1. Laboratoire International Associé Centre National de la Recherche Scientifique et University of Illinois at Urbana−Champaign, Unité Mixte de Recherche n°7019, Université de Lorraine, B.P. 70239, 54506 Vandœuvre-lès-Nancy cedex, France
2. Theoretical and Computational Biophysics Group, Beckman Institute, and Department of Physics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
3. Department of Biochemistry and Molecular Biology, The University of Chicago, 929 E. 57th Street W225, Chicago, Illinois 60637, United States