Conformational selection and folding-upon-binding of intrinsically disordered protein CP12 regulate photosynthetic enzymes assembly

J Biol Chem. 2012 Jun 15;287(25):21372-83. doi: 10.1074/jbc.M112.350355. Epub 2012 Apr 18.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Disulfides / metabolism
  • Enzyme Stability / physiology
  • Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating) / genetics
  • Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating) / metabolism
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism
  • Photosynthesis / physiology*
  • Protein Folding*


  • Arabidopsis Proteins
  • Carrier Proteins
  • Disulfides
  • Multienzyme Complexes
  • Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating)
  • Phosphotransferases (Alcohol Group Acceptor)
  • phosphoribulokinase

Associated data

  • PDB/2LJ9
  • PDB/3QV1
  • PDB/3RVD