Crystallization and preliminary X-ray analysis of the 12S central subunit of transcarboxylase from Propionibacterium shermanii

The hexameric 12S central subunit of transcarboxylase has been crystallized in both free and substrate-bound forms. The apo crystals belong to the cub ic space group P4(2)32, with unit-cell parameters a = b = c = 188.5 Angstro m, and diffract to 3.5 Angstrom resolution. Crystals of two substrate-bound complexes, 12S with methylmalonyl CoA and 12S with malonyl CoA, are isomor phous and belong to space group C2, with unit-cell parameters a = 115.5, b = 201.4, c = 146.9 Angstrom, beta = 102.7 degrees. These crystals diffract to 1.9 Angstrom resolution with synchrotron radiation. Two useful heavy-ato m phasing derivatives of methylmalonyl CoA-bound crystals have been obtaine d by co-crystallization or crystal soaking.