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Title: Correlation between changes in light energy distribution and changes in thylakoid membrane polypeptide phosphorylation in Chlamydomonas reinhardtii

Journal Article · · J. Cell Biol.; (United States)
DOI:https://doi.org/10.1083/jcb.98.1.1· OSTI ID:5863013

We have used a new method to extensively modify the redox state of the plastoquinone pool in Chlamydomonas reinhardtii intact cells. This was achieved by an anaerobic treatment that inhibits the chlororespiratory pathway recently described by P. Bennoun. A state I (plus 3,4-dichlorophenyl-1,1-dimethylurea) ..-->.. anaerobic state transition induced a decrease in the maximal fluorescence yield at room temperature and in the F/sub PSII//F/sub PSI/ ratio at 77/sup 0/K, which was three times larger than in a classical state I ..-->.. state II transition. The fluorescence changes observed in vivo were similar in amplitude to those observed in vitro upon transfer to the light of dark-adapted, broken chloroplasts incubated in the presence of ATP. We then compared the phosphorylation pattern of thylakoid polypeptides in C. reinhardtii in vitro and in vivo using ..gamma..-(/sup 32/P)ATP and (/sup 32/P)orthophosphate labeling, respectively. The same set of polypeptides, mainly light-harvesting complex polypeptides, was phosphorylated in both cases. We observed that this phosphorylation process is reversible and is mediated by the redox state of the plastoquinone pool in vivo as well as in vitro. Similar changes of even larger amplitude were observed with the F34 mutant intact cells lacking in photosystem II centers. The presence of the photosystem II centers is then not required for the occurrence of the plastoquinone-mediated phosphorylation of light-harvesting complex polypeptides.

Research Organization:
Institut de Biologie Physico-Chimique, Paris, France
OSTI ID:
5863013
Journal Information:
J. Cell Biol.; (United States), Vol. 98:1
Country of Publication:
United States
Language:
English