scholarly journals Molecular architecture of black widow spider neurotoxins

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Minghao Chen ◽  
Daniel Blum ◽  
Lena Engelhard ◽  
Stefan Raunser ◽  
Richard Wagner ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Calcium Flux ◽  
Membrane Insertion ◽  
Molecular Architecture ◽  
Cyclic Mechanism ◽  
High Resolution Structure ◽  
Specific Receptors ◽  
Β Sheet ◽  
Widow Spider ◽  
Resolution Structure

AbstractLatrotoxins (LaTXs) are presynaptic pore-forming neurotoxins found in the venom of Latrodectus spiders. The venom contains a toxic cocktail of seven LaTXs, with one of them targeting vertebrates (α-latrotoxin (α-LTX)), five specialized on insects (α, β, γ, δ, ε- latroinsectotoxins (LITs), and one on crustaceans (α-latrocrustatoxin (α-LCT)). LaTXs bind to specific receptors on the surface of neuronal cells, inducing the release of neurotransmitters either by directly stimulating exocytosis or by forming Ca2+-conductive tetrameric pores in the membrane. Despite extensive studies in the past decades, a high-resolution structure of a LaTX is not yet available and the precise mechanism of LaTX action remains unclear. Here, we report cryoEM structures of the α-LCT monomer and the δ-LIT dimer. The structures reveal that LaTXs are organized in four domains. A C-terminal domain of ankyrin-like repeats shields a central membrane insertion domain of six parallel α-helices. Both domains are flexibly linked via an N-terminal α-helical domain and a small β-sheet domain. A comparison between the structures suggests that oligomerization involves major conformational changes in LaTXs with longer C-terminal domains. Based on our data we propose a cyclic mechanism of oligomerization, taking place prior membrane insertion. Both recombinant α-LCT and δ-LIT form channels in artificial membrane bilayers, that are stabilized by Ca2+ ions and allow calcium flux at negative membrane potentials. Our comparative analysis between α-LCT and δ-LIT provides first crucial insights towards understanding the molecular mechanism of the LaTX family.

scholarly journals Molecular architecture of black widow spider neurotoxins

2021 ◽  
Author(s):  
Minghao Chen ◽  
Daniel Blum ◽  
Lena Engelhard ◽  
Stefan Raunser ◽  
Richard Wagner ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Calcium Flux ◽  
Membrane Insertion ◽  
Molecular Architecture ◽  
Cyclic Mechanism ◽  
High Resolution Structure ◽  
Specific Receptors ◽  
Β Sheet ◽  
Widow Spider ◽  
Resolution Structure

AbstractLatrotoxins (LaTXs) are presynaptic pore-forming neurotoxins found in the venom of Latrodectus spiders. The venom contains a toxic cocktail of seven LaTXs, with one of them targeting vertebrates (α-latrotoxin (α-LTX)), five specialized on insects (α, β, γ, δ, ɛ-latroinsectotoxins (LITs), and one on crustaceans (α-latrocrustatoxin (α-LCT)). LaTXs bind to specific receptors on the surface of neuronal cells, inducing the release of neurotransmitters either by directly stimulating exocytosis or by forming Ca2+-conductive tetrameric pores in the membrane. Despite extensive studies in the past decades, a high-resolution structure of a LaTX is not yet available and the precise mechanism of LaTX action remains unclear.Here, we report cryoEM structures of the α-LCT monomer and the δ-LIT dimer. The structures reveal that LaTXs are organized in four domains. A C-terminal domain of ankyrin-like repeats shields a central membrane insertion domain of six parallel α-helices. Both domains are flexibly linked via an N-terminal α-helical domain and a small β-sheet domain. A comparison between the structures suggests that oligomerization involves major conformational changes in LaTXs with longer C-terminal domains. Based on our data we propose a cyclic mechanism of oligomerization, taking place prior membrane insertion. Both recombinant α-LCT and δ-LIT form channels in artificial membrane bilayers, that are stabilized by Ca2+ ions and allow calcium flux at negative membrane potentials. Our comparative analysis between α-LCT and δ-LIT provides first crucial insights towards understanding the molecular mechanism of the LaTX family.

scholarly journals High-Resolution Structure of a Self-Assembly-Competent Form of a Hydrophobic Peptide Captured in a Soluble β-Sheet Scaffold

2008 ◽  
Vol 378 (2) ◽  
pp. 459-467 ◽  
Author(s):  
Koki Makabe ◽  
Matthew Biancalana ◽  
Shude Yan ◽  
Valentina Tereshko ◽  
Grzegorz Gawlak ◽  
...  
Keyword(s):  
High Resolution ◽  
Self Assembly ◽  
Hydrophobic Peptide ◽  
High Resolution Structure ◽  
Β Sheet ◽  
Resolution Structure

scholarly journals Structural basis for the regulatory function of a complex zinc-binding domain in a replicative arterivirus helicase resembling a nonsense-mediated mRNA decay helicase

2013 ◽  
Vol 42 (5) ◽  
pp. 3464-3477 ◽  
Author(s):  
Zengqin Deng ◽  
Kathleen C. Lehmann ◽  
Xiaorong Li ◽  
Chong Feng ◽  
Guoqiang Wang ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Binding Domain ◽  
Zinc Binding ◽  
Regulatory Function ◽  
Structural Basis ◽  
Genome Replication ◽  
High Resolution Structure ◽  
Nonsense Mediated Mrna Decay ◽  
Zinc Binding Domain ◽  
Resolution Structure

AbstractAll positive-stranded RNA viruses with genomes >∼7 kb encode helicases, which generally are poorly characterized. The core of the nidovirus superfamily 1 helicase (HEL1) is associated with a unique N-terminal zinc-binding domain (ZBD) that was previously implicated in helicase regulation, genome replication and subgenomic mRNA synthesis. The high-resolution structure of the arterivirus helicase (nsp10), alone and in complex with a polynucleotide substrate, now provides first insights into the structural basis for nidovirus helicase function. A previously uncharacterized domain 1B connects HEL1 domains 1A and 2A to a long linker of ZBD, which further consists of a novel RING-like module and treble-clef zinc finger, together coordinating three Zn atoms. On substrate binding, major conformational changes were evident outside the HEL1 domains, notably in domain 1B. Structural characterization, mutagenesis and biochemistry revealed that helicase activity depends on the extensive relay of interactions between the ZBD and HEL1 domains. The arterivirus helicase structurally resembles the cellular Upf1 helicase, suggesting that nidoviruses may also use their helicases for post-transcriptional quality control of their large RNA genomes.

scholarly journals Genuine open form of the pentameric ligand-gated ion channel GLIC

2015 ◽  
Vol 71 (3) ◽  
pp. 454-460 ◽  
Author(s):  
Zaineb Fourati ◽  
Ludovic Sauguet ◽  
Marc Delarue
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Conformational Changes ◽  
Computational Studies ◽  
Potential Influence ◽  
X Ray ◽  
Correct Assignment ◽  
High Resolution Structure ◽  
Fast Chemical ◽  
Resolution Structure

Pentameric ligand-gated ion channels (pLGICs) mediate fast chemical neurotransmission of nerve signalling in the central and peripheral nervous systems. GLIC is a bacterial homologue of eukaryotic pLGIC, the X-ray structure of which has been determined in three different conformations. GLIC is thus widely used as a model to study the activation and the allosteric transition of this family of receptors. The recently solved high-resolution structure of GLIC (2.4 Å resolution) in the active state revealed two bound acetate molecules in the extracellular domain (ECD). Here, it is shown that these two acetates exactly overlap with known sites of pharmacological importance in pLGICs, and their potential influence on the structure of the open state is studied in detail. Firstly, experimental evidence is presented for the correct assignment of these acetate molecules by using the anomalous dispersion signal of bromoacetate. Secondly, the crystal structure of GLIC in the absence of acetate was solved and it is shown that acetate binding induces local conformational changes that occur in strategic sites of the ECD. It is expected that this acetate-free structure will be useful in future computational studies of the gating transition in GLIC and other pLGICs.

scholarly journals Structural Basis of RNA Cap Modification by SARS-CoV-2 Coronavirus

2020 ◽  
Author(s):  
Thiruselvam Viswanathan ◽  
Shailee Arya ◽  
Siu-Hong Chan ◽  
Shan Qi ◽  
Nan Dai ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Innate Immune ◽  
Structural Basis ◽  
The Novel ◽  
Structural Protein ◽  
High Resolution Structure ◽  
Cellular Mrnas ◽  
Adenosyl Methionine ◽  
Ribose Sugar ◽  
Resolution Structure

AbstractThe novel severe acute respiratory syndrome coronoavirus-2 (SARS-CoV-2), the causative agent of COVID-19 illness, has caused over 2 million infections worldwide in four months. In SARS coronaviruses, the non-structural protein 16 (nsp16) methylates the 5’-end of virally encoded mRNAs to mimic cellular mRNAs, thus protecting the virus from host innate immune restriction. We report here the high-resolution structure of a ternary complex of full-length nsp16 and nsp10 of SARS-CoV-2 in the presence of cognate RNA substrate and a methyl donor, S-adenosyl methionine. The nsp16/nsp10 heterodimer was captured in the act of 2’-O methylation of the ribose sugar of the first nucleotide of SARS-CoV-2 mRNA. We reveal large conformational changes associated with substrate binding as the enzyme transitions from a binary to a ternary state. This structure provides new mechanistic insights into the 2’-O methylation of the viral mRNA cap. We also discovered a distantly located ligand-binding site unique to SARS-CoV-2 that may serve as an alternative target site for antiviral development.

scholarly journals The pore conformation of lymphocyte perforin

2021 ◽  
Author(s):  
Marina Ivanova ◽  
Natalya Lukoyanova ◽  
Sony Malhotra ◽  
Maya Topf ◽  
Joseph A Trapani ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Target Cell ◽  
Pore Formation ◽  
Electron Tomography ◽  
Membrane Surface ◽  
Membrane Insertion ◽  
Cytotoxic Lymphocytes ◽  
Cryo Electron Tomography ◽  
Cancerous Cells ◽  
Β Sheet

Perforin is a pore-forming protein that facilitates rapid killing of pathogen-infected or cancerous cells by the immune system. Perforin is released from cytotoxic lymphocytes, together with pro-apoptotic granzymes, to bind to the plasma membrane of the target cell where it oligomerises and forms pores. The pores allow granzyme entry, which rapidly triggers the apoptotic death of the target cell. Here we present a 4 Å resolution cryo-EM structure of the perforin pore, revealing new inter- and intra-molecular interactions stabilising the pore. During assembly and pore formation, the helix-turn-helix motif at the bend in the central β-sheet moves away from the bend to form an intermolecular contact. Cryo-electron tomography shows that prepores form on the membrane surface with minimal conformational changes. Our findings suggest the sequence of conformational changes underlying oligomerisation and membrane insertion, and explain how several pathogenic mutations affect function.

scholarly journals High-resolution structures of malaria parasite actomyosin and actin filaments

2020 ◽  
Author(s):  
Juha Vahokoski ◽  
Lesley J. Calder ◽  
Andrea J. Lopez ◽  
Justin E. Molloy ◽  
Peter B. Rosenthal ◽  
...  
Keyword(s):  
High Resolution ◽  
Conformational Changes ◽  
Light Chain ◽  
Malaria Parasite ◽  
Gliding Motility ◽  
Light Chains ◽  
Motor Complex ◽  
Excellent Starting Point ◽  
High Resolution Structure ◽  
Resolution Structure

AbstractMalaria is responsible for half a million deaths annually and poses a huge economic burden on the developing world. The mosquito-borne parasites (Plasmodium spp.) that cause the disease depend upon an unconventional actomyosin motor for both gliding motility and host cell invasion. The motor system, often referred to as the glideosome complex, remains to be understood in molecular terms and is an attractive target for new drugs that might block the infection pathway. Here, we present the first high-resolution structure of the actomyosin motor complex from Plasmodium falciparum. Our structure includes the malaria parasite actin filament (PfAct1) complexed with the myosin motor (PfMyoA) and its two associated light-chains. The high-resolution core structure reveals the PfAct1:PfMyoA interface in atomic detail, while at lower-resolution, we visualize the PfMyoA light-chain binding region, including the essential light chain (PfELC) and the myosin tail interacting protein (PfMTIP). Finally, we report a bare PfAct1 filament structure at an improved resolution, which gives new information about the nucleotide-binding site, including the orientation of the ATP/ADP sensor, Ser15, and the presence of a channel, which we propose as a possible phosphate exit path after ATP hydrolysis.Significance statementWe present the first structure of the malaria parasite motor complex; actin 1 (PfAct1) and myosin A (PfMyoA) with its two light chains. We also report a high-resolution structure of filamentous PfAct1 that reveals new atomic details of the ATPase site, including a channel, which may provide an exit route for phosphate and explain why phosphate release is faster in PfAct1 compared to canonical actins. PfAct1 goes through no conformational changes upon PfMyoA binding. Our PfMyoA structure also superimposes with a recent crystal structure of PfMyoA alone, though there are small but important conformational changes at the interface. Our structures serve as an excellent starting point for drug design against malaria, which is one of the most devastating infectious diseases.

High-Resolution Structure of a Protein Spin-Label in a Solvent-Exposed β-Sheet and Comparison with DEER Spectroscopy

Biochemistry ◽  
2012 ◽  
Vol 51 (32) ◽  
pp. 6350-6359 ◽  
Author(s):  
Timothy F. Cunningham ◽  
Marshall S. McGoff ◽  
Ishita Sengupta ◽  
Christopher P. Jaroniec ◽  
W. Seth Horne ◽  
...  
Keyword(s):  
High Resolution ◽  
Spin Label ◽  
High Resolution Structure ◽  
Β Sheet ◽  
Resolution Structure

High-resolution structure determination by ALCHEMI

1983 ◽  
Vol 41 ◽  
pp. 178-181 ◽  
Author(s):  
Peter G. Self ◽  
Peter R. Buseck
Keyword(s):  
Site Occupancy ◽  
Real Space ◽  
Unit Cell ◽  
Bragg Angle ◽  
Electron Current ◽  
High Resolution Structure ◽  
Beam Incident ◽  
Crystallographic Planes ◽  
Electron Beam Incident ◽  
Resolution Structure

ALCHEMI (Atom Location by CHanneling Enhanced Microanalysis) enables the site occupancy of atoms in single crystals to be determined. In this article the fundamentals of the method for both EDS and EELS will be discussed. Unlike HRTEM, ALCHEMI does not place stringent resolution requirements on the microscope and, because EDS clearly distinguishes between elements of similar atomic number, it can offer some advantages over HRTEM. It does however, place certain constraints on the crystal. These constraints are: a) the sites of interest must lie on alternate crystallographic planes, b) the projected charge density on the alternate planes must be significantly different, and c) there must be at least one atomic species that lies solely on one of the planes.An electron beam incident on a crystal undergoes elastic scattering; in reciprocal space this is seen as a diffraction pattern and in real space this is a modulation of the electron current across the unit cell. When diffraction is strong (i.e., when the crystal is oriented near to the Bragg angle of a low-order reflection) the electron current at one point in the unit cell will differ significantly from that at another point.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

Sign in / Sign up

Export Citation Format

Share Document