Purification and crystallization of Vibrio fischeri CcdB and its complexes with fragments of gyrase and CcdA.

The ccd toxin-antitoxin module from the Escherichia coli F plasmid has a homologue on the Vibrio fischeri integron. The homologue of the toxin (CcdB(Vfi)) was crystallized in two different crystal forms. The first form belongs to space group I23 or I2(1)3, with unit-cell parameter a = 84.5 A, and diffracts to 1.5 A resolution. The second crystal form belongs to space group C2, with unit-cell parameters a = 58.5, b = 43.6, c = 37.5 A, beta = 110.0 degrees, and diffracts to 1.7 A resolution. The complex of CcdB(Vfi) with the GyrA14(Vfi) fragment of V. fischeri gyrase crystallizes in space group P2(1)2(1)2(1), with unit-cell parameters a = 53.5, b = 94.6, c = 58.1 A, and diffracts to 2.2 A resolution. The corresponding mixed complex with E. coli GyrA14(Ec) crystallizes in space group C2, with unit-cell parameters a = 130.1, b = 90.8, c = 58.1 A, beta = 102.6 degrees, and diffracts to 1.95 A. Finally, a complex between CcdB(Vfi) and part of the F-plasmid antitoxin CcdA(F) crystallizes in space group P2(1)2(1)2(1), with unit-cell parameters a = 46.9, b = 62.6, c = 82.0 A, and diffracts to 1.9 A resolution.