Bicarbonate protects the donor side of photosystem II against photoinhibition and thermoinactivation

FEBS Letters

Baranov, S.V¹  Klimov, V.V¹  Allakhverdiev, S.I¹ 

[1]Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow Region 142292, Russia

关键词: Photosystem II;    Bicarbonate;    Photoinhibition;    Thermoinactivation;    BC;    bicarbonate;    PSII;    photosystem II;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    DCPIP;    2;    6-dichlorophenol-indophenol;    ΔF;    photoinduced change of chlorophyll fluorescence yield;    WOC;    water-oxidizing complex of PSII;   

DOI  :  10.1016/S0014-5793(97)01392-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The rate of photoinhibition of photosystem II (PSII) activities (photoinduced change of chlorophyll fluorescence yield, ΔF, and photoreduction of 2,6-dichlorophenol-indophenol) in O₂-evolving pea subchloroplast membrane fragments in medium depleted of CO₂ was considerably decreased upon addition of 5 mM NaHCO₃ before the light treatment. A similar effect was observed when 100 μM MnCl₂ was added before the photoinhibition. In PSII membrane fragments depleted of Mn, the pre-illumination led to irreversible loss of the capability of PSII to be reactivated by Mn²⁺, and the rate of the photoinhibition was decreased by a factor of 2 or 5 if the pre-illumination was done in the presence of 0.2 μM MnCl₂ (≈4 Mn per PSII reaction center) added alone or in combination with 5 mM NaHCO₃, respectively. A similar protective effect of bicarbonate was also revealed in the dark, during thermoinactivation of O₂-evolving PSII at 40°C: the rate of thermoinactivation of ΔF was decreased by a factor of 3 if 5 mM NaHCO₃ was added to the medium. The results are consistent with the idea that bicarbonate is an essential component of the Mn-containing water-oxidizing complex of PSII, which decreases its susceptibility to photoinhibition and thermoinactivation.

【 授权许可】

Unknown