1. Department of Physical Chemistry and Soft Matter, Wageningen University and Research, Wageningen 6078 WE, The Netherlands
2. Department of Biochemistry, University of Washington, Seattle, WA 98195
3. Institute for Protein Design, University of Washington, Seattle, WA 98195
4. Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
5. HHMI, Seattle, WA 98195