Structure of AmpC β-lactamase (AmpC^D) from an Escherichia coli clinical isolate with a tripeptide deletion (Gly286-Ser287-Asp288) in the H10 helix

The X-ray crystal structure of AmpC β-lactamase (AmpC^D) with a tripeptide deletion (Gly286-Ser287-Asp288) produced by Escherichia coli HKY28, a ceftazidime-resistant strain, was determined at a resolution of 1.7 Å. The structure of AmpC^D suggests that the tripeptide deletion at positions 286–288 located in the H10 helix causes a structural change of the Asn289–Asn294 region from the α-helix present in the native AmpC β-lactamase of E. coli to a loop structure, which results in a widening of the substrate-binding site.