scholarly journals Synthesis and assembly of thylakoid protein complexes: multiple assembly steps of photosystem II

2005 ◽  
Vol 388 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Anne ROKKA ◽  
Marjaana SUORSA ◽  
Ammar SALEEM ◽  
Natalia BATTCHIKOVA ◽  
Eva-Mari ARO
Keyword(s):  
Photosystem Ii ◽  
Molecular Mass ◽  
Spinacia Oleracea ◽  
Protein Complexes ◽  
D1 Protein ◽  
Oxygen Evolving Complex ◽  
Reaction Centre ◽  
Light Intensities ◽  
Thylakoid Protein

To study the synthesis and assembly of multisubunit thylakoid protein complexes, we performed [35S]Met pulse and chase experiments with isolated chloroplasts and intact leaves of spinach (Spinacia oleracea L.), followed by Blue Native gel separation of the (sub)complexes and subsequent identification of the newly synthesized and assembled protein subunits. PSII (photosystem II) core subunits were the most intensively synthesized proteins, particularly in vitro and at high light intensities in vivo, and could be sequestered in several distinct PSII subassemblies. Newly synthesized D1 was first found in the reaction centre complex that also contained labelled D2 and two labelled low-molecular-mass proteins. The next biggest PSII subassembly contained CP47 also. Then PsbH was assembled together with at least two other labelled chloroplast-encoded low-molecular-mass subunits, PsbM and PsbTc, and a nuclear-encoded PsbR. Subsequently, CP43 was inserted into the PSII complex concomitantly with PsbK. These assembly steps seemed to be essential for the dimerization of PSII core monomers. Intact PSII core monomer was the smallest subcomplex harbouring the newly synthesized 33 kDa oxygen-evolving complex protein PsbO. Nuclear-encoded PsbW was synthesized only at low light intensities concomitantly with Lhcb polypeptides and was distinctively present in PSII–LHCII (where LHC stands for light-harvesting complex) supercomplexes. The PsbH protein, on the contrary, was vigorously synthesized and incorporated into PSII core monomers together with the D1 protein, suggesting an intrinsic role for PsbH in the photoinhibition-repair cycle of PSII.

scholarly journals Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

2021 ◽  
Vol 7 (9) ◽  
pp. 131
Author(s):  
Maria Chrysina ◽  
Georgia Zahariou ◽  
Nikolaos Ioannidis ◽  
Yiannis Sanakis ◽  
George Mitrikas
Keyword(s):  
Electronic Structure ◽  
Photosystem Ii ◽  
Water Oxidation ◽  
Spinacia Oleracea ◽  
Higher Plants ◽  
Correlation Spectroscopy ◽  
Oxygen Evolving Complex ◽  
Higher Plant ◽  
Proton Coupled Electron Transfer ◽  
S Oxidation

The biological water oxidation takes place in Photosystem II (PSII), a multi-subunit protein located in thylakoid membranes of higher plant chloroplasts and cyanobacteria. The catalytic site of PSII is a Mn4Ca cluster and is known as the oxygen evolving complex (OEC) of PSII. Two tyrosine residues D1-Tyr161 (YZ) and D2-Tyr160 (YD) are symmetrically placed in the two core subunits D1 and D2 and participate in proton coupled electron transfer reactions. YZ of PSII is near the OEC and mediates electron coupled proton transfer from Mn4Ca to the photooxidizable chlorophyll species P680+. YD does not directly interact with OEC, but is crucial for modulating the various S oxidation states of the OEC. In PSII from higher plants the environment of YD• radical has been extensively characterized only in spinach (Spinacia oleracea) Mn- depleted non functional PSII membranes. Here, we present a 2D-HYSCORE investigation in functional PSII of spinach to determine the electronic structure of YD• radical. The hyperfine couplings of the protons that interact with the YD• radical are determined and the relevant assignment is provided. A discussion on the similarities and differences between the present results and the results from studies performed in non functional PSII membranes from higher plants and PSII preparations from other organisms is given.

scholarly journals Two Quenchers Formed During Photodamage of Phostosystem II and The Role of One Quencher in Preemptive Photoprotection

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Alonso Zavafer ◽  
Ievgeniia Iermak ◽  
Mun Hon Cheah ◽  
Wah Soon Chow
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Time Course ◽  
Physiological Role ◽  
Reaction Centre ◽  
Time Resolved ◽  
Fluorescence Quencher

AbstractThe quenching of chlorophyll fluorescence caused by photodamage of Photosystem II (qI) is a well recognized phenomenon, where the nature and physiological role of which are still debatable. Paradoxically, photodamage to the reaction centre of Photosystem II is supposed to be alleviated by excitation quenching mechanisms which manifest as fluorescence quenchers. Here we investigated the time course of PSII photodamage in vivo and in vitro and that of picosecond time-resolved chlorophyll fluorescence (quencher formation). Two long-lived fluorescence quenching processes during photodamage were observed and were formed at different speeds. The slow-developing quenching process exhibited a time course similar to that of the accumulation of photodamaged PSII, while the fast-developing process took place faster than the light-induced PSII damage. We attribute the slow process to the accumulation of photodamaged PSII and the fast process to an independent quenching mechanism that precedes PSII photodamage and that alleviates the inactivation of the PSII reaction centre.

scholarly journals The Arabidopsis PsbO2 protein regulates dephosphorylation and turnover of the photosystem II reaction centre D1 protein

2007 ◽  
Vol 49 (3) ◽  
pp. 528-539 ◽  
Author(s):  
Björn Lundin ◽  
Maria Hansson ◽  
Benoît Schoefs ◽  
Alexander V. Vener ◽  
Cornelia Spetea
Keyword(s):  
Photosystem Ii ◽  
D1 Protein ◽  
Reaction Centre

scholarly journals The effects of high concentrations of salts on photosynthetic electron transport in spinach (Spinacia oleracea) chloroplasts

1982 ◽  
Vol 204 (3) ◽  
pp. 705-712 ◽  
Author(s):  
A C Stewart
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Spinacia Oleracea ◽  
Photosynthetic Electron Transport ◽  
Potassium Citrate ◽  
O2 Evolution ◽  
Hofmeister Series ◽  
Reaction Centre ◽  
High Concentrations

1. Photosynthetic electron transport from water to lipophilic Photosystem II acceptors was stimulated 3-5-fold by high concentrations (greater than or equal to 1 M) of salts containing anions such as citrate, succinate and phosphate that are high in the Hofmeister series. 2. In trypsin-treated chloroplasts, K3Fe(CN)6 reduction insensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea was strongly stimulated by high concentrations of potassium citrate, but there was much less stimulation of 2,6-dichloroindophenol reduction in Tris-treated chloroplasts supplied with 1,5-diphenylcarbazide as artificial donor. The results suggest that the main site of action of citrate was the O2-evolving complex of Photosystem II. 3. Photosystem I partial reactions were also stimulated by intermediate concentrations of citrate (up to 2-fold stimulation by 0.6-0.8 M-citrate), but were inhibited at the highest concentrations. The observed stimulation may have been caused by stabilizaton of plastocyanin that was complexed with the Photosystem I reaction centre, 4. At 1 M, potassium citrate protected O2 evolution against denaturation by heat or by the chaotropic agent NaNO3. 5. It is suggested that anions high in the Hofmeister series stimulated and stabilized electron transport by enhancing water structure around the protein complexes in the thylakoid membrane.

Sign in / Sign up

Export Citation Format

Share Document