TY - JOUR
T1 - Electrons generated by photosystem II are utilized by an oxidase in the absence of photosystem I in the cyanobacterium Synechocystis sp. PCC 6803
AU - Vermaas, Wim F.J.
AU - Shen, Gaozhong
AU - Styling, Stenbjörn
N1 - Funding Information:
AcknowledgemenWts.V: . acknowledgeas visitingp rofessorg rantf rom the SwedishN atural ScienceR esearchC ouncil. This work was sup-portedb y researchg rantsf rom the SwedishN aturalS cienceR esearch Council and the Ema and Victor HasselbladF oundation( to S.S.),a nd from the National ScienceF oundation(DMB 90-58279()t o W.V.). This is publication# 172f rom the Arizona StateU niversityC enterf or the Studyo f Early Eventsi n PhotosynthesisT.h e Centeri s fundedb y US Departmento f EnergyG rant DE-FG-88ER13969a s part of the USDA/DOEiNSF Plant ScienceC entersp rogram.
PY - 1994/1/3
Y1 - 1994/1/3
N2 - The reduction and reoxidation kinetics of the first quinone-type electron acceptor in photosystem II, QA-, were measured by fluorescence in a light-tolerant, photosystem I-less strain of the cyanobacterium Synechocystis sp. PCC 6803. In this strain, which shows excellent amplitudes of variable fluorescence, the rate of QA- oxidation after photoreduction of the plastoquinone pool was about half of that in the presence of photosystem I. However, upon addition of 5 mM KCN, QA- decay was very slow, and the rate was comparable to that seen in the presence of diuron, which blocks electron transport between QA and QB. The KCN-imposed block of QA- oxidation was removed efficiently by addition of exogenous quinones that can oxidize the plastoquinone pool. These results indicate that, in the absence of photosystem I, photosystem II-generated electrons are used very effectively by an oxidase located in the thylakoid; this oxidase may be a component of the respiratory chain.
AB - The reduction and reoxidation kinetics of the first quinone-type electron acceptor in photosystem II, QA-, were measured by fluorescence in a light-tolerant, photosystem I-less strain of the cyanobacterium Synechocystis sp. PCC 6803. In this strain, which shows excellent amplitudes of variable fluorescence, the rate of QA- oxidation after photoreduction of the plastoquinone pool was about half of that in the presence of photosystem I. However, upon addition of 5 mM KCN, QA- decay was very slow, and the rate was comparable to that seen in the presence of diuron, which blocks electron transport between QA and QB. The KCN-imposed block of QA- oxidation was removed efficiently by addition of exogenous quinones that can oxidize the plastoquinone pool. These results indicate that, in the absence of photosystem I, photosystem II-generated electrons are used very effectively by an oxidase located in the thylakoid; this oxidase may be a component of the respiratory chain.
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U2 - 10.1016/0014-5793(94)80638-1
DO - 10.1016/0014-5793(94)80638-1
M3 - Article
C2 - 8276100
AN - SCOPUS:0028176092
VL - 337
SP - 103
EP - 108
JO - FEBS Letters
JF - FEBS Letters
SN - 0014-5793
IS - 1
ER -