The crystal structure of the H116Q mutant of NDM-1: An enzyme devoid of zinc ions

Wai Po Kong, Kwok Yin Wong, Yu Wai Chen

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

New Delhi metallo-β-lactamase 1 (NDM-1) is an important causative factor of antimicrobial resistance due to its efficient hydrolysis of a broad range of β-lactam compounds. The two zinc ions at the active site play essential roles in the NDM-1 catalytic activities. In a previous work, H116, one of the three ligands at the Zn1 site, was mutated in order to investigate the nature of zinc ion chelation. We report here the crystal structure of the NDM-1 H116Q mutant, that was designed to convert a B1 di-zinc enzyme into a B3 type, which either still binds two zinc ions or binds only one at the Zn2 site. The effect of mutation on the overall structure is minimal. Unexpectedly, no zinc ion was observed in the crystal structure. The Zn2-site ligating residue C221 forms a covalent bond with the nearby K121, a residue important in maintaining the active-site structure. The largest conformational changes were found at main-chain and side-chain atoms at residues 232–236 (loop 10), the proper configuration of which is known to be essential for substrate binding. The catalytic-site mutation caused little local changes, yet the effects were amplified and propagated to the substrate binding residues. There were big changes in the ψ angles of residues G232 and L234, which resulted in the side chain of N233 being displaced away from the substrate-binding site. In summary, we failed in turning a B1 enzyme into a B3 enzyme, yet we produced a zinc-less NDM-1 with residual activities.

Original languageEnglish
Article number107922
JournalJournal of Structural Biology
Volume214
Issue number4
DOIs
Publication statusPublished - Dec 2022

Keywords

  • Active site mutation
  • NOS linkage
  • Sulfenamide bond
  • Zinc ions, antibiotic resistance

ASJC Scopus subject areas

  • Structural Biology

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