Abstract
A highly active NADPH dehydrogenase super-complex mediating both cyclic electron flow and respiratory flow was identified in the cyanobacterium Synechocystis sp. strain PCC 6803. Active staining of NADPH-nitroblue tetrazolium oxidoreductase, Western blotting, redox changes of P700, and measurements of respiration were carried out with the cells treated by exogenous glucose (Glc) or 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) at several time points. The expression and enzyme activity levels of this NADPH dehydrogenase supercomplex were gradually inhibited accompanying the addition of exogenous Glc but significantly stimulated in the presence of DCMU. Though PSIdependent cyclic electron transport was decreased in Glc-treated cells, respiration rate was accelerated. Unexpectedly, both cyclic PSI and respiration rate were decreased in the presence of DCMU. Based on the Glc caused the partial reduction of plastoquinone pool while DCMU resulted in the over-oxidation of plastoquinone pool, we suggest that the expression and activity of NADPH dehydrogenase supercomplex is under redox control while the operation of both cyclic and respiratory electron flow mediated by this active super-complex needs an appropriate redox poise of the plastoquinone pool.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
