Crystallization and preliminary X-ray diffraction analysis of the cytosolic domain of the Mg2+ transporter MgtE.

The MgtE family of Mg(2+) transporters is ubiquitously conserved in all domains of life. The cytosolic domains of the MgtE Mg(2+) transporters include a cystathionine-beta-synthase (CBS) domain which is known to play a regulatory function in transporter proteins. The cytosolic domain of MgtE from Thermus thermophilus was overexpressed, purified and crystallized in the presence and absence of Mg(2+). The crystals formed in the presence of Mg(2+) diffracted X-rays to 2.3 A resolution using synchrotron radiation, belong to space group P6(5)22 with unit-cell parameters a = b = 57.7, c = 317.6 A and are expected to contain one molecule in the asymmetric unit. The crystals formed in the absence of Mg(2+) diffracted X-rays to 3.5 A resolution using synchrotron radiation, belong to space group P2(1)2(1)2(1) with unit-cell parameters a = 77.0, b = 100.3, c = 100.3 A and are expected to contain two molecules in the asymmetric unit.