Overproduction, purification and preliminary X-ray diffraction analysis of CzcE from Cupriavidus metallidurans CH34.

CzcE is encoded by the czc determinant that allows Cupriavidus metallidurans CH34 to modulate its internal concentrations of cobalt, zinc and cadmium. This periplasmic protein was overproduced in its mature form in Escherichia coli and purified in two steps. After preliminary screening of crystallization conditions using a robot, well diffracting crystals were obtained using the hanging-drop vapour-diffusion method. Crystals diffracted to 1.96 A using synchrotron radiation. They belonged to the monoclinic space group C2, with unit-cell parameters a = 105.54, b = 29.68, c = 71.10 A. The asymmetric unit is expected to contain a dimer, in agreement with the quaternary structure deduced from gel-filtration experiments.