Crystallization and preliminary X-ray analysis of Acetivibrio cellulolyticus cellulosomal type II cohesin module: Two versions having different linker lengths

The second type II cohesin module of the cellulosomal scaffoldin polypeptide ScaB from Acetivibrio cellulolyticus (CohB2) was cloned into two constructs: one containing a short (five-residue) C-terminal linker (CohB2_S) and the second incorporating the full native 45-residue linker (CohB2_L). Both constructs encode proteins that also include the full native six-residue N-terminal linker. The CohB2_S and CohB2_L proteins were expressed, purified and crystallized in the orthorhombic crystal system, but with different unit cells and symmetries: space group P2₁2₁2₁ with unit-cell parameters a = 90.36, b = 68.65, c = 111.29 Å for CohB2_S and space group P2₁2₁2 with unit-cell parameters a = 68.76, b = 159.22, c = 44.21 Å for CohB2_L. The crystals diffracted to 2.0 and 2.9 Å resolution, respectively. The asymmetric unit of CohB2_S contains three cohesin molecules, while that of CohB2_L contains two molecules.