Crystallization and preliminary X-ray analysis of bacteriophage T4 UvsY recombination mediator protein

Bacteriophage T4 UvsY protein is considered to be the prototype of recombination mediator proteins, a class of proteins which assist in the loading of recombinases onto DNA. Wild-type and Se-substituted UvsY protein have been expressed and purified and crystallized by hanging-drop vapor diffusion. The crystals diffract to 2.4 A using in-house facilities and to 2.2 A at NSLS, Brookhaven National Laboratory. The crystals belong to space group P422, P4(2)22, P42(1)2 or P4(2)2(1)2, the ambiguity arising from pseudo-centering, with unit-cell parameters a = b = 76.93, c = 269.8 A. Previous biophysical characterization of UvsY indicates that it exists primarily as a hexamer in solution. Along with the absence of a crystallographic threefold, this suggests that the asymmetric unit of these crystals is likely to contain either three monomers, giving a solvent content of 71%, or six monomers, giving a solvent content of 41%.