1. Laboratorio de Estudios Cristalográficos, IACT, CSIC, Universidad de Granada, P.T. Ciencias de la Salud, Avenida del conocimiento s/n, 18100 Armilla, Granada, Spain, Institute for Materials Research, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577, Japan, Ultrastructure, Flanders Interuniversity Institute for Biotechnology (VIB), Vrije Universiteit, Brussel, Belgium, and Graduate School of Science, Tohoku University, Aza-Aoba, Aramaki, Sendai 980-8578, Japan