Search results for "Deinococcus radiodurans"
showing 10 items of 19 documents
Light-induced structural changes in a monomeric bacteriophytochrome
2016
International audience; Phytochromes sense red light in plants and various microorganism. Light absorption causes structural changes within the protein, which alter its biochemical activity. Bacterial phytochromes are dimeric proteins, but the functional relevance of this arrangement remains unclear. Here, we use time-resolved X-ray scattering to reveal the solution structural change of a monomeric variant of the photosensory core module of the phytochrome from Deinococcus radiodurans. The data reveal two motions, a bend and a twist of the PHY domain with respect to the chromophore-binding domains. Infrared spectroscopy shows the refolding of the PHY tongue. We conclude that a monomer of th…
Chromophore-Protein Interplay During the Phytochrome Photocycle Revealed by Step-Scan FTIR Spectroscopy
2018
Phytochrome proteins regulate many photoresponses of plants and microorganisms. Light absorption causes isomerization of the biliverdin chromophore, which triggers a series of structural changes to activate the signaling domains of the protein. However, the structural changes are elusive, and therefore the molecular mechanism of signal transduction remains poorly understood. Here, we apply two-color step-scan infrared spectroscopy to the bacteriophytochrome from Deinococcus radiodurans. We show by recordings in H2O and D2O that the hydrogen bonds to the biliverdin D-ring carbonyl become disordered in the first intermediate (Lumi-R) forming a dynamic microenvironment, then completely detach …
On the (un)coupling of the chromophore, tongue interactions, and overall conformation in a bacterial phytochrome
2018
Phytochromes are photoreceptors in plants, fungi, and various microorganisms and cycle between metastable red light-absorbing (Pr) and far-red light-absorbing (Pfr) states. Their light responses are thought to follow a conserved structural mechanism that is triggered by isomerization of the chromophore. Downstream structural changes involve refolding of the so-called tongue extension of the phytochrome-specific GAF-related (PHY) domain of the photoreceptor. The tongue is connected to the chromophore by conserved DIP and PRXSF motifs and a conserved tyrosine, but the role of these residues in signal transduction is not clear. Here, we examine the tongue interactions and their interplay with …
Coordination of the biliverdin D-ring in bacteriophytochromes.
2018
Phytochrome proteins translate light into biochemical signals in plants, fungi and microorganisms. Light cues are absorbed by a bilin chromophore, leading to an isomerization and a rotation of the D-ring. This relays the signal to the protein matrix. A set of amino acids, which is conserved across the phytochrome superfamily, holds the chromophore in the binding pocket. However, the functional role of many of these amino acids is not yet understood. Here, we investigate the hydrogen bonding network which surrounds the D-ring of the chromophore in the resting (Pr) state. We use UV/vis spectroscopy, infrared absorption spectroscopy and X-ray crystallography to compare the photosensory domains…
Illuminating a Phytochrome Paradigm – a Light-Activated Phosphatase in Two-Component Signaling Uncovered
2020
ABSTRACTBacterial phytochrome photoreceptors usually belong to two-component signaling systems which transmit environmental stimuli to a response regulator through a histidine kinase domain. Phytochromes switch between red light-absorbing and far-red light-absorbing states. Despite exhibiting extensive structural responses during this transition, the model bacteriophytochrome fromDeinococcus radiodurans(DrBphP) lacks detectable kinase activity. Here, we resolve this long-standing conundrum by comparatively analyzing the interactions and output activities of DrBphP and a bacteriophytochrome fromAgrobacterium fabrum(AgP1). Whereas AgP1 acts as a conventional histidine kinase, we identify DrBp…
Deinococcus radiodurans' SRA-HNH domain containing protein Shp (Dr1533) is involved in faithful genome inheritance maintenance following DNA damage
2018
WOS:000452343100012; International audience; Background: Deinococcus radiodurans R1 (DR) survives conditions of extreme desiccation, irradiation and exposure to genotoxic chemicals, due to efficient DNA breaks repair, also through Mn2+ protection of DNA repair enzymes. Methods: Possible annotated domains of the DR1533 locus protein (Shp) were searched by bioinformatic analysis. The gene was cloned and expressed as fusion protein. Band-shift assays of Shp or the SRA and HNH domains were performed on oligonucleotides, genomic DNA from E. coif and DR. slip knock-out mutant was generated by homologous recombination with a kanamycin resistance cassette. Results: DR1533 contains an N-terminal SRA…
The primary structural photoresponse of phytochrome proteins captured by a femtosecond X-ray laser
2019
Phytochrome proteins control the growth, reproduction, and photosynthesis of plants, fungi, and bacteria. Light is detected by a bilin cofactor, but it remains elusive how this leads to activation of the protein through structural changes. We present serial femtosecond X-ray crystallographic data of the chromophore-binding domains of a bacterial phytochrome at delay times of 1 ps and 10 ps after photoexcitation. The data reveal a twist of the D-ring, which leads to partial detachment of the chromophore from the protein. Unexpectedly, the conserved so-called pyrrole water is photodissociated from the chromophore, concomitant with movement of the A-ring and a key signaling aspartate. The chan…
Light-induced Changes in the Dimerization Interface of Bacteriophytochromes
2015
Phytochromes are dimeric photoreceptor proteins that sense red light levels in plants, fungi, and bacteria. The proteins are structurally divided into a light-sensing photosensory module consisting of PAS, GAF, and PHY domains and a signaling output module, which in bacteriophytochromes typically is a histidine kinase (HK) domain. Existing structural data suggest that two dimerization interfaces exist between the GAF and HK domains, but their functional roles remain unclear. Using mutational, biochemical, and computational analyses of the Deinococcus radiodurans phytochrome, we demonstrate that two dimerization interfaces between sister GAF and HK domains stabilize the dimer with approximat…
Exploring the Specificity of Rationally Designed Peptides Reconstituted from the Cell-Free Extract of Deinococcus radiodurans toward Mn(II) and Cu(II)
2020
A series of five rationally designed decapeptides [DEHGTAVMLK (DP1), THMVLAKGED (DP2), GTAVMLKDEH (Term-DEH), TMVLDEHAKG (Mid-DEH), and DEHGGGGDEH (Bis-DEH)] have been studied for their interactions with Cu(II) and Mn(II) ions. The peptides, constructed including the most prevalent amino acid content found in the cell-free extract of Deinococcus radiodurans (DR), play a fundamental role in the antioxidant mechanism related to its exceptional radioresistance. Mn(II) ions, in complex with these peptides, are found to be an essential ingredient for the DR protection kit. In this work, a detailed characterization of Cu(II) systems was included, because Cu(II)–peptide complexes have also shown r…
Structural photoactivation of a full-length bacterial phytochrome
2016
Time-resolved x-ray solution scattering reveals the conformational signaling mechanism of a bacterial phytochrome.