Cloning, purification, crystallization and preliminary X-ray crystallographic analysis of a cyclophilin A-like protein from Piriformospora indica

Cyclophilins are widely distributed both in eukaryotes and prokaryotes and have a primary role as peptidyl-prolyl cis-trans isomerases (PPIases). This study focuses on the cloning, expression, purification and crystallization of a salinity-stress-induced cyclophilin A (CypA) homologue from the symbiotic fungus Piriformospora indica. Crystallization experiments in the presence of 56 mM sodium phosphate monobasic monohydrate, 1.34 M potassium phosphate dibasic pH 8.2 yielded crystals that were suitable for X-ray diffraction analysis. The crystals belonged to the orthorhombic space group C222₁, with unit-cell parameters a = 121.15, b = 144.12, c = 110.63 Å. The crystals diffracted to a resolution limit of 2.0 Å. Analysis of the diffraction data indicated the presence of three molecules of the protein per asymmetric unit (V_M = 4.48 Å³ Da^-1, 72.6% solvent content).