Single-molecule folding mechanism of an EF-hand neuronal calcium sensor

TY - JOUR

T1 - Single-molecule folding mechanism of an EF-hand neuronal calcium sensor

AU - Heiðarsson, Pétur Orri

AU - Otazo, Mariela R.

AU - Bellucci, Luca

AU - Mossa, Alessandro

AU - Imparato, Alberto

AU - Paci, Emanuele

AU - Corni, Stefano

AU - Felice, Rosa Di

AU - Kragelund, Birthe Brandt

AU - Cecconi, Ciro

PY - 2013/10/8

Y1 - 2013/10/8

N2 - 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.

AB - 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.

U2 - 10.1016/j.str.2013.07.022

DO - 10.1016/j.str.2013.07.022

M3 - Journal article

C2 - 24012477

SN - 0969-2126

VL - 21

SP - 1812

EP - 1821

JO - Structure

JF - Structure

IS - 10

ER -