Expression, refolding, crystallization and preliminary X-ray analysis of Pseudomonas aeruginosa AlgE

AlgE is an outer membrane protein present in alginate-producing (mucoid) Pseudomonas aeruginosa. AlgE has been overexpressed in insoluble inclusion bodies, purified under denaturing conditions and refolded in a buffer containing decyl β-D-maltopyranoside. Purified refolded AlgE was detergent-exchanged into n-octyl tetraoxyethylene and diffraction-quality crystals were grown using the hanging-drop vapor-diffusion method. The crystals grew as small hexagons with unit-cell parameters a = 98.8, b = 156.8, c = 90.4 Å, α = β = γ = 90.0°. The crystals exhibited the symmetry of space group C222 and diffracted to a minimum d-­spacing of 3.0 Å. On the basis of the Matthews coefficient (V_M = 3.28 ų Da⁻¹), one molecule is estimated to be present in the asymmetric unit.