Purification, crystallization and preliminary X-ray diffraction analysis of the yeast phosphorelay protein YPD1.

YPD1 is a yeast osmoregulatory protein that functions in a phosphorelay signal-transduction pathway. YPD1 has been expressed in Escherichia coli, purified to homogeneity and crystallized. The crystals were obtained by hanging-drop vapor-diffusion using PEG 4000 as a precipitant. Preliminary X-ray diffraction analysis indicates that the crystals belong to tetragonal space group P43212 or P41212 with unit-cell dimensions a = b = 52.71, c = 244.02 A. X-ray data to 2.7 and 3.0 A have been collected from native crystals and a heavy-atom derivative, respectively. Positions for two Hg atoms have been located by analysis of difference Patterson maps.