Crystallization and preliminary crystallographic analysis of an Enterococcus faecalis repressor protein, CylR2,...

CylR2 is one of two regulatory proteins associated with the quorum-sensing-dependent synthesis of cytolysin in the common pathogen Enterococcus faecalis. The protein was expressed with a C-terminal six-histidine tag and purified to homogeneity with a cobalt-affinity column followed by size-exclusion chromatography. Both native and SeMet proteins were produced and crystallized. Complete X-ray diffraction data sets were collected from a native crystal, which diffracted to 2.3 angstroms resolution, and a SeMet crystal, which diffracted to 2.1 angstroms. The crystals were tetragonal, belonging to space group P4(1) or P4(3), with unit-cell parameters a = b = 66.2, c = 40.9 angstroms, alpha = beta = gamma = 90 degrees. Based on the calculated Matthews coefficient of 2.6 angstroms3 Da(-1) as well as analysis of anomalous difference Patterson maps, the asymmetric unit most likely contains two molecules of CylR2.