CRYSTALLIZATION AND PRELIMINARY-X-RAY STUDY OF THE 8-AMINO-7-OXOPELARGONATE SYNTHASE FROM BACILLUS-SPHAERICUS

The 8-amino-7-oxopelargonate synthase (AOPS) cloned from Bacillus spha ericus, overproduced in Escherichia coli, has been crystallized in the pyridoxal 5'-phosphate (PLP)-bound form at pH 7.5, using polyethylene glycol as the precipitant. One crystal form corresponds to a tetragon al space group, with unit-cell dimensions a = b = 66, c = 181 Angstrom . These crystals do not diffract beyond 5 Angstrom with conventional X -ray sources and cannot be used in the structure elucidation. A second crystal form is obtained when crystallization conditions are varied s lightly by the addition of 0.2M ammonium sulfate. The space group is P 2(1)2(1)2(1), with unit-cell dimensions a = 68.9, b = 85.5, c = 125.9 A, indicating the presence of two molecules in the asymmetric unit (V- m = 2.26 Angstrom(3) Da(-1); 46% water). These crystals diffract X-ray s up to 3.2 Angstrom using in-house facilities and a preliminary data set has been collected. A second data set using the synchrotron radiat ion source W32 at LURE (Paris) has shown the crystals to diffract to a t least 3 Angstrom resolution, with good statistics. The structure det ermination of AOPS will provide a structural framework for the other a lpha-amino ketone synthases for which no three-dimensional structure i s yet available.