Structural and mutagenic analysis of metallo-β-lactamase IMP-18

Takamitsu Furuyama, Haruka Nonomura, Yoshikazu Ishii, Nancy D. Hanson, Akiko Shimizu-Ibuka

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


IMP-type metallo-β-lactamases (MBLs) are exogenous zinc metalloenzymes that hydrolyze a broad range of β-lactams, including carbapenems. Here we report the crystal structure of IMP-18, an MBL cloned from Pseudomonas aeruginosa, at 2.0-Å resolution. The overall structure of IMP-18 resembles that of IMP-1, with an αβ/βα "folded sandwich" configuration, but the loop that covers the active site has a distinct conformation. The relationship between IMP-18's loop conformation and its kinetic properties was investigated by replacing the amino acid residues that can affect the loop conformation (Lys44, Thr50, and Ile69) in IMP-18 with those occupying the corresponding positions in the well-described enzyme IMP-1. The replacement of Thr50 with Pro considerably modified IMP-18's kinetic properties, specifically those pertaining to meropenem, with the kcat/Km value increased by an order of magnitude. The results indicate that this is a key residue that defines the kinetic properties of IMP-type β-lactamases.

Original languageEnglish (US)
Pages (from-to)5521-5526
Number of pages6
JournalAntimicrobial agents and chemotherapy
Issue number9
StatePublished - Sep 1 2016

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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