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Plant Cell Physiol. 2003 May;44(5):534-40.

Effects of low CO2 on NAD(P)H dehydrogenase, a mediator of cyclic electron transport around photosystem I in the cyanobacterium synechocystis PCC6803.

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National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Fenglin Road 300, Shanghai, 200032 China.


The expression and activity of type-1 NAD(P)H dehydrogenase (NDH-1) was compared between cells of Synechocystis PCC6803 grown in high (H-cells) and low (L-cells) CO(2) conditions. Western analysis indicated that L-cells contain higher amounts of the NDH-1 subunits, NdhH, NdhI and NdhK. An NADPH-specific subcomplex of NDH-1 showed higher NADPH-nitroblue tetrazolium oxidoreductase activity in L-cells. The activities of both NADPH-menadione oxidoreductase and light-dependent NADPH oxidation driven by photosystem I were much higher in L-cells than in H-cells. The initial rate of re-reduction of P700(+) following actinic light illumination in the presence of DCMU under background far-red light was enhanced in L-cells. In addition, rotenone, a specific inhibitor of NDH-1, suppressed the relative rate of post-illumination increase in Chl fluorescence of L-cells more than that of H-cells, suggesting that the involvement of NDH-1 in cyclic electron flow around photosystem I was enhanced by low CO(2). Taken together, these results suggest that NDH-1 complex and NDH-1-mediated cyclic electron transport are stimulated by low CO(2) and function in the acclimation of cyanobacteria to low CO(2).

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