Light-induced structural changes in a full-length cyanobacterial phytochrome probed by time- resolved X-ray scattering

Derren J. Heyes (1) , Samantha J. O. Hardman (1) , Martin N. Pedersen (2) , Joyce Woodhouse (3) , Eugenio de La Mora (3) , Michael Wulff (2) , Martin Weik (3) , Marco Cammarata (4) , Nigel S. Scrutton (1) , Giorgio Schirò (3)

1 University of Manchester [Manchester]
2 ESRF - European Synchrotron Radiation Facility
3 IBS - UMR 5075 - Institut de biologie structurale
4 IPR - Institut de Physique de Rennes

Phytochromes are photoreceptor proteins that transmit a light signal from a photosensory region to an output domain. Photoconversion involves protein conformational changes whose nature is not fully understood. Here, we use time-resolved X-ray scattering and optical spectroscopy to study the kinetics of structural changes in a full-length cyanobacterial phytochrome and in a truncated form with no output domain. X-ray and spectroscopic signals on the mu s/ms timescale are largely independent of the presence of the output domain. On longer time-scales, large differences between the full-length and truncated proteins indicate the timeframe during which the structural transition is transmitted from the photosensory region to the output domain and represent a large quaternary motion. The suggested independence of the photosensory-region dynamics on the mu s/ms timescale defines a time window in which the photoreaction can be characterized (e.g. for optogenetic design) independently of the nature of the engineered output domain.

Domains: Physics [physics]

Derren J. Heyes, Samantha J. O. Hardman, Martin N. Pedersen, Joyce Woodhouse, Eugenio de La Mora, et al.. Light-induced structural changes in a full-length cyanobacterial phytochrome probed by time- resolved X-ray scattering. Communications Biology, 2019, 2 (1), pp.1. ⟨10.1038/s42003-018-0242-0⟩. ⟨hal-02086213⟩