Crystallization and preliminary X-ray analysis of native and selenomethionine fructose-1,6-bisphosphate aldolase from Thermus aquaticus

Fructose-1,6-bisphosphate aldolase (E.C. 4.1.2) catalyses the reversible cl eavage of fructose-1,6-bisphosphate to dihydroxyacetone phosphate and glyce raldehyde-3-phosphate in the glycolytic pathway of prokaryote and eukaryote organisms. The enzyme was obtained from the extreme thermophile Thermus aq uaticus and, in contrast to mesophilic aldolases, expresses maximal activit y in the presence of Co2+ as cofactor instead of Zn2+. The purified recombi nant protein was monodisperse according to dynamic light-scattering measure ments. Crystals of recombinant native class II fructose-1,6-bisphosphate al dolase from T. aquaticus were obtained from two different starting conditio ns at low protein concentrations. Condition I, using the sitting-drop vapou r-diffusion method, yielded monoclinic crystals having space group P2 and u nit-cell parameters a = 99.5, b = 57.5, c = 138.6 Angstrom, beta = 90.25 de grees. Diffraction data were collected to 2 Angstrom resolution at beamline X8-C of the NSLS synchrotron-radiation source. Native and selenomethionine -substituted protein crystals were obtained from condition II by hanging-dr op vapor diffusion. The tetragonal crystals of the native protein belong to the space group P4(1), with unit-cell parameters a = b = 88.8, c = 163.1 A ngstrom, while those of the SeMet protein have space group I4(1), with unit -cell parameters a = b = 88.6, c = 164.1 Angstrom. A data set suitable for MAD phasing was collected to 2.6 Angstrom resolution at beamline X8-C of th e NSLS synchrotron source.