BETA-LACTAMASE TEM1 OF ESCHERICHIA-COLI - CRYSTAL-STRUCTURE DETERMINATION AT 2.5 A RESOLUTION

The crystal structure of beta-lactamase TEM1 from E. coli has been solved to 2.5 angstrom resolution by X-ray diffraction methods and refined to a crystallographic R-factor of 22.7%. The structure was determined by multiple isomorphous replacement using four heavy atom derivatives. The solution from molecular replacement, using a polyalanine model constructed from the C(alpha) coordinates of S. Aureus PC1 enzyme, provided a set of phases used for heavy atom derivatives analysis. The E. coli beta-lactamase TEM1 is made up of two domains whose topology is similar to that of the PC1 enzyme. However, global superposition of the two proteins shows significant differences.