CRYSTALLIZATION OF THE MALONYL COENZYME A-ACYL CARRIER PROTEIN TRANSACYLASE FROM ESCHERICHIA-COLI

The malonyl coenzyme A-acyl carrier protein transacylase: a single pol ypeptide chain of 358 amino acid residues and a molecular mass of 32 k Da, is a key component of the fatty acid synthase multienzyme complex. The elucidation of its three-dimensional structure will help in the u nderstanding of the molecular basis of the biosynthesis of fatty acids , as well as of polyketides and related biologically active molecules. Three X-ray-duality crystal forms of the Escherichia coli fabD gene p roduct encoding for malonyl coenzyme A-acyl carrier protein transacyla se have been obtained using the hanging-drop method and ammonium sulfa te as precipitant. Two are tetragonal and each contains two molecules in the asymmetric unit (form I: space group P4(3(1))2(1)2 with a = b = 83.9 Angstrom, c = 166.5 Angstrom and form II: space group P4 with a = b = 132.64 Angstrom, c = 38.85 Angstrom), whereas the third form bel ongs to the hexagonal system and contains one molecule in the asymmetr ic unit (space group P6(1(5)) with a = b = 68.52 Angstrom, c = 117.71 Angstrom). In each case, the diffraction pattern extends to approximat ely 2.0 Angstrom resolution using CuKu radiation from a rotating anode source.