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Title: INVESTIGATING OXYGEN EVOLUTION IN THE ABSENCE OF PHOTOSYSTEM I IN THE CYANOBACTERIUM SYNECHOCYSTIS 68031

Author
item WANG, QINGIUN - BIOPHYSICS UOFI URBANA IL
item WHITMARSH, CLIFFORD

Submitted to: International Congress of Photosynthesis Brisbane Australia
Publication Type: Proceedings
Publication Acceptance Date: 8/25/2001
Publication Date: 12/20/2001
Citation: WANG, Q., WHITMARSH, C.J. Investigating oxygen evolution in the absence of photosyten I in the Cyanobacterium synechocystis 68031. International Congress of Photosynthesis Brisbane Australia. 2001.

Interpretive Summary:

Technical Abstract: Photosynthetic electron transport in plants, algae and cyanobacteria requires the photosystem II reaction center to extract electrons from water and the photosystem I reaction center to promote the electrons to NADP. Thus it is surprising that cyanobacterial mutants that lack photosystem I are able to evolve O2. To determine the pathway of electrons from H2O we are investigating photosystem I-less mutants of Synechocystis 6803. Although none of the mutants are able to grow photoautotrophically, they can sustain high rates of steady state oxygen evolution for more than an hour. The observation that O2 evolution in the mutant cells are sensitive to DCMU establishes photosystem II as the source of molecular oxygen. We have shown that glucose plays a critical role in O2 evolution in the mutants. As glucose is depleted oxygen evolution decreases, whereas the addition of glucose to glucose-starved cells rapidly restores oxygen evolution. This observation raises the possibility that an intermediate of glucose metabolism may serve as an intermediate or terminal electron acceptor.