The role of cytochrome b559 and tyrosineD in protection against photoinhibition during in vivo photoactivation of Photosystem II
(1999) In Biochimica et Biophysica Acta - Bioenergetics 1411(1). p.180-191- Abstract
- In vivo photoactivation of Photosystem II was studied in the FUD39 mutant strain of the green alga Chlamydomonas reinhardtii which lacks the 23 kDa protein subunit involved in water oxidation. Dark grown cells, devoid of oxygen evolution, were illuminated at 0.8 μE m-2&#;s-1 light intensity which promotes optimal activation of oxygen evolution, or at 17 μE m-2&#;s-1, where photoactivation compete with deleterious photodamage. The involvement of the two redox active cofactors tyrosineD and cytochrome b559 during the photoactivation process, was investigated by EPR spectroscopy. TyrosineD on the D2 reaction center protein functions as auxiliary electron donor to the primary donor P680+ during the first minutes of photoactivation at... (More)
- In vivo photoactivation of Photosystem II was studied in the FUD39 mutant strain of the green alga Chlamydomonas reinhardtii which lacks the 23 kDa protein subunit involved in water oxidation. Dark grown cells, devoid of oxygen evolution, were illuminated at 0.8 μE m-2&#;s-1 light intensity which promotes optimal activation of oxygen evolution, or at 17 μE m-2&#;s-1, where photoactivation compete with deleterious photodamage. The involvement of the two redox active cofactors tyrosineD and cytochrome b559 during the photoactivation process, was investigated by EPR spectroscopy. TyrosineD on the D2 reaction center protein functions as auxiliary electron donor to the primary donor P680+ during the first minutes of photoactivation at 0.8 μE m-2&#;s-1 (compare with Rova et al., Biochemistry, 37 (1998) 11039-11045.). Here we show that also cytochrome b559 was rapidly oxidized during the first 10 min of photoactivation with a similar rate to tyrosineD. This implies that both cytochrome b559 and tyrosineD may function as auxiliary electron donors to P680+ and/or the oxidized tyrosine&#;Z on the D1 protein, to avoid photoinhibition before successful photoactivation was accomplished. As the catalytic water-oxidation successively became activated, TyrosineD remained oxidized while cytochrome b559 became rereduced to the equilibrium level that was observed prior to photoactivation. At 17 μE m-2&#;s-1 light intensity, where photoinhibition competes significantly with photoactivation, tyrosineD was very rapidly completely oxidized, after which the amount of oxidized tyrosineD decreased due to photoinhibition. In contrast, cytochrome b559 became reduced during the first 2 min of photoactivation at 17 μE m-2&#;s-1. After this, it was reoxidized, returning to the equilibrium level within 10 min. Thus, during in vivo photoactivation in high-light cytochrome b559 serves two functions. Initially, it probably oxidizes the reduced primary acceptor pheophytin, thereby relieving the acceptor side of reductive pressure, and later on it serves as auxiliary electron donor, preventing donor-side photoinhibition. (Less)
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https://lup.lub.lu.se/record/125358
- author
- Magnusson, Ann ; Rova, Maria ; Mamedov, Fikret LU ; Fredriksson, Per-Olof and Styring, Stenbjörn LU
- organization
- publishing date
- 1999
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Biochimica et Biophysica Acta - Bioenergetics
- volume
- 1411
- issue
- 1
- pages
- 180 - 191
- publisher
- Elsevier
- external identifiers
-
- scopus:0032910596
- ISSN
- 0005-2728
- DOI
- 10.1016/S0005-2728(99)00044-4
- language
- English
- LU publication?
- yes
- id
- 05cd73e4-4947-4f92-81f3-0d8ae9fa2fa2 (old id 125358)
- date added to LUP
- 2016-04-01 17:10:15
- date last changed
- 2022-01-29 00:50:06
@article{05cd73e4-4947-4f92-81f3-0d8ae9fa2fa2,
abstract = {{In vivo photoactivation of Photosystem II was studied in the FUD39 mutant strain of the green alga Chlamydomonas reinhardtii which lacks the 23 kDa protein subunit involved in water oxidation. Dark grown cells, devoid of oxygen evolution, were illuminated at 0.8 μE m-2&#;s-1 light intensity which promotes optimal activation of oxygen evolution, or at 17 μE m-2&#;s-1, where photoactivation compete with deleterious photodamage. The involvement of the two redox active cofactors tyrosineD and cytochrome b559 during the photoactivation process, was investigated by EPR spectroscopy. TyrosineD on the D2 reaction center protein functions as auxiliary electron donor to the primary donor P680+ during the first minutes of photoactivation at 0.8 μE m-2&#;s-1 (compare with Rova et al., Biochemistry, 37 (1998) 11039-11045.). Here we show that also cytochrome b559 was rapidly oxidized during the first 10 min of photoactivation with a similar rate to tyrosineD. This implies that both cytochrome b559 and tyrosineD may function as auxiliary electron donors to P680+ and/or the oxidized tyrosine&#;Z on the D1 protein, to avoid photoinhibition before successful photoactivation was accomplished. As the catalytic water-oxidation successively became activated, TyrosineD remained oxidized while cytochrome b559 became rereduced to the equilibrium level that was observed prior to photoactivation. At 17 μE m-2&#;s-1 light intensity, where photoinhibition competes significantly with photoactivation, tyrosineD was very rapidly completely oxidized, after which the amount of oxidized tyrosineD decreased due to photoinhibition. In contrast, cytochrome b559 became reduced during the first 2 min of photoactivation at 17 μE m-2&#;s-1. After this, it was reoxidized, returning to the equilibrium level within 10 min. Thus, during in vivo photoactivation in high-light cytochrome b559 serves two functions. Initially, it probably oxidizes the reduced primary acceptor pheophytin, thereby relieving the acceptor side of reductive pressure, and later on it serves as auxiliary electron donor, preventing donor-side photoinhibition.}},
author = {{Magnusson, Ann and Rova, Maria and Mamedov, Fikret and Fredriksson, Per-Olof and Styring, Stenbjörn}},
issn = {{0005-2728}},
language = {{eng}},
number = {{1}},
pages = {{180--191}},
publisher = {{Elsevier}},
series = {{Biochimica et Biophysica Acta - Bioenergetics}},
title = {{The role of cytochrome b559 and tyrosineD in protection against photoinhibition during in vivo photoactivation of Photosystem II}},
url = {{http://dx.doi.org/10.1016/S0005-2728(99)00044-4}},
doi = {{10.1016/S0005-2728(99)00044-4}},
volume = {{1411}},
year = {{1999}},
}