1. School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2. Laboratoire de Biologie Structurale de la Cellule (BIOC), Ecole Polytechnique, CNRS-UMR7654, Institut Polytechnique de Paris, Palaiseau 91128, France
3. NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore