GPX3 from Arabidopsis thaliana: cloning, expression, purification, crystallization and preliminary X-ray analysis

The Arabidopsis thaliana glutathione peroxidase 3 (GPX3) gene encodes a glutathione peroxidase with roles in H₂O₂ homeostasis and signalling. The GPX3 gene sequence was cloned into pGEX-6P1 and overexpressed in Escherichia coli. The GPX3 protein was purified to homogeneity in two chromatographic steps. Various lengths of the GPX3 sequence were used to obtain proteins that yielded crystals using vapour-diffusion techniques, but only GPX3ΔN36 (lacking 36 amino acids from the N-terminus) showed a good diffraction pattern. Its crystals diffracted to 2.8 Å resolution and belonged to space group P6₅, with unit-cell parameters a = b = 98.241, c = 42.057 Å.