title: Conformational selection and folding-upon-binding of intrinsically disordered protein CP12 regulate photosynthetic enzymes assembly.
abstract: Carbon assimilation in plants is regulated by the reduction of specific protein disulfides by light and their re-oxidation in the dark. The redox switch CP12 is an intrinsically disordered protein that can form two disulfide bridges. In the dark oxidized CP12 forms an inactive supramolecular complex with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase, two enzymes of the carbon assimilation cycle. Here we show that binding of CP12 to GAPDH, the first step of ternary complex formation, follows an integrated mechanism that combines conformational selection with induced folding steps. Initially, a CP12 conformation characterized by a circular structural motif including the C-terminal disulfide is selected by GAPDH. Subsequently, the induced folding of the flexible C-terminal tail of CP12 in the active site of GAPDH stabilizes the binary complex. Formation of several hydrogen bonds compensates the entropic cost of CP12 fixation and terminates the interaction mechanism that contributes to carbon assimilation control.
authors.affiliation: Department of Chemistry G Ciamician, University of Bologna, 40126 Bologna, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Fermani
authors.forename: Xavier
authors.initials: X
authors.lastname: Trivelli
authors.forename: Francesca
authors.initials: F
authors.lastname: Sparla
authors.forename: Anton
authors.initials: A
authors.lastname: Thumiger
authors.forename: Matteo
authors.initials: M
authors.lastname: Calvaresi
authors.forename: Lucia
authors.initials: L
authors.lastname: Marri
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Falini
authors.forename: Francesco
authors.initials: F
authors.lastname: Zerbetto
authors.forename: Paolo
authors.initials: P
authors.lastname: Trost
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism; D004795:Enzyme Stability / Q000502:physiology; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating) / Q000235:genetics / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D017510:Protein Folding
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D004220:Disulfides; D009097:Multienzyme Complexes; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating); D017853:Phosphotransferases (Alcohol Group Acceptor); C022390:phosphoribulokinase