A Periplasmic Glutamate/Aspartate Binding Protein from Shigella flexneri: Gene Cloning, Over-Expression, Purification and Preliminary Crystallographic Studies of the Recombinant Protein

Periplasmic substrate binding proteins (PSBPs) are essential components of the bacterial periplasmic transport system, which transports a wide variety of nutrients from the periplasmic space to the cytoplasm. The glutamate/aspartate binding protein SfGlu/AspBP is a unique PSBP consisting of 279 amino acid residues. The SfGlu/AspBP gene was cloned, over-expressed, and purified by immobilized metal ion affinity chromatography and size-exclusion chromatography. The recombinant protein SfGlu/AspBP has been crystallized by the hanging-drop vapor-diffusion method and its Xray diffraction data were collected at an atomic resolution of 1.15 Å. The crystals belong to the space group P21 with unit cell parameters: a=48.41 Å, b=68.18 Å, c=80.21 Å and b = 98.78 . There are two molecules per asymmetric unit.