FIGURE 1.

Alignment of the four class A β-lactamases used in this study and cartoon representation of BLIP-II-β-lactamase complexes. A, a sequence alignment of the loop-helix region (residues 99–114 based on the β-lactamase ambler numbering scheme) is shown (13). The sequence alignment was performed, and the identities were determined using ClustalW (34). The amino acid identity was determined when compared with TEM-1. However, all of the β-lactamases used in this study are not more than 52% identical to one another. B, the BLIP-II-TEM-1 (red; Protein Data Bank code 1JTD) and BLIP-II-Bla1 (cyan; Protein Data Bank code 3QHY) structures are shown with the catalytic serine depicted as a yellow sphere (27, 28). The loop-helix domain of β-lactamase is shown in blue.