1. Institute of Infectious Diseases and Molecular Medicine, Division of Chemical Pathology, and National Health Laboratory Services, University of Cape Town, South Africa, CNRS, URA 2096 (Protéines Membranaires Transductrices d'Énergie), F-91191 Gif-sur-Yvette, France, and CEA, iBiTec-S (Institut de Biologie et Technologies de Saclay), F-91191 Gif-sur-Yvette, France