa CO2. Photorespiration was indicated by a decrease in the rate of net O2 evolution with increasing external O2. In stagnant solutions this reduction of O2 evolution was pronounced; at a CO2 concentration of 0.25 mol m-3 net O2 evolution ceased when the O2 concentration in the water had reached only 0.125 mol m-3. The requirement of photosynthesis for a combination of high CO2 concentrations and low external O2 was presumably due to slow diffusion of these gases in the unstirred layer of solution around the leaves.

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