The complex folding network of single calmodulin molecules.
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.
Physik Department E22, Technische Universität München, James-Franck-Strasse, 85748 Garching, Germany.
Johannes
J
Stigler
Fabian
F
Ziegler
Anja
A
Gieseke
J Christof M
JC
Gebhardt
Matthias
M
Rief
D002118:Calcium / Q000737:chemistry; D002147:Calmodulin / Q000737:chemistry*; D007700:Kinetics; D008390:Markov Chains; D052898:Optical Tweezers; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D002147:Calmodulin; D002118:Calcium