CRYSTALLIZATION OF INHIBITOR COMPLEXES OF AN N-TERMINAL 24-KDA FRAGMENT OF THE DNA GYRASE-B PROTEIN

A 24 kDa N-terminal fragment of the Escherichia coli DNA gyrase B prot ein has been crystallized in the presence of novobiocin. One crystal f orm has been obtained that is orthorhombic, P2(1)2(1)2(1), with unit c ell dimensions a=403 Angstrom, b=47.7 Angstrom, c=111.9 Angstrom. The asymmetric unit of this crystal form contains one molecule (V-m=2.24 A ngstrom(3)/Da). Complete native data have been collected to 2.5 Angstr om resolution. This same protein fragment has also been crystallized i n the presence of GR122222X, an inhibitor that is structurally related to cyclothialidine. These crystals also exhibit P2(1)2(1)2(1), symmet ry but have unit cell dimensions of a=68.8 Angstrom, b=68.6 Angstrom, c=48.6 Angstrom. The V-m value of this crystal form is 2.39 Angstrom(3 )/Da, assuming one molecule in the asymmetric unit, and native data ha ve been collected to 2.0 Angstrom resolution. Molecular replacement st udies of both complexes are underway.