title: Structural and biochemical characterization of the cytosolic wheat cyclophilin TaCypA-1.
abstract: Cyclophilins belong to a family of proteins that bind to the immunosuppressive drug cyclosporin A (CsA). Several members of this protein family catalyze the cis-trans isomerization of peptide bonds preceding prolyl residues. The present study describes the biochemical and structural characteristics of a cytosolic cyclophilin (TaCypA-1) cloned from wheat (Triticum aestivum L.). Purified TaCypA-1 expressed in Escherichia coli showed peptidyl-prolyl cis-trans isomerase activity, which was inhibited by CsA with an inhibition constant of 78.3 nM. The specific activity and catalytic efficiency (kcat/Km) of the purified TaCypA-1 were 99.06 ± 0.13 nmol s(-1) mg(-1) and 2.32 × 10(5) M(-1) s(-1), respectively. The structures of apo TaCypA-1 and the TaCypA-1-CsA complex were determined at 1.25 and 1.20 Å resolution, respectively, using X-ray diffraction. Binding of CsA to the active site of TaCypA-1 did not result in any significant conformational change in the apo TaCypA-1 structure. This is consistent with the crystal structure of the human cyclophilin D-CsA complex reported at 0.96 Å resolution. The TaCypA-1 structure revealed the presence of a divergent loop of seven amino acids (48)KSGKPLH(54) which is a characteristic feature of plant cyclophilins. This study is the first to elucidate the structure of an enzymatically active plant cyclophilin which shows peptidyl-prolyl cis-trans isomerase activity and the presence of a divergent loop.
authors.affiliation: Medical Proteomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea.
authors.forename: Simranjeet Singh
authors.initials: SS
authors.lastname: Sekhon
authors.forename: Harsimran
authors.initials: H
authors.lastname: Kaur
authors.forename: Tanima
authors.initials: T
authors.lastname: Dutta
authors.forename: Khushwant
authors.initials: K
authors.lastname: Singh
authors.forename: Sumita
authors.initials: S
authors.lastname: Kumari
authors.forename: Sunghyun
authors.initials: S
authors.lastname: Kang
authors.forename: Sung Goo
authors.initials: SG
authors.lastname: Park
authors.forename: Byoung Chul
authors.initials: BC
authors.lastname: Park
authors.forename: Dae Gwin
authors.initials: DG
authors.lastname: Jeong
authors.forename: Ashwani
authors.initials: A
authors.lastname: Pareek
authors.forename: Eui-Jeon
authors.initials: EJ
authors.lastname: Woo
authors.forename: Prabhjeet
authors.initials: P
authors.lastname: Singh
authors.forename: Tae-Sung
authors.initials: TS
authors.lastname: Yoon
mesh_terms: D018360:Crystallography, X-Ray; D021984:Cyclophilin A / Q000737:chemistry* / Q000378:metabolism; D016572:Cyclosporine / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry; D007166:Immunosuppressive Agents / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D014908:Triticum / Q000737:chemistry*
chemical_list: D007166:Immunosuppressive Agents; D010940:Plant Proteins; D016572:Cyclosporine; D021984:Cyclophilin A
keywords: Triticum aestivum; cyclophilins; peptidyl-prolyl cis–trans isomerase