scholarly journals Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow

2016 ◽  
Vol 171 (1) ◽  
pp. 530-541 ◽  
Author(s):  
Yaqi Sun ◽  
Selene Casella ◽  
Yi Fang ◽  
Fang Huang ◽  
Matthew Faulkner ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Electron Flow ◽  
Photosynthetic Electron Flow

Effects of endogenous ascorbic acid on the distribution of photosynthetic electron flow in rice leaves

2019 ◽  
Vol 70 (10) ◽  
pp. 849
Author(s):  
Qilei Zhang ◽  
Minling Cai ◽  
Lina Lu ◽  
Hui Gao ◽  
Changlian Peng
Keyword(s):  
Ascorbic Acid ◽  
Photosynthetic Rate ◽  
Carbon Fixation ◽  
Higher Plants ◽  
Rice Yield ◽  
Oryza Sativa L ◽  
Electron Flow ◽  
Wild Type ◽  
Photosynthetic Electron Flow ◽  
Rice Leaves

Ascorbic acid (Asc) is one of the major antioxidants in plants. l-Galactono-1,4-lactone dehydrogenase (GLDH) is an enzyme that catalyses the last step of Asc biosynthesis in higher plants. In this study the effects of endogenous Asc on the distribution of photosynthetic electron flow were investigated in wild-type (ZH-11) rice (Oryza sativa L.) and in GLDH-overexpressing (GO-2) and GLDH-suppressed (GI-2) transgenic rice. The ratio of photosynthetic electron flow distributed to Rubisco-dependent carboxylation was highest in GO-2, whereas other electron flows in addition to carbon fixation were highest in GI-2 after flowering. Further examination showed that the photosynthetic electron flow, GLDH content and reactive oxygen species-scavenging ability were highest in GO-2 and lowest in GI-2. Therefore, the senescence of leaves was faster in GI-2 but slower in GO-2 compared with ZH-11. In addition, leaves with higher Asc content had more Rubisco content and a superior photosynthetic rate, which increased rice yield. These results suggest that increasing the endogenous Asc content of rice delays senescence, maintains a higher photosynthetic rate and results in more photosynthetic electron flow distributed to Rubisco-dependent carboxylation, ultimately leading to increased rice yield.

scholarly journals High-Resolution Crystal Structure of Chloroplastic Ribose-5-Phosphate Isomerase from Chlamydomonas reinhardtii—An Enzyme Involved in the Photosynthetic Calvin-Benson Cycle

2020 ◽  
Vol 21 (20) ◽  
pp. 7787
Author(s):  
Théo Le Moigne ◽  
Pierre Crozet ◽  
Stéphane D. Lemaire ◽  
Julien Henri
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Metabolic Pathway ◽  
Carbon Fixation ◽  
Electron Flow ◽  
Structural Data ◽  
Post Translational Modifications ◽  
Photosynthetic Electron Flow ◽  
Biochemical Modeling ◽  
Experimental Structure

The Calvin–Benson cycle is the key metabolic pathway of photosynthesis responsible for carbon fixation and relies on eleven conserved enzymes. Ribose-5-phosphate isomerase (RPI) isomerizes ribose-5-phosphate into ribulose-5-phosphate and contributes to the regeneration of the Rubisco substrate. Plant RPI is the target of diverse post-translational modifications including phosphorylation and thiol-based modifications to presumably adjust its activity to the photosynthetic electron flow. Here, we describe the first experimental structure of a photosynthetic RPI at 1.4 Å resolution. Our structure confirms the composition of the catalytic pocket of the enzyme. We describe the homo-dimeric state of the protein that we observed in the crystal and in solution. We also map the positions of previously reported post-translational modifications and propose mechanisms by which they may impact the catalytic parameters. The structural data will inform the biochemical modeling of photosynthesis.

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.

Non-Invasive Monitoring of the Light-Induced Cyclic Photosynthetic Electron Flow during Cold Hardening in Wheat Leaves

2006 ◽  
Vol 61 (9-10) ◽  
pp. 734-740 ◽  
Author(s):  
Simona Apostol ◽  
Gabriella Szalai ◽  
László Sujbert ◽  
Losanka P. Popova ◽  
Tibor Janda
Keyword(s):  
Winter Wheat ◽  
Electron Flow ◽  
Wheat Variety ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Light Conditions ◽  
Non Invasive ◽  
Photosynthetic Electron Flow ◽  
Temperature Hardening ◽  
Wheat Leaves

AbstractThe effect of irradiance during low temperature hardening was studied in a winter wheat variety. Ten-day-old winter wheat plants were cold-hardened at 5 °C for 11 days under light (250 μmol m-2 s-1) or dark (20 μmol m-2 s-1) conditions. The effectiveness of hardening was significantly lower in the dark, in spite of a slight decrease in the Fv/Fm chlorophyll fluorescence induction parameter, indicating the occurrence of photoinhibition during the hardening period in the light. Hardening in the light caused a downshift in the far-red induced AG (afterglow) thermoluminescence band. The faster dark re-reduction of P700+, monitored by 820-nm absorbance, could also be observed in these plants. These results suggest that the induction of cyclic photosynthetic electron flow may also contribute to the advantage of frost hardening under light conditions in wheat plants.

Antibodies to Chlorophyll and their Reactions with Chloroplast Preparations

1971 ◽  
Vol 26 (5) ◽  
pp. 435-446 ◽  
Author(s):  
Alfons Radunz ◽  
Georg H. Schmid ◽  
Wilhelm Menke
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Membrane Surface ◽  
Protein Composition ◽  
Inhibitory Effect ◽  
Hill Reaction ◽  
Protein Layer ◽  
Lamellar System ◽  
Light Reaction ◽  
Photosynthetic Electron Flow

Antibodies to chlorophyll are specifically adsorbed onto the membrane surface of thylakoids. The antibodies inhibit photosynthetic electron flow from water to NADP⊕. This inhibition is presumably caused by adsorption of the antibodies onto the centre chlorophyll of light reaction II. Fragments of the thylakoid membrane, obtained by ultrasonication and subsequent fractioning centrifugation, exhibit only photosystem-I activity. Conversely, the specific adsorption of antibodies to sensitizer chlorophyll has no inhibitory effect on electron transport. The ferricyanide Hill reaction of chloroplast preparations is inhibited by chlorophyll antibodies. From these observations it is concluded that the centre chlorophyll of light reaction II and at least part of the sensitizer chlorophyll is located on the surface of the thylakoids. As agglutination is sterically inhibited by the membrane protein, it is assumed that the chlorophyll is located in gaps or pores of the protein layer.Two fractions of the lamellar system exhibit photosystem I activity of different characteristic electron donor specificity. These fractions can be further distinguished in terms of their circular dichroism and protein composition.

Formate as an Inhibitor of Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 386-388 ◽  
Author(s):  
Jan F. H. Snel ◽  
Dirk Naber ◽  
Jack J. S. van Rensen
Keyword(s):  
Inhibitory Action ◽  
Electron Flow ◽  
Hill Reaction ◽  
Maximal Inhibition ◽  
Photosynthetic Electron Flow ◽  
The Hill

The effects of formate on the Hill reaction in isolated broken pea chloroplasts were in­vestigated. Addition of formate to chloroplasts has two distinct effects: I. basal electron flow can be stimulated 3-fold; 2. uncoupled electron flow is inhibited. The stimulating effect is due to uncoupling by formate and appears instantaneous. Maximal inhibition by form ate is only observed after prolonged illumination. The inhibitory action of form ate on electron flow can be relieved by bicarbonate *.

Sign in / Sign up

Export Citation Format

Share Document