Crystal structure of an iron superoxide dismutase from the pathogenic amoebaAcanthamoeba castellanii
The iron superoxide dismutase found in the pathogenic amoebaAcanthamoeba castellanii(AcFeSOD) may play essential roles in the survival of the parasite, not only by protecting it from endogenous oxidative stress but also by detoxifying oxidative killing of the parasite by host immune effector cells. TheAcFeSOD protein was expressed in a stable form using anEscherichia coliexpression system and was crystallized by the microbatch and hanging-drop vapour-diffusion methods. The structure was determined to 2.33 Å resolution from a singleAcFeSOD crystal. The crystal belonged to the hexagonal space groupP61and contained 12 molecules forming three tetramers in the asymmetric unit, with an iron ion bound in each molecule. Structural comparisons and sequence alignment ofAcFeSOD with other FeSODs showed a well conserved overall fold and conserved active-site residues with subtle differences.