A Photoisomerizing Rhodopsin Mimic Observed at Atomic Resolution.
The members of the rhodopsin family of proteins are involved in many essential light-dependent processes in biology. Specific photoisomerization of the protein-bound retinylidene PSB at a specified wavelength range of light is at the heart of all of these systems. Nonetheless, it has been difficult to reproduce in an engineered system. We have developed rhodopsin mimics, using intracellular lipid binding protein family members as scaffolds, to study fundamental aspects of protein/chromophore interactions. Herein we describe a system that specifically isomerizes the retinylidene protonated Schiff base both thermally and photochemically. This isomerization has been characterized at atomic resolution by quantitatively interconverting the isomers in the crystal both thermally and photochemically. This event is accompanied by a large pKa change of the imine similar to the pKa changes observed in bacteriorhodopsin and visual opsins during isomerization.
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Meisam
M
Nosrati
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Tetyana
T
Berbasova
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Chrysoula
C
Vasileiou
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Babak
B
Borhan
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
James H
JH
Geiger
D040761:Biomimetic Materials / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D055668:Photochemical Processes; D011487:Protein Conformation; D015202:Protein Engineering; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism
D018168:Receptors, Retinoic Acid; C082927:retinoic acid binding protein I, cellular; C082928:retinoic acid binding protein II, cellular; D012243:Rhodopsin