Dynamic Nuclear Polarization Provides New Insights into Chromophore Structure in Phytochrome Photoreceptors

Phytochromes are red/far‐red photochromic photoreceptors acting as master regulators of development in higher plants, thereby controlling transcription of about 20 % of their genes. Light‐induced isomerization of the bilin chromophore leads to large rearrangements in protein structure, whereby the r...

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Published in:Angewandte Chemie (International ed.) 2016-12, Vol.55 (52), p.16017-16020
Main Authors: Stöppler, Daniel, Song, Chen, van Rossum, Barth-Jan, Geiger, Michel-Andreas, Lang, Christina, Mroginski, Maria-Andrea, Jagtap, Anil Pandurang, Sigurdsson, Snorri Th, Matysik, Jörg, Hughes, Jon, Oschkinat, Hartmut
Format: Article
Language:English
Subjects:
chromophores
dynamic nuclear polarization
NMR spectroscopy
photochemistry
Photoreceptors
phytochromes
Signal to noise ratio
Spectrum analysis
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Summary:Phytochromes are red/far‐red photochromic photoreceptors acting as master regulators of development in higher plants, thereby controlling transcription of about 20 % of their genes. Light‐induced isomerization of the bilin chromophore leads to large rearrangements in protein structure, whereby the role of protonation dynamics and charge distribution is of particular interest. To help unravel the inherent mechanisms, we present two‐dimensional dynamic nuclear polarization (DNP) enhanced solid‐state magic‐angle spinning (MAS) NMR spectra of the functional sensory module of the cyanobacterial phytochrome Cph1. To this end, the pyrrole ring nitrogen signals were assigned unequivocally, enabling us to locate the positive charge of the phycocyanobilin (PCB) chromophore. To help analyze proton exchange pathways, the proximity of PCB ring nitrogen atoms and functionally relevant H2O molecules was also determined. Our study demonstrates the value of DNP in biological solid‐state MAS NMR spectroscopy. The phytochrome photocycle: The cyanobacterial phytochrome Cph1 regulates cellular processes through light. Dynamic nuclear polarization enhanced solid‐state magic‐angle spinning NMR spectroscopy was applied to illuminate the mechanism of phytochrome molecular action. The approach enables the assignment of the phycocyanobilin (PCB) chromophore resonances, which allowed localization of the positive charge in PCB.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201608119