Characterization of Arabidopsis thaliana AtFKBP42 that is membrane-bound and interacts with Hsp90.
The twisted dwarf1 (twd1) mutant from Arabidopsis thaliana was identified in a screen for plant architecture mutants. The TWD1 gene encodes a 42 kDa FK506-binding protein (AtFKBP42) that possesses similarity to multidomain PPIases such as mammalian FKBP51 and FKBP52, which are known to be components of mammalian steroid hormone receptor complexes. We report here for the first time the stoichiometry and dissociation constant of a protein complex from Arabidopsis that consists of AtHsp90 and AtFKBP42. Recombinant AtFKBP42 prevents aggregation of citrate synthase in almost equimolar concentrations, and can be cross-linked to calmodulin. In comparison to one active and one inactive FKBP domain in FKBP52, AtFKBP42 lacks the PPIase active FKBP domain. While FKBP52 is found in the cytosol and translocates to the nucleus, AtFKBP42 was predicted to be membrane-localized, as shown by electron microscopy.
Kamphausen
Thilo
T
Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, Germany.
Fanghänel
Jörg
J
Neumann
Dieter
D
Schulz
Burkhard
B
Rahfeld
Jens-U
JU
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002942:Circular Dichroism; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009154:Mutation; D019696:Peptidylprolyl Isomerase / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D017386:Sequence Homology, Amino Acid; D013057:Spectrum Analysis / Q000379:methods; D022021:Tacrolimus Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D029681:Arabidopsis Proteins; D002148:Calmodulin-Binding Proteins; D018841:HSP90 Heat-Shock Proteins; D008565:Membrane Proteins; C471286:TWD1 protein, Arabidopsis; D002950:Citrate (si)-Synthase; D022021:Tacrolimus Binding Proteins; D019696:Peptidylprolyl Isomerase