Search results for "Deinococcus radiodurans"
showing 9 items of 19 documents
Site-by-site tracking of signal transduction in an azidophenylalanine-labeled bacteriophytochrome with step-scan FTIR spectroscopy
2021
Signal propagation in photosensory proteins is a complex and multidimensional event. Unraveling such mechanisms site-specifically in real time is an eligible but a challenging goal. Here, we elucidate the site-specific events in a red-light sensing phytochrome using the unnatural amino acid azidophenylalanine, vibrationally distinguishable from all other protein signals. In canonical phytochromes, signal transduction starts with isomerization of an excited bilin chromophore, initiating a multitude of processes in the photosensory unit of the protein, which eventually control the biochemical activity of the output domain, nanometers away from the chromophore. By implementing the label in pri…
Signal amplification and transduction in phytochrome photosensors
2014
[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 e…
Transient IR spectroscopy identifies key interactions and unravels new intermediates in the photocycle of a bacterial phytochrome.
2020
Phytochromes are photosensory proteins in plants, fungi, and bacteria, which detect red- and far-red light. They undergo a transition between the resting (Pr) and photoactivated (Pfr) states. In bacterial phytochromes, the Pr-to-Pfr transition is facilitated by two intermediate states, called Lumi-R and Meta-R. The molecular structures of the protein in these states are not known and the molecular mechanism of photoconversion is not understood. Here, we apply transient infrared absorption spectroscopy to study the photocycle of the wild-type and Y263F mutant of the phytochrome from Deinococcus radiodurans (DrBphP) from nanoto milliseconds. We identify two sequentially forming Lumi-R states …
Modulation of Structural Heterogeneity Controls Phytochrome Photoswitching
2019
Phytochromes sense red/far-red light and control many biological processes in plants, fungi, and bacteria. Although crystal structures of dark and light adapted states have been determined, the molecular mechanisms underlying photoactivation remains elusive. Here we demonstrate that the conserved tongue region of the PHY domain of a 57kDa photosensory module of Deinococcus radiodurans phytochrome, changes from a structurally heterogeneous dark state to an ordered light activated state. The results were obtained in solution by utilizing a laser-triggered activation approach detected on the atomic level with high-resolution protein NMR spectroscopy. The data suggest that photosignaling of phy…
Fluorescence Properties of the Chromophore-Binding Domain of Bacteriophytochrome from Deinococcus radiodurans
2013
Fluorescent proteins are versatile tools for molecular imaging. In this study, we report a detailed analysis of the absorption and fluorescence properties of the chromophore-binding domain from Deinococcus radiodurans and its D207H mutant. Using single photon counting and transient absorption techniques, the average excited state lifetime of both studied systems was about 370 ps. The D207H mutation slightly changed the excited state decay profile but did not have a considerable effect on the average decay time of the system or the shape of the absorption and emission spectra of the biliverdin chromophore. We confirmed that the fluorescence properties of both samples are very similar in vivo…
Connection between Absorption Properties and Conformational Changes in Deinococcus radiodurans Phytochrome
2014
Phytochromes consist of several protein domains and a linear tetrapyrrole molecule, which interact as a red-light-sensing system. In this study, size-exclusion chromatography and light-scattering techniques are combined with UV-vis spectroscopy to investigate light-induced changes in dimeric Deinococcus radiodurans bacterial phytochrome (DrBphP) and its subdomains. The photosensory unit (DrCBD-PHY) shows an unusually stable Pfr state with minimal dark reversion, whereas the histidine kinase (HK) domain facilitates dark reversion to the resting state. Size-exclusion chromatography reveals that all phytochrome fragments remain as dimers in the illuminated state and dark state. Still, the elut…
ERA-experiment “space biochemistry”
1995
Abstract The general goal of the experiment was to study the response of anhydrobiotic (metabolically dormant) microorganisms (spores of Bacillus subtilis, cells of Deinococcus radiodurans, conidia of Aspergillus species) and cellular constituents (plasmid DNA, proteins, purple membranes, amino acids, urea) to the extremely dehydrating conditions of open space, in some cases in combination with irradiation by solar UV-light. Methods of investigation included viability tests, analysis of DNA damages (strand breaks, DNA-protein cross-links) and analysis of chemical effects by spectroscopic, electrophoretic and chromatographic methods. The decrease in viability of the microorganisms was as exp…
Removal of Chromophore-proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor
2015
Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in…
Photoinduced changes in phytochromes studied by means of low temperature UV-Vis spectroscopy
2018
Phytochromes are a major family of red-light-sensing kinases that control diverse cellular functions in plants, bacteria and fungi. These proteins must relay structural signals from the sensory site over large distances to regulatory output domains. To accomplish this function, they undergo rather large structural changes from one state to another. The general aim of this work was to study these structural changes and possible protonation states of the photosensory core of the bacteriophytochrome from Deinococcus radiodurans in the intermediate states of the photoreaction, which became possible to observe under low temperatures. Moreover, it was interesting to investigate the role Serine272…