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Journal of Biomedicine and Biotechnology
Volume 2006 (2006), Article ID 80101, 8 pages
Research Article

Site-Directed Mutagenesis to Assess the Binding Capacity of Class S Protein of Staphylococcus aureus Leucotoxins to the Surface of Polymorphonuclear Cells

1Département de Biochimie et de Biologie Moléculaire, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Cotonou BP 04-0320, Benin
2Laboratoire de Physiopathologie et d'Antibiologie Bactériennes des Infections Emergentes et Nosocomiales, UPRES EA 3432, Institut de Bactériologie de la Faculté de Médecine de Strasbourg, Hôpitaux Universitaires de Strasbourg, Université Louis Pasteur, 3 rue Koeberlé, Strasbourg 67000, France
3CNR—ITC, Istituto di BioFisica, Università di Trento, Via Sommarive, Trento 18 38050, Italy

Received 13 August 2005; Revised 30 November 2005; Accepted 4 December 2005

Copyright © 2006 L. Baba Moussa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Staphylococcal leucotoxins result from the association of class S components and class F component inducing the activation and the permeabilization of the target cells. Like α-toxin, the leucotoxins are pore-forming toxins with more than 70% β-sheet. This was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. In addition, threonine 28 of a predicted and conserved β-sheet at the N-terminal extremity of class S proteins composing leucotoxins aligns with histidine 35 of α-toxin, which has a key role in oligomerization of the final pore. Flow cytometry was used to study different aminoacid substitutions of the threonine 28 in order to evaluate its role in the biological activity of these class S proteins. Finally, results show that threonine 28 of the leucotoxin probably plays a role similar to that of histidine 35 of α-toxin. Mutations on this threonin largely influenced the secondary interaction of the class F component and led to inactive toxin.