scholarly journals How the dual PDZ domain from Postsynaptic density protein 95 clusters ion channels and receptors

2019 ◽  
Author(s):  
Nazahiyah Ahmad Rodzli ◽  
Michael Lockhart-Cairns ◽  
Colin W. Levy ◽  
John Chipperfield ◽  
Louise Bird ◽  
...  
Keyword(s):  
Signal Transmission ◽  
Pdz Domain ◽  
Postsynaptic Density ◽  
Excitable Cells ◽  
Detailed Understanding ◽  
X Ray ◽  
X Ray Scattering ◽  
Dual Domain ◽  
Zona Occludens ◽  
Partner Proteins

AbstractPSD-95 is a member of Membrane Associated Guanylate Kinase class of proteins which form scaffolding interactions with partner proteins including ion and receptor channels. PSD-95 is directly implicated in modulating the electrical responses of excitable cells. The first two PSD-95/Disks Large/Zona Occludens domains of PSD-95 have been shown to be the key component in the formation of channel clusters. We report crystal structures of the dual domain in both in apo and ligand-bound form; thermodynamic analysis of ligand association and Small Angle X-ray Scattering of the dual domain in the absence and presence of ligands. These experiments reveal that the ligated double domain forms a scaffold in the complete sense of the word. The concentration of the components in this study is comparable to those found in compartments of excitable cells such as the postsynaptic density and juxta-paranodes of Ranvier. The properties of the dual domain explain the basis of the scaffolding function of PSD-95, and provide a more detailed understanding of the integration of key components of neuronal specializations involved in nervous signal transmission.

scholarly journals Nanostructure-specific X-ray tomography reveals myelin levels, integrity and axon orientations in mouse and human nervous tissue

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marios Georgiadis ◽  
Aileen Schroeter ◽  
Zirui Gao ◽  
Manuel Guizar-Sicairos ◽  
Marianne Liebi ◽  
...  
Keyword(s):  
Mouse Brain ◽  
Nervous Tissue ◽  
Signal Transmission ◽  
X Ray ◽  
Tensor Tomography ◽  
Quantitative Studies ◽  
X Ray Scattering ◽  
Imaging Approach ◽  
Non Destructive ◽  
Mri Measurements

AbstractMyelin insulates neuronal axons and enables fast signal transmission, constituting a key component of brain development, aging and disease. Yet, myelin-specific imaging of macroscopic samples remains a challenge. Here, we exploit myelin’s nanostructural periodicity, and use small-angle X-ray scattering tensor tomography (SAXS-TT) to simultaneously quantify myelin levels, nanostructural integrity and axon orientations in nervous tissue. Proof-of-principle is demonstrated in whole mouse brain, mouse spinal cord and human white and gray matter samples. Outcomes are validated by 2D/3D histology and compared to MRI measurements sensitive to myelin and axon orientations. Specificity to nanostructure is exemplified by concomitantly imaging different myelin types with distinct periodicities. Finally, we illustrate the method’s sensitivity towards myelin-related diseases by quantifying myelin alterations in dysmyelinated mouse brain. This non-destructive, stain-free molecular imaging approach enables quantitative studies of myelination within and across samples during development, aging, disease and treatment, and is applicable to other ordered biomolecules or nanostructures.

scholarly journals Concatenation of 14-3-3 with partner phosphoproteins as a tool to study their interaction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kristina V. Tugaeva ◽  
Daria I. Kalacheva ◽  
Richard B. Cooley ◽  
Sergei V. Strelkov ◽  
Nikolai N. Sluchanko
Keyword(s):  
Small Molecules ◽  
Limited Proteolysis ◽  
Scanning Calorimetry ◽  
Saxs Data ◽  
X Ray ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
X Ray Scattering ◽  
The Stability ◽  
Partner Proteins

Abstract Regulatory 14-3-3 proteins interact with a plethora of phosphorylated partner proteins, however 14-3-3 complexes feature intrinsically disordered regions and often a transient type of interactions making structural studies difficult. Here we engineer and examine a chimera of human 14-3-3 tethered to a nearly complete partner HSPB6 which is phosphorylated by protein kinase A (PKA). HSPB6 includes a long disordered N-terminal domain (NTD), a phosphorylation motif around Ser16, and a core α-crystallin domain (ACD) responsible for dimerisation. The chosen design enables an unstrained binding of pSer16 in each 1433 subunit and secures the correct 2:2 stoichiometry. Differential scanning calorimetry, limited proteolysis and small-angle X-ray scattering (SAXS) support the proper folding of both the 14-3-3 and ACD dimers within the chimera, and indicate that the chimera retains the overall architecture of the native complex of 14-3-3 and phosphorylated HSPB6 that has recently been resolved using crystallography. At the same time, the SAXS data highlight the weakness of the secondary interface between the ACD dimer and the C-terminal lobe of 14-3-3 observed in the crystal structure. Applied to other 14-3-3 complexes, the chimeric approach may help probe the stability and specificity of secondary interfaces for targeting them with small molecules in the future.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Time-Resolved Cryo-Electron Microscopy of Oscillating Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 502-503
Author(s):  
Eva-Maria Mandelkow ◽  
Ron Milligan
Keyword(s):  
Electron Microscopy ◽  
Dynamic Instability ◽  
Entire Solution ◽  
Reaction Scheme ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
A Chain ◽  
Ray Scattering

Microtubules form part of the cytoskeleton of eukaryotic cells. They are hollow libers of about 25 nm diameter made up of 13 protofilaments, each of which consists of a chain of heterodimers of α-and β-tubulin. Microtubules can be assembled in vitro at 37°C in the presence of GTP which is hydrolyzed during the reaction, and they are disassembled at 4°C. In contrast to most other polymers microtubules show the behavior of “dynamic instability”, i.e. they can switch between phases of growth and phases of shrinkage, even at an overall steady state [1]. In certain conditions an entire solution can be synchronized, leading to autonomous oscillations in the degree of assembly which can be observed by X-ray scattering (Fig. 1), light scattering, or electron microscopy [2-5]. In addition such solutions are capable of generating spontaneous spatial patterns [6].In an earlier study we have analyzed the structure of microtubules and their cold-induced disassembly by cryo-EM [7]. One result was that disassembly takes place by loss of protofilament fragments (tubulin oligomers) which fray apart at the microtubule ends. We also looked at microtubule oscillations by time-resolved X-ray scattering and proposed a reaction scheme [4] which involves a cyclic interconversion of tubulin, microtubules, and oligomers (Fig. 2). The present study was undertaken to answer two questions: (a) What is the nature of the oscillations as seen by time-resolved cryo-EM? (b) Do microtubules disassemble by fraying protofilament fragments during oscillations at 37°C?

X-ray scattering by 1D molecular Guinier-Preston zones in ordered smectic phases

1992 ◽  
Vol 2 (6) ◽  
pp. 899-913 ◽  
Author(s):  
Patrick Davidson ◽  
Elisabeth Dubois-Violette ◽  
Anne-Marie Levelut ◽  
Brigitte Pansu
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Smectic Phases ◽  
Ray Scattering

An X-ray Scattering Study of Laterally Modulated Structures: Investigation of Coherence and Resolution Effects with a Grating

1996 ◽  
Vol 6 (8) ◽  
pp. 1085-1094 ◽  
Author(s):  
A. Gibaud ◽  
J. Wang ◽  
M. Tolan ◽  
G. Vignaud ◽  
S. K. Sinha
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Modulated Structures ◽  
Scattering Study ◽  
Ray Scattering

Pixel detectors: New detectors for X-ray scattering

2002 ◽  
Vol 12 (6) ◽  
pp. 385-390 ◽  
Author(s):  
J.-F. Bérar ◽  
L. Blanquart ◽  
N. Boudet ◽  
P. Breugnon ◽  
B. Caillot ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Pixel Detectors ◽  
Ray Scattering

Study of crystallization of magnetron sputtered TiO2thin films by X-ray scattering

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 247-252
Author(s):  
R. Kužel ◽  
L. Nichtová ◽  
Z. Matěj ◽  
D. Heřman ◽  
J. Šicha ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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