Crystallization and preliminary X-ray diffraction analysis of Bacillus subtilis YwfE, an L-amino-acid ligase.

Bacillus subtilis YwfE, an L-amino-acid ligase, catalyzes the formation of an α-dipeptide from L-amino acids in an ATP-dependent manner. In order to elucidate the substrate-recognition mode and the reaction mechanism of this ligase, native and selenomethionine-derivatized (SeMet) crystals of YwfE in the presence of ADP, MgCl(2) and the dipeptide L-Ala-L-Gln were obtained using the hanging-drop vapour-diffusion method. These crystals diffracted to 1.9 and 2.8 Å resolution, respectively. Preliminary SAD phase calculations using the data set from the SeMet crystal suggested that the crystal belonged to the hexagonal space group P6(5)22, with unit-cell parameters a = b = 90.85, c = 250.31 Å, and contained one molecule in the asymmetric unit with a solvent content of 57.3%.