Preliminary X-ray crystallographic analysis of a novel phytase from a Bacillus amyloliquefaciens strain

A novel bacterial phytase from a Bacillus amyloliquefaciens strain was crystallized using the hanging-drop vapour-diffusion method. The amino-acid sequence of the enzyme does not show any homology to those of other known phytases or phosphatases, with the exception of a phytase from Bacillus subtilis. The enzyme exhibits a thermal stability which is strongly dependent on calcium ions. High-quality single crystals of the enzyme in the absence of calcium ions were obtained using a precipitant solution containing 20% 2-methyl-2,4-pentanediol and 0.1 M MES (pH 6.5). Native diffraction data to 2.0 Å resolution were obtained from a flash-frozen crystal at 110 K using a rotating-anode X-ray source. The crystals belong to space group P2₁2₁2₁ with unit-cell dimensions a = 50.4, b = 64.1, c = 104.2 Å and contain one monomer per asymmetric unit. Structure determination using heavy-atom derivative crystals is in progress, along with an effort to crystallize the calcium ion bound form of the enzyme.