Crystallization and preliminary X-ray diffraction analysis of the chloramphenicol acetyltransferase from Tn2424

Crystals of chloramphenicol acetyltransferase B2, an enzyme encoded by the transposon Tn2424 from Escherichia coli, have been obtained utilizing polye thylene glycol as a precipitant. The enzyme inactivates the antibiotic chlo ramphenicol and is a member of the xenobiotic acetyltransferase family. Two crystal forms were obtained and complete data sets have been collected at a synchrotron source: form I, which diffracted to 3.2 Angstrom, and form II , grown in the presence of NiCl2, for which crystals of the apoenzyme and o f the enzyme-chloramphenicol complex have been obtained. For the form II cr ystals, complete data sets have been collected at 2.7 and 3.2 Angstrom reso lution, respectively. The space group of the above two crystal forms is P2( 1)3, with unit-cell parameter a = 130 Angstrom.