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Highly conserved tyrosine stabilizes the active state of rhodopsin
- Source :
- Proceedings of the National Academy of Sciences of the United States of America. 107(46)
- Publication Year :
- 2010
-
Abstract
- Light-induced isomerization of the 11- cis- retinal chromophore in the visual pigment rhodopsin triggers displacement of the second extracellular loop (EL2) and motion of transmembrane helices H5, H6, and H7 leading to the active intermediate metarhodopsin II (Meta II). We describe solid-state NMR measurements of rhodopsin and Meta II that target the molecular contacts in the region of the ionic lock involving these three helices. We show that a contact between Arg135 3.50 and Met257 6.40 forms in Meta II, consistent with the outward rotation of H6 and breaking of the dark-state Glu134 3.49 -Arg135 3.50 -Glu247 6.30 ionic lock. We also show that Tyr223 5.58 and Tyr306 7.53 form molecular contacts with Met257 6.40 . Together these results reveal that the crystal structure of opsin in the region of the ionic lock reflects the active state of the receptor. We further demonstrate that Tyr223 5.58 and Ala132 3.47 in Meta II stabilize helix H5 in an active orientation. Mutation of Tyr223 5.58 to phenylalanine or mutation of Ala132 3.47 to leucine decreases the lifetime of the Meta II intermediate. Furthermore, the Y223F mutation is coupled to structural changes in EL2. In contrast, mutation of Tyr306 7.53 to phenylalanine shows only a moderate influence on the Meta II lifetime and is not coupled to EL2.
- Subjects :
- Opsin
Rhodopsin
Magnetic Resonance Spectroscopy
Stereochemistry
Protein Conformation
education
Biology
Crystallography, X-Ray
Protein Structure, Secondary
Structure-Activity Relationship
Protein structure
Animals
Humans
Conserved Sequence
Multidisciplinary
Alanine
Protein Stability
Nuclear magnetic resonance spectroscopy
Chromophore
Biological Sciences
META II
Transmembrane domain
HEK293 Cells
Amino Acid Substitution
Helix
Mutation
biology.protein
Tyrosine
Cattle
Mutant Proteins
Ion Channel Gating
Signal Transduction
Subjects
Details
- ISSN :
- 10916490
- Volume :
- 107
- Issue :
- 46
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Accession number :
- edsair.doi.dedup.....93e00b6ea2b26f94cb89d9e6e3cf2426