9KGT | pdb_00009kgt

Crystal structure of topoisomerase IV from Klebsiella pneumoniae in complex with DNA and BWC0977, a dual-targeting broad-spectrum novel bacterial topoisomerase inhibitor.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.05 Å
  • R-Value Free: 
    0.269 (Depositor), 0.270 (DCC) 
  • R-Value Work: 
    0.223 (Depositor), 0.223 (DCC) 
  • R-Value Observed: 
    0.226 (Depositor) 

Starting Model: experimental
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This is version 1.2 of the entry. See complete history


Literature

Structural interactions of BWC0977 with Klebsiella pneumoniae topoisomerase IV and biochemical basis of its broad-spectrum activity.

Nandishaiah, R.Murakami, S.Hameed P, S.Aoki, M.Okada, U.Yamashita, E.Venkatesan, S.Bharatham, N.Sarma, S.Shanbhag, A.P.Sharma, S.Rao, R.Ramachandran, V.Balasubramanian, V.Datta, S.Katagihallimath, N.

(2025) Commun Biol 8: 1666-1666

  • DOI: https://doi.org/10.1038/s42003-025-09055-y
  • Primary Citation of Related Structures:  
    9KGT

  • PubMed Abstract: 

    Antimicrobial resistance is a growing global health crisis driving the urgent need for effective broad-spectrum antibiotics. BWC0977 is a pyrazino-oxazinone based novel bacterial topoisomerase inhibitor (NBTI) currently in Phase 1 clinical trials and demonstrates potent activity against multidrug-resistant Gram-negative and Gram-positive bacteria. It targets both DNA gyrase and topoisomerase IV with balanced low-nanomolar potencies, showing remarkable superiority over ciprofloxacin and gepotidacin. We report the first 3.05 Å cocrystal structure of BWC0977 bound to Klebsiella pneumoniae topoisomerase IV, revealing its binding mode and interaction residues. The reduced inhibition of BWC0977 against purified gyrase enzymes carrying an individual mutation at these residues supports the relevance of these molecular interactions. Mutational analyses in Escherichia coli strains show that single target mutations in gyrA or parC do not confer resistance, while simultaneous mutations in both genes result in over 250-fold reduced susceptibility. The compound also demonstrates more than 5000-fold selectivity for bacterial over human topoisomerases and retains efficacy against fluoroquinolone and carbapenem-resistant clinical isolates. Together, these structural, biochemical, and microbiological insights elucidate BWC0977's broad-spectrum antibacterial activity and reduced vulnerability to resistance, establishing it as a promising next-generation antibiotic to address the global threat of antimicrobial resistance.


  • Organizational Affiliation
    • Bugworks Research India Pvt. Ltd., Center for Cellular & Molecular Platforms, National Center for Biological Sciences, Bangalore, India.

Macromolecules

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA topoisomerase 4 subunit B,DNA topoisomerase 4 subunit A
A, B, C, D
734Klebsiella pneumoniae subsp. pneumoniae MGH 78578Mutation(s): 0 
Gene Names: parEKPN_03444parCKPN_03437
EC: 5.6.2.2
UniProt
Find proteins for A6TE19 (Klebsiella pneumoniae subsp. pneumoniae (strain ATCC 700721 / MGH 78578))
Explore A6TE19 
Go to UniProtKB:  A6TE19
Find proteins for A6TE12 (Klebsiella pneumoniae subsp. pneumoniae (strain ATCC 700721 / MGH 78578))
Explore A6TE12 
Go to UniProtKB:  A6TE12
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupsA6TE19A6TE12
Sequence Annotations
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  • Reference Sequence
Find similar nucleic acids by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains LengthOrganismImage
DNA (5'-D(P*TP*TP*AP*CP*GP*TP*TP*GP*TP*AP*TP*GP*AP*TP*CP*AP*TP*AP*CP*AP*AP*CP*GP*TP*AP*A)-3')
E, F, G, H
26synthetic construct
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
A1L5V (Subject of Investigation/LOI)
Query on A1L5V

Download Ideal Coordinates CCD File 
I [auth F],
J [auth H]
6-[(5S)-5-[[[2-(7-Fluoro-1,2-dihydro-1-methyl-2-oxo-8-quinolinyl)ethyl]amino]methyl]-2-oxo-3-oxazolidinyl]-2H-pyrazino[2,3-b]-1,4-oxazin-3(4H)-one
C22 H21 F N6 O5
MKICNOUBIXXGPQ-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.05 Å
  • R-Value Free:  0.269 (Depositor), 0.270 (DCC) 
  • R-Value Work:  0.223 (Depositor), 0.223 (DCC) 
  • R-Value Observed: 0.226 (Depositor) 
Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 95.444α = 90
b = 163.265β = 94.548
c = 145.842γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XSCALEdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Japan Society for the Promotion of Science (JSPS)Japan--

Revision History  (Full details and data files)

  • Version 1.0: 2025-11-12
    Type: Initial release
  • Version 1.1: 2025-12-03
    Changes: Database references
  • Version 1.2: 2025-12-10
    Changes: Database references