FIG. 3.

Multiple sequence alignment of the amino acid sequences of CARB-1, CARB-2, CARB-3, CARB-4, P. mirabilis N29, P. mirabilis GN79, and CARB-6 β-lactamases. The shadowed boxes (I to VII) correspond to amino acid boxes conserved in all penicillin-recognizing enzymes, as identified by Joris et al. (14). Alpha-helix and beta-barrel motifs are indicated from the PC-1 crystal structure (4, 12). Asterisks indicate the conserved residues specific for class A β-lactamases. Amino acid changes are written as black letters in white boxes. Sequences are numbered as described by Ambler (2).