Purification, crystallization and preliminary X-ray crystallographic analysis of the receiver and stalk domains (PA3346RS) of the response regulator PA3346 from Pseudomonas aeruginosa PAO1

The regulatory domain (PA3346RS), comprising the receiver and stalk domains, of the response regulator PA3346 requires phosphorylation for activation with magnesium ions as cofactors in order to modulate the downstream protein phosphatase activity for the regulation of swarming motility in Pseudomonas aeruginosa PAO1. Fusion-tagged recombinant PA3346RS of total molecular mass 25.3 kDa has been overexpressed in Escherichia coli, purified using Ni²⁺-NTA and Q-­Sepharose ion-exchange columns and crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from PA3346RS crystals to 2.0 Å resolution. The crystal belonged to space group P4₁ or P4₃, with unit-cell parameters a = 82.38, c = 73.34 Å. Preliminary analysis indicated the presence of a dimer of PA3346RS in the asymmetric unit, with a solvent content of 48.6%.