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A new class of antibacterials, the imidazopyrazinones, reveal structural transitions involved in DNA gyrase poisoning and mechanisms of resistance

DOI: 10.1093/nar/gky181 DOI Help

Authors: Thomas Germe (John Innes Centre) , Judit Voros (John Innes Centre) , Frederic Jeannot (Sanofi R&D) , Thomas Taillier (Sanofi R&D) , Robert A. Stavenger (GlaxoSmithKline) , Eric Bacqué (Sanofi R&D) , Anthony Maxwell (John Innes Centre) , Benjamin D. Bax (GlaxoSmithKline)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Nucleic Acids Research , VOL 16

State: Published (Approved)
Published: March 2018
Diamond Proposal Number(s): 5799

Open Access Open Access

Abstract: Imidazopyrazinones (IPYs) are a new class of compounds that target bacterial topoisomerases as a basis for their antibacterial activity. We have characterized the mechanism of these compounds through structural/mechanistic studies showing they bind and stabilize a cleavage complex between DNA gyrase and DNA (‘poisoning’) in an analogous fashion to fluoroquinolones, but without the requirement for the water–metal–ion bridge. Biochemical experiments and structural studies of cleavage complexes of IPYs compared with an uncleaved gyrase–DNA complex, reveal conformational transitions coupled to DNA cleavage at the DNA gate. These involve movement at the GyrA interface and tilting of the TOPRIM domains toward the scissile phosphate coupled to capture of the catalytic metal ion. Our experiments show that these structural transitions are involved generally in poisoning of gyrase by therapeutic compounds and resemble those undergone by the enzyme during its adenosine triphosphate-coupled strand-passage cycle. In addition to resistance mutations affecting residues that directly interact with the compounds, we characterized a mutant (D82N) that inhibits formation of the cleavage complex by the unpoisoned enzyme. The D82N mutant appears to act by stabilizing the binary conformation of DNA gyrase with uncleaved DNA without direct interaction with the compounds. This provides general insight into the resistance mechanisms to antibiotics targeting bacterial type II topoisomerases.

Diamond Keywords: Bacteria; Enzymes

Subject Areas: Biology and Bio-materials, Medicine, Chemistry

Instruments: I03-Macromolecular Crystallography

Other Facilities: ESRF

Added On: 04/04/2018 12:01


Discipline Tags:

Pathogens Antibiotic Resistance Infectious Diseases Health & Wellbeing Biochemistry Chemistry Structural biology Drug Discovery Life Sciences & Biotech

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