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Physiological Role of pH-Dependent Structural Transition in Oxygen-Evolving Complex of PSIIстатья
- Авторы: Semin B.K., Davletshina L.N., Loktyushkin A.V., Lovyagina E.R.
- Журнал: Russian Journal of Plant Physiology
- Том: 70
- Номер: 1
- Год издания: 2023
- Издательство: Maik Nauka/Interperiodica Publishing
- Местоположение издательства: Russian Federation
- DOI: 10.1134/S1021443722700017
- Аннотация: Photosystem II (PSII) of the photosynthetic apparatus in oxygenic organisms contains a catalyticcenter that performs one of the most important reactions in bioenergetics: light-dependent water oxidation tomolecular oxygen. The catalytic center is a Mn4 CaO 5 cluster consisting of four cations of manganese and onecalcium cation linked by oxygen bridges. The authors reported earlier that a structural transition occurs atpH 5.7 in the cluster resulting in changes in manganese cation(s) redox potential and elevation of theMn-cluster resistance to reducing agents. The discovered effect was examined in a series of investigations thatare reviewed in this work. It was found that, at pH 5.7, Fe(II) cations replace not two manganese cations as ithappens at pH 6.5 but only one cation; as a result, a chimeric Mn3 Fe 1 cluster is produced. In the presence ofexogenous calcium ions, membrane preparations of PSII with such a chimeric cluster are capable of evolvingoxygen in the light (at a rate of approximately 25% of the rate in native PSII). It was found that photoinhibi-tion that greatly depends on the processes of oxidation or reduction at pH 5.7 slows down as compared withpH 6.5. PSII preparations were also more resistant to thermal inactivation at pH 5.7 than at pH 6.5. However,in PSII preparations lacking manganese cations in the oxygen-evolving complex, the rates of photoinhibitionat pH 6.5 and 5.7 did not differ. In thylakoid membranes, protonophores that abolish the proton gradient andincrease pH in the lumen (where the manganese cluster is located) from 5.7 to 7.0 considerably elevated therate of PSII photoinhibition. It is assumed that the structural transition in the Mn-cluster at pH 5.7 isinvolved in the mechanisms of PSII defense against photoinhibition.
- Добавил в систему: Ловягина Елена Рудольфовна
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | Russ_J_Plant_Physiol_2023.pdf | Russ_J_Plant_Physiol_2023.pdf | 1,1 МБ | 26 ноября 2023 [Elena.Lovyagina] |