The Complex Folding Network of Single Calmodulin Molecules

1. Johannes Stigler, 
2. Fabian Ziegler, 
3. Anja Gieseke, 
4. J. Christof M. Gebhardt, 
5. Matthias Rief

1. 
   

Direct observation of the detailed conformational fluctuations of a single protein molecule en route to its folded state has so far been realized only in silico. We have used single-molecule force spectroscopy to study the folding transitions of single calmodulin molecules. High-resolution optical tweezers assays in combination with hidden Markov analysis reveal a complex network of on- and off-pathway intermediates. Cooperative and anticooperative interactions across domain boundaries can be observed directly. The folding network involves four intermediates. Two off-pathway intermediates exhibit non-native interdomain interactions and compete with the ultrafast productive folding pathway.


DOI


Journal: Science