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Sci Adv. 2016 Aug 12;2(8):e1600920. doi: 10.1126/sciadv.1600920. eCollection 2016 Aug.

Structural photoactivation of a full-length bacterial phytochrome.

Author information

1
University of Gothenburg, 40530 Gothenburg, Sweden.
2
University of Jyväskylä, 40014 Jyväskylä, Finland.
3
University of Gothenburg, 40530 Gothenburg, Sweden.; University of Jyväskylä, 40014 Jyväskylä, Finland.
4
University of Chicago, Chicago, IL 60637, USA.
5
Tampere University of Technology, 33720 Tampere, Finland.
6
Paul Scherrer Institut, Villigen, 5232 Villigen PSI, Switzerland.
7
European Synchrotron Radiation Facility, 38000 Grenoble, France.

Abstract

Phytochromes are light sensor proteins found in plants, bacteria, and fungi. They function by converting a photon absorption event into a conformational signal that propagates from the chromophore through the entire protein. However, the structure of the photoactivated state and the conformational changes that lead to it are not known. We report time-resolved x-ray scattering of the full-length phytochrome from Deinococcus radiodurans on micro- and millisecond time scales. We identify a twist of the histidine kinase output domains with respect to the chromophore-binding domains as the dominant change between the photoactivated and resting states. The time-resolved data further show that the structural changes up to the microsecond time scales are small and localized in the chromophore-binding domains. The global structural change occurs within a few milliseconds, coinciding with the formation of the spectroscopic meta-Rc state. Our findings establish key elements of the signaling mechanism of full-length bacterial phytochromes.

PMID:
27536728
PMCID:
PMC4982709
DOI:
10.1126/sciadv.1600920
[Indexed for MEDLINE]
Free PMC Article

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