Bicarbonate binding and the properties of photosystem II electron acceptors

FEBS Letters

Lockett, Christopher J.¹  Demetriou, Christalla¹  Corrie, Andrew R.¹  Evans, Michael C.W.¹  Nugent, Jonathan H.A.¹ 

[1] Department of Biology, University College London, Darwin Building, Gower Street, London WC1E 6BT, England

关键词: Photosystem II;    ESR;    Bicarbonate;    Herbicide;    Iron-quinone;    Chl;    chlorophyll;    PS II;    photosystem II;    Mes;    4-morpholineethanesulphonic acid;    DCMU;    3-(3;    4-dichloro-phenyl)-1;    1-dimethylurea;    CCCP;    carbonyl cyanide m-chlorophenylhydrazone;    DMBQ;    2;    6-dimethylbenzoquinone;   

DOI  :  10.1016/0014-5793(88)81236-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have investigated the quinone-binding region of PS II using exchange reactions to replace key components. Bicarbonate was replaced by formate and Q_B by exogenous quinones or herbicide. The effects of these changes were monitored using the ESR signals from the Q_A iron-semiquinone and Fe³⁺ non-haem iron components. We observed that Q_B binding caused characteristic changes in the Q⁻ _A ESR signal and confirmed that the characteristics of Q⁻ _A depend on bicarbonate binding. The non-haem iron was oxidised only under conditions where bicarbonate was bound. The characteristics of bicarbonate binding were observed in Phormidium laminosum PS II, showing that the bicarbonate effect occurs in cyanobacteria. The results support a hypothesis which gives a central role to bicarbonate in providing the conditions for electron transfer in both cyanobacteria and higher plant PS II. It is suggested that bicarbonate binds at or close to the non-haem iron and influences the characteristics of Q_A, Q_B and the non-haem iron.

【 授权许可】

Unknown