Striking conformational change suspected within the phosphoribulokinase dimer induced by interaction with GAPDH.
A multitechnique approach was used to study the [glyceraldehyde-3-phosphate dehydrogenase](2 x 4)-[phosphoribulokinase](2 x 2) multienzymatic complex of the alga Chlamydomonas reinhardtii. On the one hand, each component of the complex was compared with known atomic structures of related enzymes or of similar enzymes originating from different organisms. On the other hand, the overall low resolution architecture of the whole complex was studied using cryoelectron microscopy and image processing techniques. The dimers of phosphoribulokinase are suspected to undergo a dramatic change in activity during a cycle of binding and detaching from tetramers of glyceraldehyde-3-phosphate dehydrogenase. This is likely supported by strong structural differences between the modeled phosphoribulokinase dimers and the counterpart in the three-dimensional reconstruction volume of the whole complex obtained from cryoelectron microscope images.
Mouche
Fabrice
F
Laboratoire de Minéralogie Cristallographie Paris, CNRS, UMR-7590, Universités Paris 6 et Paris 7, Case 115, 4 Place Jussieu, 75252 Paris Cedex 05, France.
Gontero
Brigitte
B
Callebaut
Isabelle
I
Mornon
Jean-Paul
JP
Boisset
Nicolas
N
D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii; D020285:Cryoelectron Microscopy; D019281:Dimerization; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure*; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D011487:Protein Conformation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D046911:Macromolecular Substances; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D017853:Phosphotransferases (Alcohol Group Acceptor); C022390:phosphoribulokinase