A methyl group at C7 of 11-cis-retinal allows chromophore formation but affects rhodopsin activation.
The newly synthesized 11-cis-7-methylretinal can form an artificial visual pigment with kinetic and spectroscopic properties similar to the native pigment in the dark-state. However, its photobleaching behavior is altered, showing a Meta I-like photoproduct. This behavior reflects a steric constraint imposed by the 7-methyl group that affects the conformational change in the binding pocket as a result of retinal photoisomerization. Transducin activation is reduced, when compared to the native pigment with 11-cis-retinal. Molecular dynamics simulations suggest coupling of the C7 methyl group and the beta-ionone ring with Met207 in transmembrane helix 5 in agreement with recent experimental results.
Bosch
Laia
L
Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, 08222 Terrassa, Catalonia, Spain.
Cordomí
Arnau
A
Domínguez
Marta
M
Toledo
Darwin
D
Morillo
Margarita
M
Pérez
Juan J
JJ
Alvarez
Rosana
R
de Lera
Angel R
AR
Garriga
Pere
P
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003198:Computer Simulation; D003623:Dark Adaptation; D004224:Diterpenes; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D012172:Retinaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D012243:Rhodopsin / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D015293:Transducin / Q000378:metabolism*; D014785:Vision, Ocular / Q000502:physiology
C516946:7-methylretinal; C516945:8-methylretinal; D004224:Diterpenes; D012243:Rhodopsin; D019204:GTP-Binding Proteins; D015293:Transducin; D012172:Retinaldehyde