Cloning, overexpression, purification, crystallization, and preliminary X-ray studies of SP_0149, the substrate binding protein of an ABC transporter from Streptococcus pneumoniae.

A truncated (29 residues from the N-terminus) and N-terminal His-tagged form of SP_0149 from pneumococcal strain ATCC BAA-334 was overexpressed and purified to homogeneity using affinity and gel-filtration chromatography. Diffraction quality crystals were grown at 293 K using the hanging-drop vapour-diffusion technique. X-ray diffraction data were collected to 2.3 Å resolution from a single-crystal that belonged to the orthorhombic space group P2(1)2(1)2(1) with the unit-cell parameters a=54.56, b=75.61, c=75.52 Å. The calculated values of the Matthews coefficient assuming one molecule (with calculated molecular weight of 30 400 Da) in the crystal asymmetric unit and the corresponding solvent content were 2.56 Å3 Da(-1) and 52.0%, respectively.