Human cellular retinaldehyde-binding protein has secondary thermal 9-cis-retinal isomerase activity.
- Bolze CS Department of Chemistry and Biochemistry, and ‡Graduate School for Cellular and Biomedical Sciences, University of Bern , Freiestrasse 3, 3012 Bern, Switzerland.
- Helbling RE
- Owen RL
- Pearson AR
- Pompidor G
- Dworkowski F
- Fuchs MR
- Furrer J
- Golczak M
- Palczewski K
- Cascella M
- Stocker A
- 2013-12-17
Published in:
- Journal of the American Chemical Society. - 2014
Carrier Proteins
Chromatography, High Pressure Liquid
Crystallography, X-Ray
Diterpenes
Humans
Isomerases
Kinetics
Magnetic Resonance Spectroscopy
Models, Molecular
Quantum Theory
Retinaldehyde
Substrate Specificity
English
Cellular retinaldehyde-binding protein (CRALBP) chaperones 11-cis-retinal to convert opsin receptor molecules into photosensitive retinoid pigments of the eye. We report a thermal secondary isomerase activity of CRALBP when bound to 9-cis-retinal. UV/vis and (1)H NMR spectroscopy were used to characterize the product as 9,13-dicis-retinal. The X-ray structure of the CRALBP mutant R234W:9-cis-retinal complex at 1.9 Å resolution revealed a niche in the binding pocket for 9-cis-aldehyde different from that reported for 11-cis-retinal. Combined computational, kinetic, and structural data lead us to propose an isomerization mechanism catalyzed by a network of buried waters. Our findings highlight a specific role of water molecules in both CRALBP-assisted specificity toward 9-cis-retinal and its thermal isomerase activity yielding 9,13-dicis-retinal. Kinetic data from two point mutants of CRALBP support an essential role of Glu202 as the initial proton donor in this isomerization reaction.
- Language
-
- English
- Open access status
- green
- Identifiers
-
- DOI 10.1021/ja411366w
- PMID 24328211
- Persistent URL
- https://sonar.ch/global/documents/86551
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