Structure of the manganese superoxide dismutase from Deinococcus radiodurans in two crystal forms

The structure of the manganese superoxide dismutase (Mn-SOD; DR1279) from Deinococcus radiodurans has been determined in two different crystal forms. Both crystal forms are monoclinic with space group P2₁. Form I has unit-cell parameters a = 44.28, b = 83.21, c = 59.52 Å, β = 110.18° and contains a homodimer in the asymmetric unit, with structure refinement (R = 16.8%, R_free = 23.6%) carried out using data to d_min = 2.2 Å. Form II has unit-cell parameters a = 43.57, b = 87.10, c = 116.42 Å, β = 92.1° and an asymmetric unit containing two Mn-SOD homodimers; structure refinement was effected to a resolution of 2.0 Å (R = 17.2%, R_free = 22.3%). The resulting structures are compared with that of Mn-SOD from Escherichia coli, with which they are shown to be essentially isostructural.