| 1. |
- Bódizs, Szabolcs, et al.
(författare)
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Cryo-EM structures of a bathy phytochrome histidine kinase reveal a unique light-dependent activation mechanism
- 2024
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Ingår i: Structure. - 0969-2126 .- 1878-4186.
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are photoreceptor proteins in plants, fungi and bacteria. They can adopt two photochromic states with differential biochemical responses. The structural changes transducing the signal from the chromophore to the biochemical output modules are poorly understood due to challenges in capturing structures of the dynamic, full-length protein. Here, we present cryo-electron microscopy structures of the phytochrome from Pseudomonas aeruginosa (PaBphP) in its resting Pfr and photoactivated Pr state. The kinase-active Pr state has an asymmetric, dimeric structure, whereas the kinase-inactive Pfr state opens up. This behaviour is different from other known phytochromes and we explain it with the unusually short connection between the photosensory and output modules. Multiple sequence alignment of this region suggests evolutionary optimisation for different modes of signal transduction in sensor proteins. The results establish a new mechanism for light-sensing by phytochrome histidine kinases and provide input for the design of optogenetic phytochrome variants.
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| 2. |
- Konold, Patrick E., et al.
(författare)
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3D-printed sheet jet for stable megahertz liquid sample delivery at X-ray free-electron lasers
- 2023
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Ingår i: IUCrJ. - : International Union Of Crystallography. - 2052-2525. ; 10, s. 662-670
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Tidskriftsartikel (refereegranskat)abstract
- X-ray free-electron lasers (XFELs) can probe chemical and biological reactions as they unfold with unprecedented spatial and temporal resolution. A principal challenge in this pursuit involves the delivery of samples to the X-ray interaction point in such a way that produces data of the highest possible quality and with maximal efficiency. This is hampered by intrinsic constraints posed by the light source and operation within a beamline environment. For liquid samples, the solution typically involves some form of high-speed liquid jet, capable of keeping up with the rate of X-ray pulses. However, conventional jets are not ideal because of radiation-induced explosions of the jet, as well as their cylindrical geometry combined with the X-ray pointing instability of many beamlines which causes the interaction volume to differ for every pulse. This complicates data analysis and contributes to measurement errors. An alternative geometry is a liquid sheet jet which, with its constant thickness over large areas, eliminates the problems related to X-ray pointing. Since liquid sheets can be made very thin, the radiation-induced explosion is reduced, boosting their stability. These are especially attractive for experiments which benefit from small interaction volumes such as fluctuation X-ray scattering and several types of spectroscopy. Although their use has increased for soft X-ray applications in recent years, there has not yet been wide-scale adoption at XFELs. Here, gas-accelerated liquid sheet jet sample injection is demonstrated at the European XFEL SPB/SFX nano focus beamline. Its performance relative to a conventional liquid jet is evaluated and superior performance across several key factors has been found. This includes a thickness profile ranging from hundreds of nanometres to 60 nm, a fourfold increase in background stability and favorable radiation-induced explosion dynamics at high repetition rates up to 1.13 MHz. Its minute thickness also suggests that ultrafast single-particle solution scattering is a possibility.
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| 3. |
- Konold, Patrick E., et al.
(författare)
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Microsecond time-resolved X-ray scattering by utilizing MHz repetition rate at second-generation XFELs
- 2024
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Ingår i: NATURE METHODS. - : NATURE PORTFOLIO. - 1548-7091 .- 1548-7105.
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Tidskriftsartikel (refereegranskat)abstract
- Detecting microsecond structural perturbations in biomolecules has wide relevance in biology, chemistry and medicine. Here we show how MHz repetition rates at X-ray free-electron lasers can be used to produce microsecond time-series of protein scattering with exceptionally low noise levels of 0.001%. We demonstrate the approach by examining J alpha helix unfolding of a light-oxygen-voltage photosensory domain. This time-resolved acquisition strategy is easy to implement and widely applicable for direct observation of structural dynamics of many biochemical processes. The MHz repetition rates available at second-generation X-ray free-electron lasers enable the collection of microsecond time-resolved X-ray scattering data with exceptionally low noise, providing insights into protein structural dynamics.
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| 4. |
- Konold, Patrick, et al.
(författare)
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Microsecond time-resolved X-ray scattering by utilizing MHz repetition rate at second-generation XFELs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Detecting microsecond structural perturbations in biomolecules has wide relevance inbiology, chemistry, and medicine. Here, we show how MHz repetition rates at X-ray freeelectron lasers (XFELs) can be used to produce microsecond time-series of proteinscattering with exceptionally low noise levels of 0.001%. We demonstrate the approach byderiving new mechanistic insight into Jɑ helix unfolding of a Light-Oxygen-Voltage (LOV)photosensory domain. This time-resolved acquisition strategy is easy to implement andwidely applicable for direct observation of structural dynamics of many biochemicalprocesses.
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| 5. |
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| 6. |
- Westenhoff, Sebastian, 1978, et al.
(författare)
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Protein motions visualized by femtosecond time-resolved crystallography: The case of photosensory vs photosynthetic proteins
- 2022
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Ingår i: Current Opinion in Structural Biology. - : Elsevier BV. - 0959-440X .- 1879-033X. ; 77
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Tidskriftsartikel (refereegranskat)abstract
- Proteins are dynamic objects and undergo conformational changes when functioning. These changes range from inter -conversion between states in equilibrium to ultrafast and coherent structural motions within one perturbed state. Time -resolved serial femtosecond crystallography at free-electron X-ray lasers can unravel structural changes with atomic reso-lution and down to femtosecond time scales. In this review, we summarize recent advances on detecting structural changes for phytochrome photosensor proteins and a bacterial photosyn-thetic reaction center. In the phytochrome structural changes are extensive and involve major rearrangements of many amino acids and water molecules, accompanying the regulation of its biochemical activity, whereas in the photosynthetic reaction center protein the structural changes are smaller, more local-ized, and are optimized to facilitate electron transfer along the chromophores. The detected structural motions underpin the proteins' function, providing a showcase for the importance of detecting ultrafast protein structural dynamics.
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