Correlation between a Conformational Change in the Coupling Factor Protein and the High Energy State in Chloroplasts

Exposure of chloroplasts to a tritiated water solvent resulted in labeling of the coupling factor protein (CF1) concomitant with formation of a phosphorylating state in the membranes; tritium uptake occurred during illumination, acid-base transition, and ATPase activity in chloroplasts, and was larg...

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Bibliographic Details
Published in:The Journal of biological chemistry 1972-07, Vol.247 (14), p.4453-4459
Main Authors: Ryrie, Ivan J., Jagendorf, Andre T.
Format: Article
Language:English
Subjects:
Adenosine Diphosphate - pharmacology
Adenosine Triphosphatases - radiation effects
Chloroplasts - drug effects
Chloroplasts - enzymology
Chloroplasts - radiation effects
Dithiothreitol - pharmacology
Hydrogen-Ion Concentration
Light
Membranes
Oxidative Phosphorylation Coupling Factors
Phlorhizin - pharmacology
Phosphates - pharmacology
Phosphorus Isotopes
Photophosphorylation
Photosynthesis
plant biochemistry
Plant Cells
plant physiology
Plant Proteins - radiation effects
Protein Conformation
Quaternary Ammonium Compounds - pharmacology
Radiation Effects
Tritium
Valinomycin - pharmacology
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Summary:Exposure of chloroplasts to a tritiated water solvent resulted in labeling of the coupling factor protein (CF1) concomitant with formation of a phosphorylating state in the membranes; tritium uptake occurred during illumination, acid-base transition, and ATPase activity in chloroplasts, and was largely abolished by inhibitors which destroy the high energy condition. In digitonin subchloroplast particles, the light-dependent tritiation of CF1 occurred in the presence of NH4Cl. Further addition of valinomycin, which uncouples phosphorylation, largely prevented the labeling. These and previous observations (Ryrie, I. J., and Jagendorf, A. T. (1971) J. Biol. Chem. 246, 3771) are interpreted as evidence for an energy-linked conformational change in CF1. It is suggested that this may be necessary to allow ATP synthesis. Inclusion of ADP and Pi decreased both tritium uptake into CF1 and a light-induced discharge from the previously labeled protein. Apparently, the inhibition was not dependent on ATP synthesis. We conclude that in the presence of substrates, less of the protein matrix is exposed by the conformaional change.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)45006-0