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

Phototropin2 (phot2) is a blue-light (BL) receptor protein that regulates the BL-dependent activities of plants for efficient photosynthesis. Phot2 is composed of two light-oxygen-voltage sensing domains (LOV1 and LOV2) to absorb BL, and a kinase domain. Photo-activated LOV domains, especially LOV2, play a major role in photo-dependent increase in the phosphorylation activity of the kinase domain. The atomic details of the overall structure of phot2 and the intramolecular mechanism to convert BL energy to a phosphorylation signal remain unknown. We performed structural studies on the LOV fragments LOV1, LOV2, LOV2-linker, and LOV2-kinase, and full-length phot2, using small-angle X-ray scattering (SAXS). The aim of the study was to understand structural changes under BL irradiation and discuss the molecular mechanism that enhance the phosphorylation activity under BL. SAXS is a suitable technique for visualizing molecular structures of proteins in solution at low resolution and is advantageous for monitoring their structural changes in the presence of external physical and/or chemical stimuli. Structural parameters and molecular models of the recombinant specimens were obtained from SAXS profiles in the dark, under BL irradiation, and after dark reversion. LOV1, LOV2, and LOV2-linker fragments displayed minimal structural changes. However, BL-induced rearrangements of functional domains were noted for LOV2-kinase and full-length phot2. Based on the molecular model together with the absorption measurements and biochemical assays, we discuss the intramolecular interactions and domain motions necessary for BL-enhanced phosphorylation activity of phot2.

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Photocage-initiated time-resolved solution X-ray scattering investigation of protein dimerization

IUCrJ ◽

10.1107/s2052252518012149 ◽

2018 ◽

Vol 5 (6) ◽

pp. 667-672 ◽

Cited By ~ 6

Author(s):

Inokentijs Josts ◽

Stephan Niebling ◽

Yunyun Gao ◽

Matteo Levantino ◽

Henning Tidow ◽

...

Keyword(s):

Small Molecule ◽

Conformational Changes ◽

Structural Changes ◽

Time Resolved ◽

Protein Dimerization ◽

X Ray ◽

Single Turnover ◽

X Ray Scattering ◽

Photoactivatable Proteins ◽

Ray Scattering

This work demonstrates a new method for investigating time-resolved structural changes in protein conformation and oligomerization via photocage-initiated time-resolved X-ray solution scattering by observing the ATP-driven dimerization of the MsbA nucleotide-binding domain. Photocaged small molecules allow the observation of single-turnover reactions of non-naturally photoactivatable proteins. The kinetics of the reaction can be derived from changes in X-ray scattering associated with ATP-binding and subsequent dimerization. This method can be expanded to any small-molecule-driven protein reaction with conformational changes traceable by X-ray scattering where the small molecule can be photocaged.

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Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments

IUCrJ ◽

10.1107/s2052252514019198 ◽

2014 ◽

Vol 1 (6) ◽

pp. 478-491 ◽

Cited By ~ 15

Author(s):

Wim Bras ◽

Satoshi Koizumi ◽

Nicholas J Terrill

Keyword(s):

Simultaneous Measurement ◽

Structural Changes ◽

Driving Forces ◽

X Rays ◽

Environment Design ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Complementary Techniques ◽

Ray Scattering

Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques,viaeither simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

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Anisotropy enhanced X-ray scattering from solvated transition metal complexes

Journal of Synchrotron Radiation ◽

10.1107/s1600577517016964 ◽

2018 ◽

Vol 25 (2) ◽

pp. 306-315 ◽

Cited By ~ 17

Author(s):

Elisa Biasin ◽

Tim B. van Driel ◽

Gianluca Levi ◽

Mads G. Laursen ◽

Asmus O. Dohn ◽

...

Keyword(s):

Structural Changes ◽

Platinum Complex ◽

Anisotropic Scattering ◽

Isotropic Scattering ◽

Time Resolved ◽

Instrument Response Function ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

Time-resolved X-ray scattering patterns from photoexcited molecules in solution are in many cases anisotropic at the ultrafast time scales accessible at X-ray free-electron lasers (XFELs). This anisotropy arises from the interaction of a linearly polarized UV–Vis pump laser pulse with the sample, which induces anisotropic structural changes that can be captured by femtosecond X-ray pulses. In this work, a method for quantitative analysis of the anisotropic scattering signal arising from an ensemble of molecules is described, and it is demonstrated how its use can enhance the structural sensitivity of the time-resolved X-ray scattering experiment. This method is applied on time-resolved X-ray scattering patterns measured upon photoexcitation of a solvated di-platinum complex at an XFEL, and the key parameters involved are explored. It is shown that a combined analysis of the anisotropic and isotropic difference scattering signals in this experiment allows a more precise determination of the main photoinduced structural change in the solute,i.e.the change in Pt—Pt bond length, and yields more information on the excitation channels than the analysis of the isotropic scattering only. Finally, it is discussed how the anisotropic transient response of the solvent can enable the determination of key experimental parameters such as the instrument response function.

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Probing in cell protein structural changes with time-resolved X-ray scattering

Soft Matter ◽

10.1039/c2sm25676b ◽

2012 ◽

Vol 8 (24) ◽

pp. 6434 ◽

Cited By ~ 10

Author(s):

Alessandro Spilotros ◽

Matteo Levantino ◽

Giorgio Schirò ◽

Marco Cammarata ◽

Michael Wulff ◽

...

Keyword(s):

Structural Changes ◽

Cell Protein ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

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Time-Resolved Structural Dynamics of Organic Mixed Ionic Electronic Conductors

10.26434/chemrxiv.12312299 ◽

2020 ◽

Author(s):

Bryan D. Paulsen ◽

Ruiheng Wu ◽

Christopher Takacs ◽

Hans-Georg Steinrück ◽

Joseph Strzalka ◽

...

Keyword(s):

Structural Changes ◽

Polymer System ◽

Mixed Conductor ◽

Electronic Charge ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Mixed Ionic Electronic Conductors ◽

Electronic Conductors ◽

Ray Scattering

<div> <div> <div> <p>The structure and packing of organic mixed ionic-electronic conductors have an outsized effect on transport properties. In operating devices this structure is not fixed but is responsive to changes in electrochemical potential, ion intercalation, and solvent swelling. Towards this end, the dynamic structure of a model organic mixed conductor is characterized using multimodal time-resolved operando techniques. Time-resolved operando X-ray scattering reveals asymmetric rates of structural change during doping and dedoping that do not directly depend on potential or charging dynamics. Time-resolved spectroscopy establishes a link between structural transients and the complex dynamics of electronic charge carrier subpopulations, in particular the polaron-bipolaron equilibrium. These findings provide insight into the factors limiting the response time of organic mixed conductor based devices, and present the first real-time observation of the structural changes during doping and dedoping of a conjugated polymer system via X-ray scattering. </p> </div> </div> </div>

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Time-Resolved Structural Dynamics of Organic Mixed Ionic Electronic Conductors

10.26434/chemrxiv.12312299.v1 ◽

2020 ◽

Author(s):

Bryan D. Paulsen ◽

Ruiheng Wu ◽

Christopher Takacs ◽

Hans-Georg Steinrück ◽

Joseph Strzalka ◽

...

Keyword(s):

Structural Changes ◽

Polymer System ◽

Mixed Conductor ◽

Electronic Charge ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Mixed Ionic Electronic Conductors ◽

Electronic Conductors ◽

Ray Scattering

<div> <div> <div> <p>The structure and packing of organic mixed ionic-electronic conductors have an outsized effect on transport properties. In operating devices this structure is not fixed but is responsive to changes in electrochemical potential, ion intercalation, and solvent swelling. Towards this end, the dynamic structure of a model organic mixed conductor is characterized using multimodal time-resolved operando techniques. Time-resolved operando X-ray scattering reveals asymmetric rates of structural change during doping and dedoping that do not directly depend on potential or charging dynamics. Time-resolved spectroscopy establishes a link between structural transients and the complex dynamics of electronic charge carrier subpopulations, in particular the polaron-bipolaron equilibrium. These findings provide insight into the factors limiting the response time of organic mixed conductor based devices, and present the first real-time observation of the structural changes during doping and dedoping of a conjugated polymer system via X-ray scattering. </p> </div> </div> </div>

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