Characterization of Arabidopsis thaliana AtFKBP42 that is membrane‐bound and interacts with Hsp90

• Published in: The Plant journal : for cell and molecular biology 2002-11, Vol.32 (3), p.263-276
• Main Authors: Kamphausen, Thilo, Fanghänel, Jörg, Neumann, Dieter, Schulz, Burkhard, Rahfeld, Jens‐U.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - ultrastructure; Arabidopsis Proteins - genetics; Arabidopsis Proteins - isolation & purification; Arabidopsis Proteins - metabolism; Biological and medical sciences; Calmodulin-Binding Proteins - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Circular Dichroism; Citrate (si)-Synthase - metabolism; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes. Genome; Hsp90; HSP90 Heat-Shock Proteins - metabolism; Membrane Proteins - genetics; Membrane Proteins - metabolism; Microscopy, Electron; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutation; Peptidylprolyl Isomerase - metabolism; plasma membrane; PPIase; Protein Binding; Protein Conformation; Protein Interaction Mapping; Sequence Homology, Amino Acid; signal transduction; Spectrum Analysis - methods; steroid hormone receptor; Tacrolimus Binding Proteins - genetics; Tacrolimus Binding Proteins - isolation & purification; Tacrolimus Binding Proteins - metabolism
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2002.01420.x

Summary 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.