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Light-induced chromophore activity and signal transduction in phytochromes observed by 13C and 15N magic-angle spinning NMR.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2008 Oct 07; Vol. 105 (40), pp. 15229-34. Date of Electronic Publication: 2008 Oct 01. - Publication Year :
- 2008
-
Abstract
- Both thermally stable states of phytochrome, Pr and Pfr, have been studied by (13)C and (15)N cross-polarization (CP) magic-angle spinning (MAS) NMR using cyanobacterial (Cph1) and plant (phyA) phytochrome sensory modules containing uniformly (13)C- and (15)N-labeled bilin chromophores. Two-dimensional homo- and heteronuclear experiments allowed most of the (13)C chemical shifts to be assigned in both states. Chemical shift differences reflect changes of the electronic structure of the cofactor at the atomic level as well as its interactions with the chromophore-binding pocket. The chromophore in cyanobacterial and plant phytochromes shows very similar features in the respective Pr and Pfr states. The data are interpreted in terms of a strengthened hydrogen bond at the ring D carbonyl. The red shift in the Pfr state is explained by the increasing length of the conjugation network beyond ring C including the entire ring D. Enhanced conjugation within the pi-system stabilizes the more tensed chromophore in the Pfr state. Concomitant changes at the ring C propionate carboxylate and the ring D carbonyl are explained by a loss of hydrogen bonding to Cph1-His-290 and transmittance of conformational changes to the ring C propionate via a water network. These and other conformational changes may lead to modified surface interactions, e.g., along the tongue region contacting the bilin chromophore.
- Subjects :
- Bacterial Proteins chemistry
Bacterial Proteins metabolism
Bile Pigments chemistry
Carbon Isotopes chemistry
Light
Magnetic Resonance Spectroscopy
Models, Molecular
Nitrogen Isotopes chemistry
Photoreceptors, Microbial
Phycobilins chemistry
Phytochrome metabolism
Protein Conformation
Protein Kinases chemistry
Protein Kinases metabolism
Signal Transduction
Phytochrome chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1091-6490
- Volume :
- 105
- Issue :
- 40
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 18832155
- Full Text :
- https://doi.org/10.1073/pnas.0805696105