Skip to Main content Skip to Navigation
Journal articles

Phosphoribulokinase from Chlamydomonas reinhardtii: a Benson–Calvin cycle enzyme enslaved to its cysteine residues

Abstract : Phosphoribulokinase (PRK) in the green alga Chlamydomonas reinhardtii is a finely regulated and well-studied enzyme of the Benson–Calvin cycle. PRK can form a complex with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the small chloroplast protein CP12. This study aimed to determine the molecular determinants on PRK involved in the complex and the mechanism of action of a recently described novel regulation of PRK that involves glutathionylation. A combination of mass spectrometry, mutagenesis and activity analyses showed that Cys16, besides its role as the binding site of ATP, was also the site for S-glutathionylation. Previous kinetic analysis of the C55S mutant showed that in the oxidized inactive form of PRK, this residue formed a disulfide bridge with the Cys16 residue. This is the only bridge reported for PRK in the literature. Our data show for the first time that a disulfide bridge between Cys243 and Cys249 on PRK is required to form the PRK–GAPDH–CP12 complex. These results uncover a new mechanism for the PRK–GAPDH–CP12 formation involving a thiol disulfide exchange reaction with CP12 and identify Cys16 of PRK as a target of glutathionylation acting against oxidative stress. Although Cys16 is the key residue involved in binding ATP and acting as a defense against oxidative damage, the formation of the algal ternary complex requires the formation of another disulfide bridge on PRK involving Cys243 and Cys249.
Document type :
Journal articles
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-01429055
Contributor : Laure Azzopardi <>
Submitted on : Friday, January 6, 2017 - 5:47:24 PM
Last modification on : Tuesday, November 10, 2020 - 3:09:46 AM

Identifiers

Collections

Citation

Gabriel Thieulin Pardo, Therese Remy, Régine Lebrun, Sabrina Lignon, Brigitte Gontero. Phosphoribulokinase from Chlamydomonas reinhardtii: a Benson–Calvin cycle enzyme enslaved to its cysteine residues. Molecular BioSystems, Royal Society of Chemistry, 2015, pp.1134-1145. ⟨10.1039/C5MB00035A⟩. ⟨hal-01429055⟩

Share

Metrics

Record views

183