Nucleotide-CF1 interactions and current views on the catalytic mechanism

The binding of nucleotides on isolated subunits as well as on reconstituted CF1 core complex is reviewed. Nucleotide interaction with CF1 and consequent ATPase activity are always associated with the presence of Mg2+. The metal binding site studies using Electron Paramagnetic Resonance (EPR) and pul...

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Bibliographic Details
Published in:Photosynthesis research 1998-09, Vol.57 (3), p.253-266
Main Authors: Girault, G. (CEA-Saclay, Gif-sur-Yvette (France). Dept. de Biologie Cellulaire et Moleculaire), Berger, G, Zimmermann, J.L
Format: Article
Language:English
Subjects:
ACTIVIDAD CATALITICA
ACTIVITE CATALYTIQUE
ATP
Binding sites
CATALYTIC ACTIVITY
Kinases
NUCLEOTIDE
NUCLEOTIDES
NUCLEOTIDOS
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Summary:The binding of nucleotides on isolated subunits as well as on reconstituted CF1 core complex is reviewed. Nucleotide interaction with CF1 and consequent ATPase activity are always associated with the presence of Mg2+. The metal binding site studies using Electron Paramagnetic Resonance (EPR) and pulsed EPR conclude that the metal binding occurs prior to any nucleotide addition. The addition of nucleotide does not modify the enzyme's metal binding site but brings on additional ligands with the phosphates of the nucleotides. The ATPase and nucleotide binding experiments with CF1 are also better interpreted by the hypothesis that Mg2+ is an activator rather than an inhibitor of the enzyme and that the actual substrate of CF1-ATPase is ATP rather than MgATP. The dual role of tentoxin as an inhibitor at low concentration (10^sup -8^-10^sup -7^ M) and activator at higher concentrations (10^sup -6^ M) of the enzymatic activity of CF1, is due to the presence of two different binding sites on CF1. The synthesis of a new cyclic analogue of tentoxin with alanine changed for a serine has shown that it was possible to dissociate the two roles. The serine tentoxin analogue has the same inhibition effect on CF1 but is no longer an activator. The binding of nucleotides may influence the stability, produce structural changes and, over long distance, cause movements of CF1. All these effects of nucleotide or metal binding and activation or inhibition of CF1 may help also to elucidate the role played by the catalytic and non catalytic sites. These questions are reviewed and analyzed with respect to the current views on the catalytic mechanism.[PUBLICATION ABSTRACT]
ISSN:0166-8595
1573-5079
DOI:10.1023/A:1006034231713