Expression, purification and crystallization of a fungal type III polyketide synthase that produces the csypyrones

CsyB from Aspergillus oryzae is a novel type III polyketide synthase that catalyzes the formation of csypyrone B1 [4-(3-acetyl-4-hydroxy-2-oxo-2H-pyran-6-yl)butyric acid] from fatty acyl-CoA, malonyl-CoA and acetoacetyl-CoA. Recombinant CsyB expressed in Escherichia coli was crystallized by the sitting-drop vapour-diffusion method. The crystals belonged to space P2₁, with unit-cell parameters a = 70.0, b = 104.8, c = 73.5 Å, β = 114.4°.