Effect of exogenous glucose on the expression and activity of NADPH dehydrogenase complexes in the cyanobacterium Synechocystis sp. strain PCC 6803.
Active NADPH dehydrogenase super- and medium-complexes were newly identified in cyanobacteria and are essential to cyclic photosystem I (PSI) activity and respiration and to CO(2) uptake, respectively. Synechocystis sp. strain PCC 6803 cells were treated with exogenous glucose (Glc) for different times. Active staining of NADPH-nitroblue tetrazolium oxidoreductase and western blot were conducted, and the initial rate of P700(+) dark reduction was measured. The expression and enzyme activity of the NADPH dehydrogenase super-complex were gradually inhibited and were found to be closely associated with the decrease in cyclic PSI activity, as reflected by the initial rate of P700(+) dark reduction. By contrast, those of the NADPH dehydrogenase medium-complex and the activity of CO(2) uptake reflected by the expression levels of NdhD3 and NdhF3 were not significantly affected by the addition of exogenous Glc to the cultures; however, the expression and enzyme activity of this medium-complex were found to be significantly influenced by the changes in CO(2) concentration. These results indicated that (1) the responses of the 2 cyanobacterial NADPH dehydrogenase complexes to exogenous Glc in terms of their expression and activity differed and that (2) these responses were closely associated with their respective physiological roles.
Ma
Weimin
W
College of Life and Environment Sciences, Shanghai Normal University, Guilin Road 100, Shanghai, China.
Mi
Hualing
H
D001426:Bacterial Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology*; D009252:NADPH Dehydrogenase / Q000378:metabolism*; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D045331:Photosystem I Protein Complex / Q000378:metabolism; D046939:Synechocystis / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D020524:Thylakoids / Q000201:enzymology / Q000378:metabolism
D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D002245:Carbon Dioxide; D009252:NADPH Dehydrogenase; D005947:Glucose