Structure of the complex between the cytosolic chaperonin CCT and phosducin-like protein.
The three-dimensional structure of the complex formed between the cytosolic chaperonin CCT (chaperonin containing TCP-1) and phosducin (Pdc)-like protein (PhLP), a regulator of CCT activity, has been solved by cryoelectron microscopy. Binding of PhLP to CCT occurs through only one of the chaperonin rings, and the protein does not occupy the central folding cavity but rather sits above it through interactions with two regions on opposite sides of the ring. This causes the apical domains of the CCT subunits to close in, thus excluding access to the folding cavity. The atomic model of PhLP generated from several atomic structures of the homologous Pdc fits very well with the mass of the complex attributable to PhLP and predicts the involvement of several sequences of PhLP in CCT binding. Binding experiments performed with PhLP/Pdc chimeric proteins, taking advantage of the fact that Pdc does not interact with CCT, confirm that both the N- and C-terminal domains of PhLP are involved in CCT binding and that several regions suggested by the docking experiment are indeed critical in the interaction with the cytosolic chaperonin.
Martín-Benito
Jaime
J
Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Campus de la Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Bertrand
Sara
S
Hu
Ting
T
Ludtke
Paul J
PJ
McLaughlin
Joseph N
JN
Willardson
Barry M
BM
Carrascosa
José L
JL
Valpuesta
José M
JM
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D002417:Cattle; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D016415:Sequence Alignment
D002352:Carrier Proteins; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; C498320:Pdcl protein, rat; D021122:Protein Subunits; D056404:Chaperonin Containing TCP-1; D018833:Chaperonins