1. Department of Condensed Matter Physics, University of Barcelona, Carrer Martí i Franqués 1, 08028 Barcelona, Spain
2. Faculty of Biosciences, Heidelberg University, Im Neuenheimer Feld 234, 69120 Heidelberg, Germany
3. Molecular Biology Institute of Barcelona (IBMB-CSIC, Maria de Maeztu Unit of Excellence), Carrer Baldiri Reixac 4-8, 08028 Barcelona, Spain