Crystallization and preliminary X-ray diffraction characterization of RpfF, a key DSF synthase from Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia has emerged as a critical nosocomial opportunistic pathogen in the last few years. It is resistant to many clinically useful antibiotics; hence, new ways of combatting this bacterium are essential. Diffusible signal factor (DSF) dependent quorum sensing is a major mechanism of virulence induction in S. maltophilia, with RpfF playing a key role in DSF biosynthesis. Inhibiting S. maltophilia RpfF (SmRpfF) function via small-molecule interference may constitute a new way of treating S. maltophilia infection. SmRpfF was therefore overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals belonged to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 148.51, c = 122.82 A, and diffracted to a resolution of 2.25 A.