Overproduction, purification, crystallization and preliminary X-ray diffraction analysis of YopM, an essential virulence factor extruded by the plague bacterium Yersinia pestis

A recombinant form of Yersinia pestis YopM with a C-terminal polyhistidine affinity tag has been overproduced in Escherichia coli, purified to homogeneity and crystallized using the hanging-drop vapor-diffusion technique. Several different crystal forms were obtained. The most suitable crystals for X-ray diffraction belonged to space groups P4₂22 (unit-cell parameters a = 109.36, b = 109.36, c = 101.50 Å) and C222₁ (unit-cell parameters a = 71.73, b = 121.85, c = 189.79 Å). With a synchrotron-radiation source, these crystals diffracted to 2.4 and 1.9 Å resolution, respectively.