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Journal of Bacteriology, October 2003, p. 6137-6146, Vol. 185, No. 20
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.20.6137-6146.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

ATP-Bound Conformation of Topoisomerase IV: a Possible Target for Quinolones in Streptococcus pneumoniae

Farid Sifaoui,1 Valérie Lamour,2 Emmanuelle Varon,1 Dino Moras,2 and Laurent Gutmann1*

INSERM E0004, Laboratoire de Recherche Moléculaire sur les Antibiotiques, UFR Broussais-Hôtel-Dieu, Université Paris VI, 75270 Paris Cedex 06,1 Institut de Génétique et de Biologie Moléculaire et Cellulaire, UMR7104 CNRS/INSERM, Université Louis Pasteur, 67404 Illkirch Cedex, France2

Received 17 March 2003/ Accepted 7 July 2003

Topoisomerase IV, a C2E2 tetramer, is involved in the topological changes of DNA during replication. This enzyme is the target of antibacterial compounds, such as the coumarins, which target the ATP binding site in the ParE subunit, and the quinolones, which bind, outside the active site, to the quinolone resistance-determining region (QRDR). After site-directed and random mutagenesis, we found some mutations in the ATP binding site of ParE near the dimeric interface and outside the QRDR that conferred quinolone resistance to Streptococcus pneumoniae, a bacterial pathogen. Modeling of the N-terminal, 43-kDa ParE domain of S. pneumoniae revealed that the most frequent mutations affected conserved residues, among them His43 and His103, which are involved in the hydrogen bond network supporting ATP hydrolysis, and Met31, at the dimeric interface. All mutants showed a particular phenotype of resistance to fluoroquinolones and an increase in susceptibility to novobiocin. All mutations in ParE resulted in resistance only when associated with a mutation in the QRDR of the GyrA subunit. Our models of the closed and open conformations of the active site indicate that quinolones preferentially target topoisomerase IV of S. pneumoniae in its ATP-bound closed conformation.

* Corresponding author. Mailing address: INSERM E0004, Laboratoire de Recherche Moléculaire sur les Antibiotiques, 15 Rue de l'Ecole de Médecine, Université Paris VI, 75270 Paris Cedex 06, France. Phone: 33-1-42-34-68-63. Fax: 33-1-43-25-68-12. E-mail: gutmann{at}ccr.jussieu.fr.

Journal of Bacteriology, October 2003, p. 6137-6146, Vol. 185, No. 20
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.20.6137-6146.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Dupont, P., Aubry, A., Cambau, E., Gutmann, L. (2005). Contribution of the ATP Binding Site of ParE to Susceptibility to Novobiocin and Quinolones in Streptococcus pneumoniae. J. Bacteriol. 187: 1536-1540 [Abstract] [Full Text]  


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