title: Interaction of N-methyl-2-alkenyl-4-quinolones with ATP-dependent MurE ligase of Mycobacterium tuberculosis: antibacterial activity, molecular docking and inhibition kinetics.
abstract: OBJECTIVE
  The aim of this study was to comprehensively evaluate the antibacterial activity and MurE inhibition of a set of N-methyl-2-alkenyl-4-quinolones found to inhibit the growth of fast-growing mycobacteria.
  
  
  METHODS
  Using the spot culture growth inhibition assay, MICs were determined for Mycobacterium tuberculosis H(37)Rv, Mycobacterium bovis BCG and Mycobacterium smegmatis mc(2)155. MICs were determined for Mycobacterium fortuitum, Mycobacterium phlei, methicillin-resistant Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa using microplate dilution assays. Inhibition of M. tuberculosis MurE ligase activity was determined both by colorimetric and HPLC methods. Computational modelling and binding prediction of the quinolones in the MurE structure was performed using Glide. Kinetic experiments were conducted for understanding possible competitive relations of the quinolones with the endogenous substrates of MurE ligase.
  
  
  RESULTS
  The novel synthetic N-methyl-2-alkenyl-4-quinolones were found to be growth inhibitors of M. tuberculosis and rapid-growing mycobacteria as well as methicillin-resistant S. aureus, while showing no inhibition for E. coli and P. aeruginosa. The quinolones were found to be inhibitory to MurE ligase of M. tuberculosis in the micromolar range (IC(50) ∼40-200 μM) when assayed either spectroscopically or by HPLC. Computational docking of the quinolones on the published M. tuberculosis MurE crystal structure suggested that the uracil recognition site is a probable binding site for the quinolones.
  
  
  CONCLUSIONS
  N-methyl-2-alkenyl-4-quinolones are inhibitors of mycobacterial and staphylococcal growth, and show MurE ligase inhibition. Therefore, they are considered as a starting point for the development of increased affinity MurE activity disruptors.
authors.affiliation: Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK.
authors.forename: Juan David
authors.initials: JD
authors.lastname: Guzman
authors.forename: Abraham
authors.initials: A
authors.lastname: Wube
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Evangelopoulos
authors.forename: Antima
authors.initials: A
authors.lastname: Gupta
authors.forename: Antje
authors.initials: A
authors.lastname: Hüfner
authors.forename: Chandrakala
authors.initials: C
authors.lastname: Basavannacharya
authors.forename: Md Mukhleshur
authors.initials: MM
authors.lastname: Rahman
authors.forename: Christina
authors.initials: C
authors.lastname: Thomaschitz
authors.forename: Rudolf
authors.initials: R
authors.lastname: Bauer
authors.forename: Timothy Daniel
authors.initials: TD
authors.lastname: McHugh
authors.forename: Irene
authors.initials: I
authors.lastname: Nobeli
authors.forename: Jose M
authors.initials: JM
authors.lastname: Prieto
authors.forename: Simon
authors.initials: S
authors.lastname: Gibbons
authors.forename: Franz
authors.initials: F
authors.lastname: Bucar
authors.forename: Sanjib
authors.initials: S
authors.lastname: Bhakta
mesh_terms: D042462:4-Quinolones / Q000737:chemistry / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D006801:Humans; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009161:Mycobacterium / Q000187:drug effects* / Q000201:enzymology* / Q000254:growth & development; D010453:Peptide Synthases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
chemical_list: D042462:4-Quinolones; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D010453:Peptide Synthases; C554750:MurE protein, Mycobacterium tuberculosis