Crystallization and X-ray analysis of native and selenomethionyl β-mannanase Man5A from blue mussel, Mytilus edulis, expressed in Pichia pastoris

The glycohydrolase family 5 beta-mannanase Man5A from Mytilus edulis has been expressed in Pichia pastoris and purified in a form suitable for X-ray crystallographic analysis. Crystals were grown by the hanging-drop technique at 293 K using polyethylene glycol 5000 monomethylether as precipitant and dioxane as additive. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 61.8, b = 64.8, c = 90.7 Angstrom. Diffraction to 1.4 Angstrom resolution has been obtained at 100 K. Expression was also performed in the presence of selenomethionine. The incorporation of SeMet was estimated at 40% by amino-acid analysis and its presence in crystals was confirmed from the X-ray absorption scanning spectrum.