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Journal of Bacteriology, March 2009, p. 1587-1594, Vol. 191, No. 5
0021-9193/09/$08.00+0     doi:10.1128/JB.01205-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

The Pentapeptide Repeat Proteins MfpAMt and QnrB4 Exhibit Opposite Effects on DNA Gyrase Catalytic Reactions and on the Ternary Gyrase-DNA-Quinolone Complex{triangledown} ,{dagger}

Audrey Mérens,1,2,3 Stéphanie Matrat,4 Alexandra Aubry,4,5,6 Christine Lascols,1 Vincent Jarlier,4,5,6 Claude-James Soussy,1,7 Jean-Didier Cavallo,2,3 and Emmanuelle Cambau1,6,7*

Université Paris 12, IFR10, Bacteriologie, Créteil F-94010, France,1 Hôpital d'Instruction des Armées Bégin, Laboratoire de Biologie, Saint-Mandé, France,2 Ecole du Val-de-Grâce, Paris, France,3 Université Pierre et Marie Curie-Paris 6, EA1541 Paris, France,4 AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Service Bactériologie, Paris, France,5 Centre National de Référence des Mycobactéries et de la Résistance des Mycobactéries aux Antituberculeux, Paris, France,6 AP-HP, Groupe Hospitalier Albert Chenevier-Henri Mondor, Service Bactériologie, Créteil, F-94010, France7

Received 27 August 2008/ Accepted 30 November 2008

MfpAMt and QnrB4 are two newly characterized pentapeptide repeat proteins (PRPs) that interact with DNA gyrase. The mfpAMt gene is chromosome borne in Mycobacterium tuberculosis, while qnrB4 is plasmid borne in enterobacteria. We expressed and purified the two PRPs and compared their effects on DNA gyrase, taking into account host specificity, i.e., the effect of MfpAMt on M. tuberculosis gyrase and the effect of QnrB4 on Escherichia coli gyrase. Whereas QnrB4 inhibited E. coli gyrase activity only at concentrations higher than 30 µM, MfpAMt inhibited all catalytic reactions of the M. tuberculosis gyrase described for this enzyme (supercoiling, cleavage, relaxation, and decatenation) with a 50% inhibitory concentration of 2 µM. We showed that the D87 residue in GyrA has a major role in the MfpAMt-gyrase interaction, as D87H and D87G substitutions abolished MfpAMt inhibition of M. tuberculosis gyrase catalytic reactions, while A83S modification did not. Since MfpAMt and QnrB4 have been involved in resistance to fluoroquinolones, we measured the inhibition of the quinolone effect in the presence of each PRP. QnrB4 reversed quinolone inhibition of E. coli gyrase at 0.1 µM as described for other Qnr proteins, but MfpAMt did not modify M. tuberculosis gyrase inhibition by fluoroquinolones. Crossover experiments showed that MfpAMt also inhibited E. coli gyrase function, while QnrB4 did not reverse quinolone inhibition of M. tuberculosis gyrase. In conclusion, our in vitro experiments showed that MfpAMt and QnrB4 exhibit opposite effects on DNA gyrase and that these effects are protein and species specific.

* Corresponding author. Mailing address: Hôpital Saint Louis (AP-HP), Laboratoire de Bactériologie-Virologie-Hygiène, Hôpital Saint Louis, 1 avenue Claude Vellefaux, 75475 Paris Cedex 10, France. Phone: 33 1 42 49 94 93. Fax: 33 1 42 49 92 00. E-mail: emmanuelle.cambau{at}sls.aphp.fr

{triangledown} Published ahead of print on 5 December 2008.

{dagger} Supplemental material for this article may be found at http://jb.asm.org/.

Journal of Bacteriology, March 2009, p. 1587-1594, Vol. 191, No. 5
0021-9193/09/$08.00+0     doi:10.1128/JB.01205-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Strahilevitz, J., Jacoby, G. A., Hooper, D. C., Robicsek, A. (2009). Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat. Clin. Microbiol. Rev. 22: 664-689 [Abstract] [Full Text]  


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