Expression, purification, crystallization and preliminary crystallographic studies of the Enterococcus faecalis cytolysin repressor CylR2

Abstract

The expression of an exotoxin called cytolysin contributes to the virulence of Enterococcus faecalis, one of the organisms responsible for antibiotic resistant infections acquired in hospitals. The DNA-binding protein CylR2 is a transcriptional repressor of cytolysin. At a specific cell density, cytolysin triggers signaling events, which result in the dissociation of CylR2 from its DNA-binding site. CylR2 was overexpressed in Escherichia coli and purified and crystals diffracting to 1.9 A were obtained in two different crystal forms. One crystal form belongs to space group P4(1), with unit-cell parameters a = 63.7, b = 63.7, c = 41.2 A, alpha = beta = gamma = 90 degrees, and the other belongs to space group P1, with unit-cell parameters a = 36.9, b = 45.0, c = 47.7 A, alpha = 67, beta = 90, gamma = 66 degrees.