Iron stress restricts photosynthetic intersystem electron transport in Synechococcus sp. PCC 7942

FEBS Letters

Öquist, G.³  Park, Y.-I.⁴  Huner, N.P.A.¹  Miskiewicz, E.¹  Raven, J.A.²  Ivanov, A.G.¹ 

[1]Department of Plant Sciences, University of Western Ontario, London, Ont., Canada N6A 5B7

[2]Department of Biological Science, University of Dundee, Dundee DD1 4HN, UK

[3]Department of Plant Physiology, University of Umeå, S-901 87 Umeå, Sweden

[4]Department of Biology, Chungnam National University, Taejon 305764, South Korea

关键词: Electron transport;    Iron stress;    Photosystem I;    Synechococcus sp. PCC 7942;    Cyt;    cytochrome;    DBMIB;    2;    5-dibromo-3-methyl-6-isopropyl-p-benzoquinone;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    DCPIP;    2;    6-dichlorophenol-indophenol;    FR;    far red light;    MOPS;    3-[N-morpholino]propanesulfonic acid;    MT;    multiple turnover flash of actinic white light;    MV;    methyl viologen;    P700;    reaction center pigment of PS I;    P700+;    oxidized form of the reaction center of PS I;    PC;    plastocyanin;    PS I;    PS II;    photosystem I and photosystem II;    PQ;    plastoquinone;    Phc;    phycocyanin;    P max;    maximal photosynthetic oxygen evolution;    ST;    single turnover flash of actinic white light;   

DOI  :  10.1016/S0014-5793(00)02211-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Although exposure of Synechococcus sp. PCC 7942 to iron stress induced the accumulation of the isiA gene product (CP43′) compared with non-stressed controls, immunodetection of the N-terminus of cytochrome (Cyt) f indicated that iron stress not only reduced the content of the 40 kDa, heme-binding, Cyt f polypeptide by 32% but it also specifically induced the accumulation of a new, 23 kDa, non-heme-binding, putative Cyt f polypeptide. Concomitantly, iron stress restricted intersystem electron transport based on the in vivo reduction of P700⁺, monitored as ΔA ₈₂₀/A ₈₂₀ in the presence and absence of electron transport inhibitors, as well as the inhibition of the Emerson enhancement effect on O₂ evolution. However, iron stress appeared to be associated with enhanced rates of PS I cyclic electron transport, low rates of PS I-driven photoreduction of NADP⁺ but comparable rates for PS II+PS I photoreduction of NADP⁺ relative to controls. We hypothesize that Synechococcus sp. PCC 7942 exhibits a dynamic capacity to uncouple PS II and PS I electron transport, which may allow for the higher than expected growth rates observed during iron stress.

【 授权许可】

Unknown