Crystal structures of human calcineurin and the human FKBP12-FK506-calcineurin complex.
Calcineurin (CaN) is a calcium- and calmodulin-dependent protein serine/threonine phosphate which is critical for several important cellular processes, including T-cell activation. CaN is the target of the immunosuppressive drugs cyclosporin A and FK506, which inhibit CaN after forming complexes with cytoplasmic binding proteins (cyclophilin and FKBP12, respectively). We report here the crystal structures of full-length human CaN at 2.1 A resolution and of the complex of human CaN with FKBP12-FK506 at 3.5 A resolution. In the native CaN structure, an auto-inhibitory element binds at the Zn/Fe-containing active site. The metal-site geometry and active-site water structure suggest a catalytic mechanism involving nucleophilic attack on the substrate phosphate by a metal-activated water molecule. In the FKBP12-FK506-CaN complex, the auto-inhibitory element is displaced from the active site. The site of binding of FKBP12-FK506 appears to be shared by other non-competitive inhibitors of calcineurin, including a natural anchoring protein.
Agouron Pharmaceuticals Inc., San Diego, California 92121-1121, USA.
C R
CR
Kissinger
H E
HE
Parge
D R
DR
Knighton
C T
CT
Lewis
L A
LA
Pelletier
A
A
Tempczyk
V J
VJ
Kalish
K D
KD
Tucker
R E
RE
Showalter
E W
EW
Moomaw
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001665:Binding Sites; D019703:Calcineurin; D002118:Calcium / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry; D016559:Tacrolimus / Q000737:chemistry / Q000378:metabolism*; D022021:Tacrolimus Binding Proteins; D014867:Water / Q000378:metabolism
D054758:A Kinase Anchor Proteins; C487775:AKAP5 protein, human; D048868:Adaptor Proteins, Signal Transducing; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D006360:Heat-Shock Proteins; D011506:Proteins; D011994:Recombinant Proteins; D014867:Water; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D022021:Tacrolimus Binding Proteins; D002118:Calcium; D016559:Tacrolimus