Recombinant production, crystallization and X-ray crystallographic structure determination of the peptidyl-tRNA hydrolase of Pseudomonas aeruginosa.

The peptidyl-tRNA hydrolase enzyme from the pathogenic bacterium Pseudomonas aeruginosa (Pth; EC 3.1.1.29) has been cloned, expressed in Escherichia coli and crystallized for X-ray structural analysis. Suitable crystals were grown using the sitting-drop vapour-diffusion method after one week of incubation against a reservoir solution consisting of 20% polyethylene glycol 4000, 100 mM Tris pH 7.5, 10%(v/v) isopropyl alcohol. The crystals were used to obtain the three-dimensional structure of the native protein at 1.77 Å resolution. The structure was determined by molecular replacement of the crystallographic data processed in space group P6(1)22 with unit-cell parameters a=b=63.62, c=155.20 Å, α=β=90, γ=120°. The asymmetric unit of the crystallographic lattice was composed of a single copy of the enzyme molecule with a 43% solvent fraction, corresponding to a Matthews coefficient of 2.43 Å3 Da(-1). The crystallographic structure reported here will serve as the foundation for future structure-guided efforts towards the development of novel small-molecule inhibitors specific to bacterial Pths.