Crystallization and preliminary X-ray crystallographic analysis of S-allelic glycoprotein S_F11-RNase from Nicotiana alata

Nicotiana alata S_F11-RNase is an S-glycoprotein associated with gametophytic self-incompatibility. Crystals of S_F11-RNase have been grown at room temperature using polyethylene glycol as a precipitant. A crystal diffracted to better than 1.4 Å resolution at 100 K at the SPring-8 synchrotron-radiation source, indicating that it is very suitable for high-resolution structure analysis. The crystal belongs to the space group P2₁, with unit-cell parameters a = 65.86 (11), b = 44.73 (5), c = 64.36 (7) Å, β = 90.27 (9)°. The asymmetric unit contains two monomers, giving a crystal volume per protein mass (V_M) of 2.05 ų Da⁻¹ and a solvent content of 39.6% by volume. A full set of X-ray diffraction data was collected to 1.55 Å resolution with a completeness of 97.4%. A heavy-atom derivative has been successfully prepared with ethylmercury thiosalicylate (EMTS) and structure analysis is in progress.