scholarly journals Light-inducedpsbAtranslation in plants is triggered by photosystem II damage via an assembly-linked autoregulatory circuit

2020 ◽  
Vol 117 (35) ◽  
pp. 21775-21784 ◽  
Author(s):  
Prakitchai Chotewutmontri ◽  
Alice Barkan
Keyword(s):  
Photosystem Ii ◽  
Action Spectrum ◽  
Photosynthetic Electron Transport ◽  
Early Step ◽  
Translation Elongation ◽  
Membrane Complex ◽  
Global Increase ◽  
Autoregulatory Mechanism ◽  
Repair Cycle ◽  
Stimulation Of

The D1 reaction center protein of photosystem II (PSII) is subject to light-induced damage. Degradation of damaged D1 and its replacement by nascent D1 are at the heart of a PSII repair cycle, without which photosynthesis is inhibited. In mature plant chloroplasts, light stimulates the recruitment of ribosomes specifically topsbAmRNA to provide nascent D1 for PSII repair and also triggers a global increase in translation elongation rate. The light-induced signals that initiate these responses are unclear. We present action spectrum and genetic data indicating that the light-induced recruitment of ribosomes topsbAmRNA is triggered by D1 photodamage, whereas the global stimulation of translation elongation is triggered by photosynthetic electron transport. Furthermore, mutants lacking HCF136, which mediates an early step in D1 assembly, exhibit constitutively highpsbAribosome occupancy in the dark and differ in this way from mutants lacking PSII for other reasons. These results, together with the recent elucidation of a thylakoid membrane complex that functions in PSII assembly, PSII repair, andpsbAtranslation, suggest an autoregulatory mechanism in which the light-induced degradation of D1 relieves repressive interactions between D1 and translational activators in the complex. We suggest that the presence of D1 in this complex coordinates D1 synthesis with the need for nascent D1 during both PSII biogenesis and PSII repair in plant chloroplasts.

scholarly journals Light-induced psbA translation in plants is triggered by photosystem II damage via an assembly-linked autoregulatory circuit

2020 ◽  
Author(s):  
Prakitchai Chotewutmontri ◽  
Alice Barkan
Keyword(s):  
Photosystem Ii ◽  
Reaction Center ◽  
Action Spectrum ◽  
Photosynthetic Electron Transport ◽  
Oxygenic Photosynthesis ◽  
Translation Elongation ◽  
Reaction Center Protein ◽  
Membrane Complex ◽  
Global Increase ◽  
Autoregulatory Mechanism

AbstractThe D1 reaction center protein of Photosystem II (PSII) is subject to light-induced damage. Degradation of damaged D1 and its replacement by nascent D1 are at the heart of a PSII repair cycle, without which photosynthesis is inhibited. In mature plant chloroplasts, light stimulates the recruitment of ribosomes specifically to psbA mRNA to provide nascent D1 for PSII repair, and also triggers a global increase in translation elongation rate. The light-induced signals that initiate these responses are unclear. We present action spectrum and genetic data indicating that the light-induced recruitment of ribosomes to psbA mRNA is triggered by D1 photodamage, whereas the global stimulation of translation elongation is triggered by photosynthetic electron transport. Furthermore, mutants lacking HCF136, which mediates an early step in D1 assembly, exhibit constitutively high psbA ribosome occupancy in the dark, and differ in this way from mutants lacking PSII for other reasons. These results, together with the recent elucidation of a thylakoid membrane complex that functions in PSII assembly, PSII repair and psbA translation, suggest an autoregulatory mechanism in which the light-induced degradation of D1 relieves repressive interactions between D1 and translational activators in the complex. We suggest that the presence of D1 in this complex coordinates D1 synthesis with the need for nascent D1 during both PSII biogenesis and PSII repair in plant chloroplasts.Significance StatementPhotosystem II (PSII) harbors the water-splitting activity underlying oxygenic photosynthesis. The PSII reaction center protein D1 is subject to photodamage and must be replaced with nascent D1 to maintain photosynthetic activity. How new D1 synthesis is coordinated with D1 damage has been a long-standing question. Our results clarify the nature of the light-induced signal that activates D1 synthesis for PSII repair in plants, and suggest an autoregulatory mechanism in which degradation of damaged D1 relieves a repressive interaction between D1 and translational activators in a complex that functions in PSII assembly and repair. This proposed mechanism comprises a responsive switch that couples D1 synthesis to need for D1 during PSII biogenesis and repair.

scholarly journals Metamitron, a Photosynthetic Electron Transport Chain Inhibitor, Modulates the Photoprotective Mechanism of Apple Trees

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2803
Author(s):  
Yuval Tadmor ◽  
Amir Raz ◽  
Shira Reikin-Barak ◽  
Vivek Ambastha ◽  
Eli Shemesh ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosynthetic Electron Transport ◽  
State Transitions ◽  
Transport Chain ◽  
Commercial Markets ◽  
Golden Delicious ◽  
Apple Cultivars ◽  
Kinetics Of ◽  
Photosystem Ii Repair ◽  
Repair Cycle

Chemical thinning of apple fruitlets is an important practice as it reduces the natural fruit load and, therefore, increases the size of the final fruit for commercial markets. In apples, one chemical thinner used is Metamitron, which is sold as the commercial product Brevis® (Adama, Israel). This thinner inhibits the electron transfer between Photosystem II and Quinone-a within light reactions of photosynthesis. In this study, we investigated the responses of two apple cultivars—Golden Delicious and Top Red—and photosynthetic light reactions after administration of Brevis®. The analysis revealed that the presence of the inhibitor affects both cultivars’ energetic status. The kinetics of the photoprotective mechanism’s sub-processes are attenuated in both cultivars, but this seems more severe in the Top Red cultivar. State transitions of the antenna and Photosystem II repair cycle are decreased substantially when the Metamitron concentration is above 0.6% in the Top Red cultivar but not in the Golden Delicious cultivar. These attenuations result from a biased absorbed energy distribution between photochemistry and photoprotection pathways in the two cultivars. We suggest that Metamitron inadvertently interacts with photoprotective mechanism-related enzymes in chloroplasts of apple tree leaves. Specifically, we hypothesize that it may interact with the kinases responsible for the induction of state transitions and the Photosystem II repair cycle.

scholarly journals The Role of Selected Wavelengths of Light in the Activity of Photosystem II in Gloeobacter violaceus

2021 ◽  
Vol 22 (8) ◽  
pp. 4021
Author(s):  
Monika Kula-Maximenko ◽  
Kamil Jan Zieliński ◽  
Ireneusz Ślesak
Keyword(s):  
Photosystem Ii ◽  
Spectral Composition ◽  
Photosynthetic Electron Transport ◽  
Metabolic Energy ◽  
Light Conditions ◽  
Gloeobacter Violaceus ◽  
Transport Chain ◽  
Cyanobacterial Culture ◽  
Photosynthetic Antennas

Gloeobacter violaceus is a cyanobacteria species with a lack of thylakoids, while photosynthetic antennas, i.e., phycobilisomes (PBSs), photosystem II (PSII), and I (PSI), are located in the cytoplasmic membrane. We verified the hypothesis that blue–red (BR) light supplemented with a far-red (FR), ultraviolet A (UVA), and green (G) light can affect the photosynthetic electron transport chain in PSII and explain the differences in the growth of the G. violaceus culture. The cyanobacteria were cultured under different light conditions. The largest increase in G. violaceus biomass was observed only under BR + FR and BR + G light. Moreover, the shape of the G. violaceus cells was modified by the spectrum with the addition of G light. Furthermore, it was found that both the spectral composition of light and age of the cyanobacterial culture affect the different content of phycobiliproteins in the photosynthetic antennas (PBS). Most likely, in cells grown under light conditions with the addition of FR and G light, the average antenna size increased due to the inactivation of some reaction centers in PSII. Moreover, the role of PSI and gloeorhodopsin as supplementary sources of metabolic energy in the G. violaceus growth is discussed.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

scholarly journals Revisiting the photosystem II repair cycle

2016 ◽  
Vol 11 (9) ◽  
pp. e1218587 ◽  
Author(s):  
Jasmine Theis ◽  
Michael Schroda
Keyword(s):  
Photosystem Ii ◽  
Photosystem Ii Repair ◽  
Repair Cycle

scholarly journals Cleavage after residue Ala352 in the C-terminal extension is an early step in the maturation of the D1 subunit of Photosystem II in Synechocystis PCC 6803

2007 ◽  
Vol 1767 (6) ◽  
pp. 829-837 ◽  
Author(s):  
Josef Komenda ◽  
Stanislava Kuviková ◽  
Bernhard Granvogl ◽  
Lutz A. Eichacker ◽  
Bruce A. Diner ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Synechocystis Pcc 6803 ◽  
Early Step ◽  
Pcc 6803

Effect of Magnesium and Calcium Ions on the Photoelectron Transport Activity of Low-Salt Suspended Hydrilla verticillata Thylakoids: Possible Sites of Cation Interaction

1998 ◽  
Vol 53 (9-10) ◽  
pp. 849-856
Author(s):  
Sujata R. Mishra ◽  
Surendra Chandra Sabat
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Donor ◽  
Water Oxidation ◽  
Electron Flow ◽  
Hydrilla Verticillata ◽  
Transport Activity ◽  
Low Salt ◽  
Electron Transport Activity ◽  
Stimulation Of

Stimulatory effect of divalent cations like calcium (Ca2+) and magnesium (Mg2+) was investigated on electron transport activity of divalent cation deficient low-salt suspended (LS) thylakoid preparation from a submerged aquatic angiosperm, Hydrilla verticillata. Both the cations stimulated electron transport activity of LS-suspended thylakoids having an intact water oxidation complex. But in hydroxylamine (NH2OH) - or alkaline Tris - washed thylakoid preparations (with the water oxidation enzyme impaired), only Ca2+ dependent stimulation of electron transport activity was found. The apparent Km of Ca2+ dependent stimulation of electron flow from H2O (endogenous) or from artificial electron donor (exogenous) to dichlorophenol indophenol (acceptor) was found to be identical. Calcium supported stimulation of electron transport activity in NH2OH - or Tris - washed thylakoids was electron donor selective, i.e., Ca2+ ion was only effective in electron flow with diphenylcarbazide but not with NH2OH as electron donor to photosystem II. A magnesium effect was observed in thylakoids having an intact water oxidation complex and the ion became unacceptable in NH2OH - or Tris - washed thylakoids. Indirect experimental evidences have been presented to suggest that Mg2+ interacts with the water oxidation complex, while the Ca2+ interaction is localized betw een Yz and reaction center of photosystem II.

Desensitization and resensitization of lutropin receptors expressed in transfected Y-1 adrenal cells

1999 ◽  
Vol 163 (2) ◽  
pp. 289-297 ◽  
Author(s):  
GA Ulaner ◽  
J Chuang ◽  
W Lin ◽  
D Woodbury ◽  
RV Myers ◽  
...  
Keyword(s):  
Receptor Occupancy ◽  
Untranslated Regions ◽  
Protein Synthesis Inhibitor ◽  
Receptor Recycling ◽  
Synthesis Inhibitor ◽  
Early Step ◽  
Hormonal Stimulation ◽  
Adrenal Cells ◽  
Metallothionein Promoter ◽  
Stimulation Of

Stimulation of gonadal cells by lutropins such as human chorionic gonadotropin (hCG) is often transient and followed by down-regulation and/or desensitization of lutropin receptors (LHR). Here we describe desensitization/resensitization of LHR in Y-1 adrenal cell lines (termed Y-1L) expressing a rat cDNA lacking most 5' and 3' LHR untranslated regions under the control of a metallothionein promoter. Using a simple morphological assay in which stimulated cells are round and unstimulated cells are flat, we identified clones that rounded and remained round and others that became insensitive to lutropin stimulation and reverted to their flat appearance within 2-4 h. Flattened cells were insensitive to further hormonal stimulation but rounded after treatments with cholera toxin, forskolin, or cyclic AMP, showing that loss of responsiveness was associated with an early step in signal transduction, not loss of rounding potential. Removing the lutropin stimulus for at least 90-120 min reversed hormone insensitivity, even in the presence of the protein synthesis inhibitor puromycin. The number of surface bound receptors did not change during a cycle of rounding/flattening and hCG bound to rounded or flattened cells was replaced equally by radioiodinated hCG during incubations at 4 degrees C. Thus, desensitization/resensitization of LHR in Y-1L cells occurred in the absence of new receptor synthesis, receptor degradation, or receptor recycling. These observations suggest that LHR desensitization/resensitization in Y-1L cells was closely coupled to receptor occupancy and that this cell line may be useful for identifying factors that modulate the activities of occupied receptors.

Sign in / Sign up

Export Citation Format

Share Document