Dynamics of the intrinsically disordered protein CP12 in its association with GAPDH in the green alga Chlamydomonas reinhardtii: a fuzzy complex.
CP12 is a widespread regulatory protein of oxygenic photosynthetic organisms that contributes to the regulation of the Calvin cycle by forming a supra-molecular complex with at least two enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase (PRK). CP12 shares some similarities with intrinsically disordered proteins (IDPs) depending on its redox state. In this study, site-directed spin labeling (SDSL) combined with EPR spectroscopy was used to probe the dynamic behavior of CP12 from Chlamydomonas reinhardtii upon binding to GAPDH, the first step towards ternary complex formation. The two N-terminal cysteine residues were labeled using the classical approach while the tyrosine located at the C-terminal end of CP12 was modified following an original procedure. The results show that the label grafted at the C-terminal extremity is in the vicinity of the interaction site whereas the N-terminal region remains fully disordered upon binding to GAPDH. In conclusion, GAPDH-CP12 is a fuzzy complex, in which the N-terminal region of CP12 keeps a conformational freedom in the bound form. This fuzziness could be one of the keys to facilitate binding of PRK to CP12-GAPDH and to form the ternary supra-molecular complex.
Aix-Marseille Université, CNRS, BIP UMR 7281, 31 chemin J. Aiguier, 13402 Marseille Cedex 20, France. belle@imm.cnrs.fr bmeunier@imm.cnrs.fr.
Elisabetta
E
Mileo
Magali
M
Lorenzi
Jenny
J
Erales
Sabrina
S
Lignon
Carine
C
Puppo
Nolwenn
N
Le Breton
Emilien
E
Etienne
Sylvain R A
SR
Marque
Bruno
B
Guigliarelli
Brigitte
B
Gontero
Valérie
V
Belle
D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D010788:Photosynthesis; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D013379:Substrate Specificity
D010940:Plant Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases