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Two ground state isoforms and a chromophore D-ring photoflip triggering extensive intramolecular changes in a canonical phytochrome.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2011 Mar 08; Vol. 108 (10), pp. 3842-7. Date of Electronic Publication: 2011 Feb 15. - Publication Year :
- 2011
-
Abstract
- Phytochrome photoreceptors mediate light responses in plants and in many microorganisms. Here we report studies using (1)H-(13)C magic-angle spinning NMR spectroscopy of the sensor module of cyanobacterial phytochrome Cph1. Two isoforms of the red-light absorbing Pr ground state are identified. Conclusive evidence that photoisomerization occurs at the C15-methine bridge leading to a β-facial disposition of the ring D is presented. In the far-red-light absorbing Pfr state, strong hydrogen-bonding interactions of the D-ring carbonyl group to Tyr-263 and of N24 to Asp-207 hold the chromophore in a tensed conformation. Signaling is triggered when Asp-207 is released from its salt bridge to Arg-472, probably inducing conformational changes in the tongue region. A second signal route is initiated by partner swapping of the B-ring propionate between Arg-254 and Arg-222.
Details
- Language :
- English
- ISSN :
- 1091-6490
- Volume :
- 108
- Issue :
- 10
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 21325055
- Full Text :
- https://doi.org/10.1073/pnas.1013377108