1. School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
2. NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore
3. School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), No. 2001 Longxiang Boulevard, Longgang District, Shenzhen, Guangdong 518172, P. R. China