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Photoreversible interconversion of a phytochrome photosensory module in the crystalline state

DOI: 10.1073/pnas.1912041116 DOI Help

Authors: E. Sethe Burgie (Washington University in St. Louis) , Jonathan A. Clinger (Rice University) , Mitchell D. Miller (Rice University) , Aaron S. Brewster (Lawrence Berkeley National Laboratory) , Pierre Aller (Diamond Light Source) , Agata Butryn (Diamond Light Source) , Franklin D. Fuller (Linac Coherent Light Source, SLAC National Accelerator Laboratory) , Sheraz Gul (Lawrence Berkeley National Laboratory) , Iris D. Young (Lawrence Berkeley National Laboratory) , Cindy C. Pham (Lawrence Berkeley National Laboratory) , In-sik Kim (Lawrence Berkeley National Laboratory) , Asmit Bhowmick (Lawrence Berkeley National Laboratory) , Lee J. O’riordan (Lawrence Berkeley National Laboratory) , Kyle D. Sutherlin (Lawrence Berkeley National Laboratory) , Joshua V. Heinemann (Lawrence Berkeley National Laboratory) , Alexander Batyuk (Linac Coherent Light Source, SLAC National Accelerator Laboratory) , Roberto Alonso-mori (Linac Coherent Light Source, SLAC National Accelerator Laboratory) , Mark S. Hunter (Linac Coherent Light Source, SLAC National Accelerator Laboratory) , Jason E. Koglin (Linac Coherent Light Source, SLAC National Accelerator Laboratory) , Junko Yano (Lawrence Berkeley National Laboratory) , Vittal K. Yachandra (Lawrence Berkeley National Laboratory) , Nicholas K. Sauter (Lawrence Berkeley National Laboratory) , Aina E. Cohen (Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory) , Jan Kern (Lawrence Berkeley National Laboratory) , Allen M. Orville (Diamond Light Source; Research Complex at Harwell) , George N. Phillips (Rice University) , Richard D. Vierstra (Washington University in St. Louis)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Proceedings Of The National Academy Of Sciences , VOL 37

State: Published (Approved)
Published: December 2019
Diamond Proposal Number(s): 19458

Open Access Open Access

Abstract: A major barrier to defining the structural intermediates that arise during the reversible photointerconversion of phytochromes between their biologically inactive and active states has been the lack of crystals that faithfully undergo this transition within the crystal lattice. Here, we describe a crystalline form of the cyclic GMP phosphodiesterases/adenylyl cyclase/FhlA (GAF) domain from the cyanobacteriochrome PixJ in Thermosynechococcus elongatus assembled with phycocyanobilin that permits reversible photoconversion between the blue light-absorbing Pb and green light-absorbing Pg states, as well as thermal reversion of Pg back to Pb. The X-ray crystallographic structure of Pb matches previous models, including autocatalytic conversion of phycocyanobilin to phycoviolobilin upon binding and its tandem thioether linkage to the GAF domain. Cryocrystallography at 150 K, which compared diffraction data from a single crystal as Pb or after irradiation with blue light, detected photoconversion product(s) based on Fobs − Fobs difference maps that were consistent with rotation of the bonds connecting pyrrole rings C and D. Further spectroscopic analyses showed that phycoviolobilin is susceptible to X-ray radiation damage, especially as Pg, during single-crystal X-ray diffraction analyses, which could complicate fine mapping of the various intermediate states. Fortunately, we found that PixJ crystals are amenable to serial femtosecond crystallography (SFX) analyses using X-ray free-electron lasers (XFELs). As proof of principle, we solved by room temperature SFX the GAF domain structure of Pb to 1.55-Å resolution, which was strongly congruent with synchrotron-based models. Analysis of these crystals by SFX should now enable structural characterization of the early events that drive phytochrome photoconversion.

Journal Keywords: phytochrome; photoreceptor; X-ray crystallography

Subject Areas: Biology and Bio-materials

Instruments: I24-Microfocus Macromolecular Crystallography

Other Facilities: Advanced Photon Source (APS)