RT Journal Article
SR Electronic
T1 An inducible amphipathic α-helix mediates subcellular targeting and membrane binding of RPE65
JF Life Science Alliance
JO Life Sci. Alliance
FD Life Science Alliance LLC
SP e202201546
DO 10.26508/lsa.202201546
VO 6
IS 1
A1 Sheetal Uppal
A1 Tingting Liu
A1 Emily Galvan
A1 Fatima Gomez
A1 Tishina Tittley
A1 Eugenia Poliakov
A1 Susan Gentleman
A1 T Michael Redmond
YR 2023
UL https://www.life-science-alliance.org/content/6/1/e202201546.abstract
AB RPE65 retinol isomerase is an indispensable player in the visual cycle between the vertebrate retina and RPE. Although membrane association is critical for RPE65 function, its mechanism is not clear. Residues 107–125 are believed to interact with membranes but are unresolved in all RPE65 crystal structures, whereas palmitoylation at C112 also plays a role. We report the mechanism of membrane recognition and binding by RPE65. Binding of aa107–125 synthetic peptide with membrane-mimicking micellar surfaces induces transition from unstructured loop to amphipathic α-helical (AH) structure but this transition is automatic in the C112-palmitoylated peptide. We demonstrate that the AH significantly affects palmitoylation level, membrane association, and isomerization activity of RPE65. Furthermore, aa107–125 functions as a membrane sensor and the AH as a membrane-targeting motif. Molecular dynamic simulations clearly show AH-membrane insertion, supporting our experimental findings. Collectively, these studies allow us to propose a working model for RPE65-membrane binding, and to provide a novel role for cysteine palmitoylation.