Crystallization of the C-terminal redox domain of the sulfur-assimilatory enzyme APR1 from Arabidopsis thaliana.

Plant-type APS reductase (APR), which catalyzes the reduction of activated sulfate to sulfite in plants, consists of a reductase domain and a C-terminal redox domain showing sequence homology to thioredoxin but possessing the activity of glutaredoxin. In order to understand the structural and biochemical properties of the redox domain of plant-type APS reductase, the C-terminal domain of APR1 (APR1C) from Arabidopsis thaliana was crystallized using the sitting-drop vapour-diffusion method. X-ray diffraction data were collected to a resolution of 2.70 Å on the SPXF beamline BL13B1 at the NSRRC, Taiwan. The crystals belonged to space group P43212 or P41212, with unit-cell parameters a = b = 58.2, c = 86.7 Å. With one molecule per asymmetric unit, the crystal volume per unit protein weight (VM) is 2.64 Å(3) Da(-1), which corresponds to a solvent content of approximately 53.49%. Further structure-based functional studies of APR1C would extend knowledge of the molecular mechanism and regulation of APR.