FIG. 1.

Multiple amino acid sequence alignment of the AmpC β-lactamases of the following strains: 1, E. aerogenes 97B (accession no. AF211348); 2, E. aerogenes EarCOL; 3, E. aerogenes Ear1; 4, E. aerogenes Ear2. Dashes indicate identical amino acids. Conserved residues of class C β-lactamases are underlined. The amino acid substitution in the Ear2 sequence is shown in boldface. Amino acids are numbered in accordance with the conventional numbering of E. cloacae P99, with the active-site serine at position 64.