Expression, purification and preliminary X-ray crystallographic analysis of PsaA, a putative metal-transporter protein of Streptococcus pneumoniae

The putative metal-transporter protein PsaA of Streptococcus pneumoniae is of potential interest both as a vaccine and also as a drug target. The overexpression of the protein in E. coli, and its subsequent purification and crystallization are described. The crystals are rectangular rods and diffract to beyond 2.7 Å resolution. The crystal space group is P2₁2₁2₁ with unit-cell dimensions a = 59.9, b = 66.5 and c = 69.9 Å.