title: Structure of the N-terminal segment of human retinol dehydrogenase 11 and its preferential lipid binding using model membranes.
abstract: Retinol dehydrogenase 11 (RDH11) has been postulated to be anchored to membranes by means of its N-terminal segment in retinal pigment epithelial (RPE) cells where it participates to the visual cycle. The analysis of the primary sequence of RDH11 revealed that its N-terminal hydrophobic segment could be involved in the anchoring of this enzyme to membranes. However, no information is yet available on the properties of this N-terminal segment to support this role. The secondary structure and membrane binding of two N-terminal peptides of RDH11 with different lengths have thus been investigated to provide this information. Online tools allowed predicting an α-helical secondary structure for both peptides. Infrared spectroscopy and circular dichroism have shown that the α-helix of the Long-peptide (35 amino acids) is longer and more rigid than that of the Short-peptide (25 amino acids) regardless of the type of solvent. Langmuir monolayers have been used as a model membrane to study lipid-peptide interactions. Values of maximum insertion pressure and synergy suggested a preferential binding of the Long-peptide to lipids with a phosphoethanolamine polar head group, which are abundant in the RPE. Furthermore, infrared spectroscopy in monolayers has shown that the α-helical structure of the Long-peptide is more stable in the presence of saturated phospholipids whereas the structure of the Short-peptide is mainly disordered. Altogether, the present data demonstrate that the α-helical hydrophobic core of the N-terminal segment of RDH11 displays properties typical of transmembrane domains, in agreement with its postulated role in the membrane anchoring of this protein.
authors.affiliation: CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
authors.forename: Mustapha
authors.initials: M
authors.lastname: Lhor
authors.affiliation: CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
authors.forename: Mario
authors.initials: M
authors.lastname: Méthot
authors.affiliation: CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
authors.forename: Habib
authors.initials: H
authors.lastname: Horchani
authors.affiliation: CUO-Recherche, Hôpital du Saint-Sacrement, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada. Electronic address: christian.salesse@fmed.ulaval.ca.
authors.forename: Christian
authors.initials: C
authors.lastname: Salesse
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012997:Solvents / Q000737:chemistry; D013055:Spectrophotometry, Infrared
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D008051:Lipid Bilayers; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D012997:Solvents; C042511:1,2-dioleoylphosphatidylserine; D010088:Oxidoreductases; C422653:RDH11 protein, human; C017251:1,2-oleoylphosphatidylcholine
keywords: Maximum insertion pressure; N-terminal anchoring peptide; Protein secondary structure; Retinal pigment epithelium; Retinol dehydrogenase 11; monolayer