Phosphatidylserine Allows Observation of the Calcium-Myristoyl Switch of Recoverin and Its Preferential Binding.
Recoverin undergoes a calcium-myristoyl switch during visual phototransduction. Indeed, calcium binding by recoverin results in the extrusion of its myristoyl group, which allows its membrane binding. However, the contribution of particular lipids and of specific amino acids of recoverin in its membrane binding has not yet been demonstrated. In the present work, the affinity of recoverin for the negatively charged phosphatidylserine has been clearly shown to be governed by a cluster of positively charged residues located in its N-terminal segment. Moreover, the calcium-myristoyl switch of recoverin was only observed upon binding onto monolayers of phosphatidylserine and not in the case of other anionic phospholipids. Fluorescence microscopy experiments with mixed lipid monolayers allowed confirmation of the specific binding of myristoylated recoverin to phosphatidylserine, whereas the extent of penetration of recoverin in phosphatidylserine monolayers was estimated by ellipsometry. A model has thus been proposed for the membrane binding of myristoylated recoverin in the presence of calcium.
CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de Médecine, and Regroupement stratégique PROTEO, Université Laval , Québec, Québec, G1S 4L8 Canada.
Philippe
P
Calvez
CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de Médecine, and Regroupement stratégique PROTEO, Université Laval , Québec, Québec, G1S 4L8 Canada.
Thaís F
TF
Schmidt
CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de Médecine, and Regroupement stratégique PROTEO, Université Laval , Québec, Québec, G1S 4L8 Canada.
Line
L
Cantin
CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de Médecine, and Regroupement stratégique PROTEO, Université Laval , Québec, Québec, G1S 4L8 Canada.
Kristina
K
Klinker
CUO-Recherche, Centre de recherche du CHU de Québec, Hôpital du Saint-Sacrement, Département d'ophtalmologie, Faculté de Médecine, and Regroupement stratégique PROTEO, Université Laval , Québec, Québec, G1S 4L8 Canada.
Christian
C
Salesse