scholarly journals Evidence for thylakoid membrane fusion during zygote formation in Chlamydomonas reinhardtii.

1991 ◽  
Vol 114 (5) ◽  
pp. 905-915 ◽  
Author(s):  
B Baldan ◽  
J Girard-Bascou ◽  
F A Wollman ◽  
J Olive
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Thylakoid Membrane ◽  
De Novo ◽  
Electron Flow ◽  
Thylakoid Membranes ◽  
Structural Basis ◽  
Zygote Formation ◽  
Thin Sections

To understand whether fusions of thylakoid membranes from the parental chloroplasts occurred during zygote formation in Chlamydomonas reinhardtii, we performed an ultrastructural analysis of the zygotes produced by crossing mutants lacking photosystem I or II protein complexes, in the absence of de novo chloroplast protein synthesis. Thylakoid membranes from each parent could be distinguished on thin sections due to their organization in "supergrana" in mutants lacking photosystem I centers, by freeze-fracturing due to the absence of most of the exoplasmic-face (EF) particles in mutants lacking photosystem II centers, by immunocytochemistry using antibodies directed against photosystem II subunits. We demonstrate that a fusion of the thylakoid membranes occurred during zygote formation approximately 15 h after mating. These fusions allowed a lateral redistribution of the thylakoid membrane proteins. These observations provide the structural basis for the restoration of photosynthetic electron flow in the mature zygote that we observed in fluorescence induction experiments.

scholarly journals Differential Changes in the Steady State Levels of Thylakoid Membrane Proteins during Senescence in Cucumis sativus Cotyledons

2001 ◽  
Vol 56 (7-8) ◽  
pp. 585-592 ◽  
Author(s):  
Jogadhenu S. S. Prakash ◽  
Masroor A. Baig ◽  
Prasanna Mohanty
Keyword(s):  
Steady State ◽  
Membrane Proteins ◽  
Photosystem Ii ◽  
Cucumis Sativus ◽  
Photosystem I ◽  
Thylakoid Membrane ◽  
Thylakoid Membranes ◽  
Reaction Centre ◽  
Thylakoid Membrane Proteins ◽  
Steady State Levels

Chloroplast structure and function is known to alter during foliar senescence. Besides, the alterations in the structural organisation of thylakoid membranes changes in the steady state levels of thylakoid membrane proteins occur due to leaf ageing. We monitored temporal changes in some of the specific proteins of thylakoid membrane protein complexes by western blotting in the Cucumis sativus cotyledons as a function of the cotyledon age. We observed that the levels of D1 and D2 proteins of photosystem II started declining at the early stages of senescence of Cucumis cotyledons and continued to decline with the progress of cotyledon age. Similarly the level of Cyt f of Cyt b6/f complex declined rapidly with progress of senescence in these cotyledons. The reaction centre proteins of photosystem I were relatively found to be more stable than that of photosystem II reaction centre proteins reflecting possibly the disorganisation of photosystem II prior to photosystem I. The 33 kDa extrinsic protein (MSP) of oxygen evolving complex, the LHCII apoprotein and the β-subunit of ATPsynthase showed the declined levels with the progress of cotyledon age. However, the extents of loss of these proteins were not as high as the reaction centre proteins of photosystem II and the Cyt f. These results provide that during senescence, proteins of thylakoid membranes degrade in a specific temporal sequence and thereby affect the temporal photo­chemical functions in Cucumis sativus cotyledons

scholarly journals Electron Flow between Photosystem II and Oxygen in Chloroplasts of Photosystem I-deficient Algae Is Mediated by a Quinol Oxidase Involved in Chlororespiration

2000 ◽  
Vol 275 (23) ◽  
pp. 17256-17262 ◽  
Author(s):  
Laurent Cournac ◽  
Kevin Redding ◽  
Jacques Ravenel ◽  
Dominique Rumeau ◽  
Eve-Marie Josse ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Flow ◽  
Quinol Oxidase

scholarly journals A thylakoid membrane-bound and redox-active rubredoxin (RBD1) functions in de novo assembly and repair of photosystem II

2019 ◽  
Vol 116 (33) ◽  
pp. 16631-16640 ◽  
Author(s):  
José G. García-Cerdán ◽  
Ariel L. Furst ◽  
Kent L. McDonald ◽  
Danja Schünemann ◽  
Matthew B. Francis ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membrane ◽  
De Novo Assembly ◽  
Biochemical Characterization ◽  
De Novo ◽  
Midpoint Potential ◽  
Photosynthetic Organisms ◽  
Redox Active ◽  
Photooxidative Damage

Photosystem II (PSII) undergoes frequent photooxidative damage that, if not repaired, impairs photosynthetic activity and growth. How photosynthetic organisms protect vulnerable PSII intermediate complexes during de novo assembly and repair remains poorly understood. Here, we report the genetic and biochemical characterization of chloroplast-located rubredoxin 1 (RBD1), a PSII assembly factor containing a redox-active rubredoxin domain and a single C-terminal transmembrane α-helix (TMH) domain. RBD1 is an integral thylakoid membrane protein that is enriched in stroma lamellae fractions with the rubredoxin domain exposed on the stromal side. RBD1 also interacts with PSII intermediate complexes containing cytochrome b559. Complementation of the Chlamydomonas reinhardtii (hereafter Chlamydomonas) RBD1-deficient 2pac mutant with constructs encoding RBD1 protein truncations and site-directed mutations demonstrated that the TMH domain is essential for de novo PSII assembly, whereas the rubredoxin domain is involved in PSII repair. The rubredoxin domain exhibits a redox midpoint potential of +114 mV and is proficient in 1-electron transfers to a surrogate cytochrome c in vitro. Reduction of oxidized RBD1 is NADPH dependent and can be mediated by ferredoxin-NADP+ reductase (FNR) in vitro. We propose that RBD1 participates, together with the cytochrome b559, in the protection of PSII intermediate complexes from photooxidative damage during de novo assembly and repair. This role of RBD1 is consistent with its evolutionary conservation among photosynthetic organisms and the fact that it is essential in photosynthetic eukaryotes.

DCMU-Induced Fluorescence Changes and Photodestruction of Pigments Associated with an Inhibition of Photosystem I Cyclic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 351-353 ◽  
Author(s):  
Stuart M. Ridley ◽  
Peter Horton
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Dose Response ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic Flow ◽  
Working Hypothesis ◽  
Dose Responses

Diuron (DCMU) induces the photodestruction of pigments, which is the initial herbicidal symptom. As a working hypothesis, it is proposed that this symptom can only be produced when the herbicide dose is sufficiently high to inhibit not only photosystem II electron transport almost completely, but also inhibit (through over oxidation) the natural cyclic electron flow associated with photosystem I as well. Using freshly prepared chloroplasts, studies of DCMU-induced fluorescence changes, and dose responses for inhibition of electron transport, have been compared with a dose response for the photodestruction of pigments in chloroplasts during 24 h illumination. Photodestruction of pigments coincides with the inhibition of cyclic flow.

scholarly journals Chlorophyll triplet states associated with Photosystem I and Photosystem II in thylakoids of the green alga Chlamydomonas reinhardtii

2007 ◽  
Vol 1767 (1) ◽  
pp. 88-105 ◽  
Author(s):  
Stefano Santabarbara ◽  
Giancarlo Agostini ◽  
Anna Paola Casazza ◽  
Christopher D. Syme ◽  
P. Heathcote ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Photosystem I ◽  
Triplet States

scholarly journals Tetratricopeptide repeat protein protects photosystem I from oxidative disruption during assembly

2016 ◽  
Vol 113 (10) ◽  
pp. 2774-2779 ◽  
Author(s):  
Mark Heinnickel ◽  
Rick G. Kim ◽  
Tyler M. Wittkopp ◽  
Wenqiang Yang ◽  
Karim A. Walters ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Thylakoid Membrane ◽  
Redox State ◽  
Tetratricopeptide Repeat ◽  
Wild Type ◽  
Repeat Protein ◽  
Tetratricopeptide Repeat Protein ◽  
History Of

A Chlamydomonas reinhardtii mutant lacking CGL71, a thylakoid membrane protein previously shown to be involved in photosystem I (PSI) accumulation, exhibited photosensitivity and highly reduced abundance of PSI under photoheterotrophic conditions. Remarkably, the PSI content of this mutant declined to nearly undetectable levels under dark, oxic conditions, demonstrating that reduced PSI accumulation in the mutant is not strictly the result of photodamage. Furthermore, PSI returns to nearly wild-type levels when the O2 concentration in the medium is lowered. Overall, our results suggest that the accumulation of PSI in the mutant correlates with the redox state of the stroma rather than photodamage and that CGL71 functions under atmospheric O2 conditions to allow stable assembly of PSI. These findings may reflect the history of the Earth’s atmosphere as it transitioned from anoxic to highly oxic (1–2 billion years ago), a change that required organisms to evolve mechanisms to assist in the assembly and stability of proteins or complexes with O2-sensitive cofactors.

The Effect of Deoxycholate-Treatment to the Photoreactions of the Active Pigments in Photosynthesis

1976 ◽  
Vol 31 (1-2) ◽  
pp. 64-67 ◽  
Author(s):  
Günter Döring
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Electron Flow ◽  
Heavy Fraction ◽  
Sodium Ascorbate ◽  
Linear Electron ◽  
System P ◽  
Heat Treated ◽  
Donor System

Abstract In the heavy fraction of deoxycholate-treated spinach chloroplasts the chlorophyll an activity is high and the chlorophyll aI activity is low when no artificial electron donor is added. The addition of the photosystem I donor system N-methyl-phenazonium sulphate plus sodium ascorbate (PMS + Asc) leads to a complete reactivation of the chlorophyll aI reaction. The addition of the photo­system II donor system p-benzohydroquinone plus sodium ascorbate (HQ + Asc) leads to an inhibition of the chlorophyll aII activity. From these results we conclude: 1. Besides an interruption of the linear electron flow between the two photosystems deoxycholate-treatment leads to a block of the electron flow from water to photosystem II. 2. In deoxycholate-treated chloroplasts the linear electron flow in photosystem II just like in Triswashed, heat-treated or aged chloroplasts, is replaced by a cyclic one.

scholarly journals Photosystem ratio imbalance promotes direct sustainable H2 production in Chlamydomonas reinhardtii

2019 ◽  
Vol 21 (17) ◽  
pp. 4683-4690 ◽  
Author(s):  
Pilla Sankara Krishna ◽  
Stenbjörn Styring ◽  
Fikret Mamedov
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
H2 Production

Changes in the photosystem I/photosystem II ratio promote sustainable H2 production in C. reinhardtii in a standard TAP medium.

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