27 research outputs found
The room temperature crystal structure of a bacterial phytochrome determined by serial femtosecond crystallography
Photosensing and Thermosensing by Phytochrome B Require Both Proximal and Distal Allosteric Features within the Dimeric Photoreceptor
Mapping light-driven conformational changes within the photosensory module of plant phytochrome B
Basic Phytochrome B Calculations
Mathematical models are important tools in helping us to understand complex biological systems. Models of phytochrome-regulated systems in Arabidopsis thaliana have shown the importance of dimerization, nuclear transport, and thermal/dark reversion in mediating phytochrome activity and plant development. Here we go through the steps required to calculate the steady-state amounts of phytochrome subspecies relative to the total phytochrome molecule population. Starting from a simplified two-state system we expand and apply the technique to the extended phytochrome dimer model. Additionally, we provide a Python package that can automatically calculate the proportion of phytochrome B in a particular state given specific experimental conditions.</p
Light-induced structural changes in a full-length cyanobacterial phytochrome probed by time-resolved X-ray scattering
Signal amplification and transduction in phytochrome photosensors
[Introduction] Page
2
of
20
Sensory proteins must relay structural signals from the sensory site over
large distances to regulatory output domains.
Phytochromes are a major
family of red-light sensing kinases that
control diverse cell
ular functions in
plants, bacteria, and fungi.
1-9
Bacterial phytochro
mes consist of a
photosensory core and a C-te
rminal regulatory domain.
10,11
Structures of
photosensory cores are reported in the resting state
12-18
and conformational
responses to light activat
ion have been proposed
in the vicinity of the
chromophore.
19-23
However, the structure of
the signalling state and the
mechanism of downstream signal re
lay through the photosensory core
remain elusive. Here, we report crystal
and solution structures of the resting
and active states of the photosensory core of the bacteriophytochrome from
Deinococcus radiodurans
. The structures reveal an
open and closed form of
the dimeric protein for the signalling an
d resting state, respectively. This
nanometre scale rearrangement is
controlled by refolding of an
evolutionarily conserved “tongue”
, which is in contact with the
chromophore.
The findings reveal an unus
ual mechanism where atomic
scale conformational ch
anges around the chromopho
re are first amplified
into an Ångström scale distance change
in the tongue, and
further grow into
a nanometre scale conformational sign
al. The structural
mechanism is a
blueprint for understanding how the sensor
proteins connect to the cellular
signalling network.peerReviewe