Structure of the plasmid-mediated class C β-lactamase ACT-1

The crystallographic structure of ACT-1, which is the first plasmid-mediated AmpC-type β-lactamase to have been completely analyzed in terms of nucleotide sequence and which has a high degree of sequence similarity to the chromosomal AmpC enzymes of Enterobacter cloacae and the plasmid-encoded MIR-1, has been solved at 2.4 Å resolution. The overall structure of ACT-1 is similar to those of other class C β-lactamases, such as the AmpC enzymes from E. cloacae P99 and Escherichia coli.