Overexpression, purification, crystallization and preliminary structural studies of p-coumaric acid decarboxylase from Lactobacillus plantarum.

The substrate-inducible p-coumaric acid decarboxylase (PDC) from Lactobacillus plantarum has been overexpressed in Escherichia coli, purified and confirmed to possess decarboxylase activity. The recombinant His(6)-tagged enzyme was crystallized using the hanging-drop vapour-diffusion method from a solution containing 20%(w/v) PEG 4000, 12%(w/v) 2-propanol, 0.2 M sodium acetate, 0.1 M Tris-HCl pH 8.0 with 0.1 M barium chloride as an additive. Diffraction data were collected in-house to 2.04 A resolution. Crystals belonged to the tetragonal space group P4(3), with unit-cell parameters a = b = 43.15, c = 231.86 A. The estimated Matthews coefficient was 2.36 A(3) Da(-1), corresponding to 48% solvent content, which is consistent with the presence of two protein molecules in the asymmetric unit. The structure of PDC has been determined by the molecular-replacement method. Currently, the structure of PDC complexed with substrate analogues is in progress, with the aim of elucidating the structural basis of the catalytic mechanism.