Calcium Sensing by Recoverin: Effect of Protein Conformation on Ion Affinity

The detailed functional mechanism of recoverin, which acts as a myristoyl switch at the rod outer-segment disk membrane, is elucidated by direct and replica-exchange molecular dynamics. In accord with NMR structural evidence and calcium binding assays, simulations point to the key role of enhanced c...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2018-04, Vol.9 (7), p.1613-1619
Main Authors: Timr, Štěpán, Kadlec, Jan, Srb, Pavel, Ollila, O. H. Samuli, Jungwirth, Pavel
Format: Article
Language:English
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Summary:The detailed functional mechanism of recoverin, which acts as a myristoyl switch at the rod outer-segment disk membrane, is elucidated by direct and replica-exchange molecular dynamics. In accord with NMR structural evidence and calcium binding assays, simulations point to the key role of enhanced calcium binding to the EF3 loop of the semiopen state of recoverin as compared to the closed state. This 2–4-order decrease in calcium dissociation constant stabilizes the semiopen state in response to the increase of cytosolic calcium concentration in the vicinity of recoverin. A second calcium ion then binds to the EF2 loop and, consequently, the structure of the protein changes from the semiopen to the open state. The latter has the myristoyl chain extruded to the cytosol, ready to act as a membrane anchor of recoverin.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.8b00495