Paper Citing NAMD - Abstract
Heidarsson, Petur O.; Otazo, Mariela R.; Bellucci, Luca; Mossa, Alessandro; Imparato, Alberto; Paci, Emanuele; Corni, Stefano; Di Felice, Rosa; Kragelund, Birthe B.; Cecconi, Ciro
Single-Molecule Folding Mechanism of an EF-Hand Neuronal Calcium Sensor
STRUCTURE, 21:1812-1821, OCT 8 2013
EF-hand calcium sensors respond structurally to changes in intracellular Ca2+ concentration, triggering diverse cellular responses and resulting in broad interactomes. Despite impressive advances in decoding their structure-function relationships, the folding mechanism of neuronal calcium sensors is still elusive. We used single-molecule optical tweezers to study the folding mechanism of the human neuronal calcium sensor 1 (NCS1). Two intermediate structures induced by Ca2+ binding to the EF-hands were observed during refolding. The complete folding of the C domain is obligatory for the folding of the N domain, showing striking interdomain dependence. Molecular dynamics results reveal the atomistic details of the unfolding process and rationalize the different domain stabilities during mechanical unfolding. Through constant-force experiments and hidden Markov model analysis, the free energy landscape of the protein was reconstructed. Our results emphasize that NCS1 has evolved a remarkable complex interdomain cooperativity and a fundamentally different folding mechanism compared to structurally related proteins.
