Structural and Functional Consequences of the Weak Binding of Chlorin e6 to Bovine Rhodopsin
Autor: | Mordechai Sheves, Kalyan C. Tirupula, Naveena Yanamala, Yi Lei Tan, James Mitchell, Judith Klein-Seetharaman, Fernanda Balem, Eric E. Gardner, Daniel Nietlispach |
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Rok vydání: | 2018 |
Předmět: |
0301 basic medicine
Rhodopsin Allosteric modulator Porphyrins genetic structures Light Protein Conformation 02 engineering and technology Biochemistry Retina Absorbance 03 medical and health sciences Protein structure Allosteric Regulation Animals Amino Acid Sequence Physical and Theoretical Chemistry Binding site Nuclear Magnetic Resonance Biomolecular biology Chlorophyllides Chemistry General Medicine Nuclear magnetic resonance spectroscopy 021001 nanoscience & nanotechnology Fluorescence 030104 developmental biology Spectrometry Fluorescence biology.protein Biophysics Proton NMR Cattle sense organs 0210 nano-technology Protein Binding |
Zdroj: | Photochemistry and photobiology. 95(3) |
ISSN: | 1751-1097 |
Popis: | The chlorophyll-derivative chlorin e6 (Ce6) identified in the retinas of deep-sea ocean fish is proposed to play a functional role in red bioluminescence detection. Fluorescence and 1 H NMR spectroscopy studies with the bovine dim-light photoreceptor, rhodopsin, indicate that Ce6 weakly binds to it with μm affinity. Absorbance spectra prove that red light sensitivity enhancement is not brought about by a shift in the absorbance maximum of rhodopsin. 19 F NMR experiments with samples where 19 F labels are either placed at the cytoplasmic binding site or incorporated as fluorinated retinal indicate that the cytoplasmic domain is highly perturbed by binding, while little to no changes are detected near the retinal. Binding of Ce6 also inhibits G-protein activation. Chemical shift changes in 1 H-15 N NMR spectroscopy of 15 N-Trp labeled bovine rhodopsin reveal that Ce6 binding perturbs the entire structure. These results provide experimental evidence that Ce6 is an allosteric modulator of rhodopsin. |
Databáze: | OpenAIRE |
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