Abstract
The red/far-red-sensing biological photoreceptor phytochrome is a paradigmatic two-state signaling system. The two thermally stable states are interconverted via a photoreaction of the covalently bound tetrapyrrole chromophore. Applying recently developed solid-state nuclear magnetic resonance, we study both the chromophore and its protein pocket in the Pr (red-absorbing) and Pfr (far-red-absorbing) states. The observations show that the phototransformation combines local chemical reactions with a mesoscopic transition of order. Both the chromophore and its binding pocket are quasi-liquid and disordered in Pr, yet quasi-solid and ordered in Pfr. Possible biochemical implications are discussed.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / chemistry
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Binding Sites
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Biocatalysis
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Hydrogen Bonding
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Models, Molecular
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Molecular Conformation
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Nuclear Magnetic Resonance, Biomolecular / methods
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Peptide Fragments / chemistry
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Photochemical Processes
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Photoreceptors, Microbial
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Photoreceptors, Plant / chemistry*
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Phycobilins / chemistry
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Phycocyanin / chemistry
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Phytochrome / chemistry*
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Phytochrome A / chemistry
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Phytochrome B / chemistry
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Protein Kinases / chemistry
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Signal Transduction
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Tetrapyrroles / chemistry
Substances
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Bacterial Proteins
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Peptide Fragments
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Photoreceptors, Microbial
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Photoreceptors, Plant
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Phycobilins
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Phytochrome A
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Tetrapyrroles
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Phycocyanin
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Phytochrome
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Phytochrome B
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phycocyanobilin
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Protein Kinases
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Cph1 phytochrome protein, bacteria