About the Authors

Lei Wang

Affiliation Structural Biology Laboratory, The Salk Institute, La Jolla, California, United States of America

Samir K Maji

Affiliation Structural Biology Laboratory, The Salk Institute, La Jolla, California, United States of America

Michael R Sawaya

Affiliations Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, California, United States of America , University of California, Los Angeles–Department of Energy (UCLA-DOE) Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, United States of America

David Eisenberg

Affiliations Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, California, United States of America , University of California, Los Angeles–Department of Energy (UCLA-DOE) Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California, United States of America

Roland Riek

To whom correspondence should be addressed. E-mail: roland.riek@phys.chem.ethz.ch

Affiliations Structural Biology Laboratory, The Salk Institute, La Jolla, California, United States of America , Laboratory of Physical Chemistry, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

LW and RR conceived and designed the experiments. LW, SM, and MRS performed the experiments. LW, SM, MRS, DE, and RR analyzed the data. LW, DE, and RR wrote the paper.