Chlorophyll—protein complexes related to photosystem I in Chlamydomonas reinhardtii

1989 ◽  
Vol 4 (1) ◽  
pp. 97-109 ◽  
Author(s):  
Jeannine Maroc ◽  
Jacques Garnier ◽  
Denise Guyon
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Protein Complexes ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

scholarly journals A chlorophyll-protein complex lacking in photosystem I mutants of Chlamydomonas reinhardtii.

1975 ◽  
Vol 67 (2) ◽  
pp. 361-377 ◽  
Author(s):  
N H Chua ◽  
K Matlin ◽  
P Bennoun
Keyword(s):  
Molecular Weight ◽  
Chlamydomonas Reinhardtii ◽  
Photosystem I ◽  
Protein Complex ◽  
Protein Complexes ◽  
Sodium Dodecyl ◽  
Weight Ratio ◽  
Thylakoid Membranes ◽  
Higher Plant ◽  
Chlorophyll Protein

Sodium dodecyl sulfate gel electrophoresis of unheated, detergent-solubilized thylakoid membranes of Chlamydomonas reinhardtii gives two chlorophyll-protein complexes. Chlorophyll-protein complex I (CP I) is the blue-green in color and can be dissociated by heat into "free" chlorophyll and a constituent polypeptide (polypeptide 2; mol wt 66,000). Similar experiments with spinach and Chinese cabbage show that the higher plant CP I contains an equivalent polypeptide but of slightly lower molecular weight (64,000). Both polypeptide 2 and its counterpart in spinach are soluble in a 2:1 (vol/vol) mixture of chloroform-methanol. Chemical analysis reveals that C. reinhardtii CP I has a chlorophyll a to b weight ratio of about 5 and that it contains approximately 5% of the total chlorophyll and 8-9% of the total protein of the thylakoid membranes. Thus, it can be calculated that each constituent polypeptide chain is associated with eight to nine chlorophyll molecules. Attempts to measure the molecular weight of CP I by calibrated SDS gels were unsuccessul since the complex migrates anomalously in such gels. Two Mendelian mutants of C. reinhardtii, F1 and F14, which lack P700 but have normal photosystem I activity, do not contain CP I or the 66,000-dalton polypeptide in their thylakoid membranes. Our results suggest that CP I is essential for photosystem I reaction center activity and that P700 may be associated with the 66,000-dalton polypeptide.

scholarly journals Impaired respiration discloses the physiological significance of state transitions in Chlamydomonas

2009 ◽  
Vol 106 (37) ◽  
pp. 15979-15984 ◽  
Author(s):  
Pierre Cardol ◽  
Jean Alric ◽  
Jacqueline Girard-Bascou ◽  
Fabrice Franck ◽  
Francis-André Wollman ◽  
...  
Keyword(s):  
Photosystem I ◽  
Photosynthetic Activity ◽  
Protein Complexes ◽  
Carbon Assimilation ◽  
Physiological Significance ◽  
State Transitions ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein ◽  
Redox Poise ◽  
Electron Carriers

State transitions correspond to a major regulation process for photosynthesis, whereby chlorophyll protein complexes responsible for light harvesting migrate between photosystem II and photosystem I in response to changes in the redox poise of the intersystem electron carriers. Here we disclose their physiological significance in Chlamydomonas reinhardtii using a genetic approach. Using single and double mutants defective for state transitions and/or mitochondrial respiration, we show that photosynthetic growth, and therefore biomass production, critically depends on state transitions in respiratory-defective conditions. When extra ATP cannot be provided by respiration, enhanced photosystem I turnover elicited by transition to state 2 is required for photosynthetic activity. Concomitant impairment of state transitions and respiration decreases the overall yield of photosynthesis, ultimately leading to reduced fitness. We thus provide experimental evidence that the combined energetic contributions of state transitions and respiration are required for efficient carbon assimilation in this alga.

scholarly journals Structural changes and lateral redistribution of photosystem II during donor side photoinhibition of thylakoids.

1992 ◽  
Vol 119 (2) ◽  
pp. 325-335 ◽  
Author(s):  
R Barbato ◽  
G Friso ◽  
F Rigoni ◽  
F Dalla Vecchia ◽  
G M Giacometti
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Structural Changes ◽  
Protein Complexes ◽  
Gradient Centrifugation ◽  
Photosynthetic Apparatus ◽  
Topological Stability ◽  
Donor Side ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

The structural and topological stability of thylakoid components under photoinhibitory conditions (4,500 microE.m-2.s-1 white light) was studied on Mn depleted thylakoids isolated from spinach leaves. After various exposures to photoinhibitory light, the chlorophyll-protein complexes of both photosystems I and II were separated by sucrose gradient centrifugation and analysed by Western blotting, using a set of polyclonals raised against various apoproteins of the photosynthetic apparatus. A series of events occurring during donor side photoinhibition are described for photosystem II, including: (a) lowering of the oligomerization state of the photosystem II core; (b) cleavage of 32-kD protein D1 at specific sites; (c) dissociation of chlorophyll-protein CP43 from the photosystem II core; and (d) migration of damaged photosystem II components from the grana to the stroma lamellae. A tentative scheme for the succession of these events is illustrated. Some effects of photoinhibition on photosystem I are also reported involving dissociation of antenna chlorophyll-proteins LHCI from the photosystem I reaction center.

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