Structural studies of the Hrp secretion system: expression, purification, crystallization and preliminary X-ray analysis of the C-terminal domain of the HrcQ(B) protein from Pseudomonas syringae pv. phaseolicola

The C-terminal domain of the HrcQ(B) protein from the Hrp secretion system of the plant pathogenic bacterium Pseudomonas syringae pv. phaseolicola has been crystallized from MPD using the hanging-drop vapour-diffusion method. The crystals belong to space group P2(1), with unit-cell parameters a = 51 .6, b = 27.3, c = 97.2 Angstrom and beta = 99.8 degrees. A complete native data set extending to 3.0 Angstrom resolution was collected from a single c ryoprotected crystal. The crystal solvent content and calculation of self-r otation functions showing non-crystallographic twofold symmetry axes are co nsistent with the presence of an oligomeric assembly in the asymmetric unit .