Overproduction, crystallization and preliminary X-­ray characterization of Abn2, an endo-1,5-α-arabinanase from Bacillus subtilis

Two Bacillus subtilis extracellular endo-1,5-α-L-arabinanases, AbnA and Abn2, belonging to glycoside hydrolase family 43 have been identified. The recently characterized Abn2 protein hydrolyzes arabinan and has low identity to other reported 1,5-α-L-arabinanases. Abn2 and its selenomethionine (SeMet) derivative have been purified and crystallized. Crystals appeared in two different space groups: P1, with unit-cell parameters a = 51.9, b = 57.6, c = 86.2 Å, α = 82.3, β = 87.9, γ = 63.6°, and P2₁2₁2₁, with unit-cell parameters a = 57.9, b = 163.3, c = 202.0 Å. X-ray data have been collected for the native and the SeMet derivative to 1.9 and 2.7 Å resolution, respectively. An initial model of Abn2 is being built in the SeMet-phased map.