Krios III-Titan Krios III at Diamond
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Manuel
Schweighauser
,
Diana
Arseni
,
Mehtap
Bacioglu
,
Melissa
Huang
,
Sofia
Lovestam
,
Yang
Shi
,
Yang
Yang
,
Wenjuan
Zhang
,
Abhay
Kotecha
,
Holly J.
Garringer
,
Ruben
Vidal
,
Grace I.
Hallin
,
Kathy L.
Newell
,
Airi
Tarutani
,
Shigeo
Murayama
,
Masayuki
Miyazaki
,
Yuko
Saito
,
Mari
Yoshida
,
Kazuko
Hasegawa
,
Tammaryn
Lashley
,
Tamas
Revesz
,
Gabor G.
Kovacs
,
John
Van Swieten
,
Masaki
Takao
,
Masato
Hasegawa
,
Bernardino
Ghetti
,
Maria Grazia
Spillantini
,
Benjamin
Ryskeldi-Falcon
,
Alexey G.
Murzin
,
Michel
Goedert
,
Sjors H. W.
Scheres
Diamond Proposal Number(s):
[17434, 23268]
Abstract: Many age-dependent neurodegenerative diseases, like Alzheimer’s and Parkinson’s, are characterised by abundant inclusions of amyloid filaments. Filamentous inclusions of the proteins tau, amyloid-β (Aβ), α-synuclein and TDP-43 are the most common1,2. Here, we used electron cryo-microscopy (cryo-EM) structure determination to show that residues 120-254 of the lysosomal type II transmembrane protein 106B (TMEM106B) also form amyloid filaments in human brains. We determined the cryo-EM structures of TMEM106B filaments from a number of brain regions of 22 individuals with abundant amyloid deposits, including sporadic and inherited tauopathies, Aβ-amyloidoses, synucleinopathies and TDP-43 proteinopathies, as well as from the frontal cortex of 3 neurologically normal individuals with no or only few amyloid deposits. We observed three TMEM106B folds, with no clear relationships between folds and diseases. TMEM106B filaments correlated with the presence of a 29 kDa sarkosyl-insoluble fragment and globular cytoplasmic inclusions, as detected by an antibody specific for the C-terminal region of TMEM106B. The identification of TMEM106B filaments in the brains of older, but not younger, neurologically normal individuals indicates that they form in an age-dependent manner.
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Mar 2022
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[18477]
Open Access
Abstract: Traditionally, molecular assembly pathways for viruses are inferred from high resolution structures of purified stable intermediates, low resolution images of cell sections and genetic approaches. Here, we directly visualise an unsuspected ‘single shelled’ intermediate for a mammalian orthoreovirus in cryo-preserved infected cells, by cryo-electron tomography of cellular lamellae. Particle classification and averaging yields structures to 5.6 Å resolution, sufficient to identify secondary structural elements and produce an atomic model of the intermediate, comprising 120 copies each of protein λ1 and σ2. This λ1 shell is ‘collapsed’ compared to the mature virions, with molecules pushed inwards at the icosahedral fivefolds by ~100 Å, reminiscent of the first assembly intermediate of certain prokaryotic dsRNA viruses. This supports the supposition that these viruses share a common ancestor, and suggests mechanisms for the assembly of viruses of the Reoviridae. Such methodology holds promise for dissecting the replication cycle of many viruses.
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Sep 2020
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Krios III-Titan Krios III at Diamond
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Pranav N. M.
Shah
,
James B.
Gilchrist
,
Björn O.
Forsberg
,
Alister
Burt
,
Andrew
Howe
,
Shyamal
Mosalaganti
,
William
Wan
,
Julika
Radecke
,
Yuriy
Chaban
,
Geoff
Sutton
,
David I.
Stuart
,
Mark
Boyce
Diamond Proposal Number(s):
[21004]
Open Access
Abstract: Rotavirus assembly is a complex process that involves the stepwise acquisition of protein layers in distinct intracellular locations to form the fully assembled particle. Understanding and visualization of the assembly process has been hampered by the inaccessibility of unstable intermediates. We characterize the assembly pathway of group A rotaviruses observed in situ within cryo-preserved infected cells through the use of cryoelectron tomography of cellular lamellae. Our findings demonstrate that the viral polymerase VP1 recruits viral genomes during particle assembly, as revealed by infecting with a conditionally lethal mutant. Additionally, pharmacological inhibition to arrest the transiently enveloped stage uncovered a unique conformation of the VP4 spike. Subtomogram averaging provided atomic models of four intermediate states, including a pre-packaging single-layered intermediate, the double-layered particle, the transiently enveloped double-layered particle, and the fully assembled triple-layered virus particle. In summary, these complementary approaches enable us to elucidate the discrete steps involved in forming an intracellular rotavirus particle.
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Mar 2023
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[17434]
Open Access
Abstract: Dyneins are motor proteins responsible for transport in the cytoplasm and the beating of axonemes in cilia and flagella. They bind and release microtubules via a compact microtubule-binding domain (MTBD) at the end of a coiled-coil stalk. We address how cytoplasmic and axonemal dynein MTBDs bind microtubules at near atomic resolution. We decorated microtubules with MTBDs of cytoplasmic dynein-1 and axonemal dynein DNAH7 and determined their cryo-EM structures using helical Relion. The majority of the MTBD is rigid upon binding, with the transition to the high-affinity state controlled by the movement of a single helix at the MTBD interface. DNAH7 contains an 18-residue insertion, found in many axonemal dyneins, that contacts the adjacent protofilament. Unexpectedly, we observe that DNAH7, but not dynein-1, induces large distortions in the microtubule cross-sectional curvature. This raises the possibility that dynein coordination in axonemes is mediated via conformational changes in the microtubule.
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Jul 2019
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[19865]
Open Access
Abstract: Yeast Tel1 and its highly conserved human ortholog ataxia-telangiectasia mutated (ATM) are large protein kinases central to the maintenance of genome integrity. Mutations in ATM are found in ataxia-telangiectasia (A-T) patients and ATM is one of the most frequently mutated genes in many cancers. Using cryoelectron microscopy, we present the structure of Tel1 in a nucleotide-bound state. Our structure reveals molecular details of key residues surrounding the nucleotide binding site and provides a structural and molecular basis for its intrinsically low basal activity. We show that the catalytic residues are in a productive conformation for catalysis, but the phosphatidylinositol 3-kinase-related kinase (PIKK) regulatory domain insert restricts peptide substrate access and the N-lobe is in an open conformation, thus explaining the requirement for Tel1 activation. Structural comparisons with other PIKKs suggest a conserved and common allosteric activation mechanism. Our work also provides a structural rationale for many mutations found in A-T and cancer.
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Nov 2019
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[19832]
Open Access
Abstract: The O-linked β-N-acetylglucosamine modification is a core signalling mechanism, with erroneous patterns leading to cancer and neurodegeneration. Although thousands of proteins are subject to this modification, only a single essential glycosyltransferase catalyses its installation, the O-GlcNAc transferase, OGT. Previous studies have provided truncated structures of OGT through X-ray crystallography, but the full-length protein has never been observed. Here, we report a 5.3 Å cryo-EM model of OGT. We show OGT is a dimer, providing a structural basis for how some X-linked intellectual disability mutations at the interface may contribute to disease. We observe that the catalytic section of OGT abuts a 13.5 tetratricopeptide repeat unit region and find the relative positioning of these sections deviate from the previously proposed, X-ray crystallography-based model. We also note that OGT exhibits considerable heterogeneity in tetratricopeptide repeat units N-terminal to the dimer interface with repercussions for how OGT binds protein ligands and partners.
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Nov 2021
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[18074]
Open Access
Abstract: Mitochondrial complex I (NADH:ubiquinone oxidoreductase), a crucial enzyme in energy metabolism, captures the redox potential energy from NADH oxidation and ubiquinone reduction to create the proton motive force used to drive ATP synthesis in oxidative phosphorylation. Recent high-resolution cryo-EM analyses have provided detailed structural knowledge of the catalytic machinery of complex I, but not of the molecular principles of its energy transduction mechanism. Although ubiquinone is considered to bind in a long channel at the interface of the membrane-embedded and hydrophilic domains, and channel residues are likely involved in coupling substrate reduction to proton translocation, no structures with the channel fully occupied have yet been described. Here, we report the cryo-EM structure of mouse complex I with an extremely tight-binding natural-product acetogenin inhibitor, which resembles the native substrate, bound along the full length of the expected ubiquinone-binding channel. Our structure reveals the mode of acetogenin binding and the molecular basis for structure–activity relationships within the acetogenin family. It also shows that acetogenins are such potent inhibitors because they are highly hydrophobic molecules that contain two specific hydrophilic moieties ideally spaced to lock into two hydrophilic regions of the otherwise hydrophobic channel. The central hydrophilic section of the channel does not favor binding of the isoprenoid chain when the native substrate is fully bound, but stabilises the ubiquinone/ubiquinol headgroup as it transits to/from the active site. Therefore, the amphipathic nature of the channel supports both tight binding of the amphipathic inhibitor and rapid exchange of the ubiquinone/ubiquinol substrate and product.
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Jan 2022
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Krios II-Titan Krios II at Diamond
Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[15997, 22006]
Open Access
Abstract: Pyruvate carboxylase (PC) is a tetrameric enzyme that contains two active sites per subunit that catalyze two consecutive reactions. A mobile domain with an attached prosthetic biotin links both reactions, an initial biotin carboxylation and the subsequent carboxyl transfer to pyruvate substrate to produce oxaloacetate. Reaction sites are at long distance, and there are several co-factors that play as allosteric regulators. Here, using cryoEM we explore the structure of active PC tetramers focusing on active sites and on the conformational space of the oligomers. The results capture the mobile domain at both active sites and expose catalytic steps of both reactions at high resolution, allowing the identification of substrates and products. The analysis of catalytically active PC tetramers reveals the role of certain motions during enzyme functioning, and the structural changes in the presence of additional cofactors expose the mechanism for allosteric regulation.
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Oct 2022
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Krios I-Titan Krios I at Diamond
Krios II-Titan Krios II at Diamond
Krios III-Titan Krios III at Diamond
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Luiza
Mendonca
,
Dapeng
Sun
,
Jiying
Ning
,
Jiwei
Liu
,
Abhay
Kotecha
,
Mateusz
Olek
,
Thomas
Frosio
,
Xiaofeng
Fu
,
Benjamin A.
Himes
,
Alex B.
Kleinpeter
,
Eric O.
Freed
,
Jing
Zhou
,
Christopher
Aiken
,
Peijun
Zhang
Diamond Proposal Number(s):
[18477, 21005, 21004]
Open Access
Abstract: Gag is the HIV structural precursor protein which is cleaved by viral protease to produce mature infectious viruses. Gag is a polyprotein composed of MA (matrix), CA (capsid), SP1, NC (nucleocapsid), SP2 and p6 domains. SP1, together with the last eight residues of CA, have been hypothesized to form a six-helix bundle responsible for the higher-order multimerization of Gag necessary for HIV particle assembly. However, the structure of the complete six-helix bundle has been elusive. Here, we determined the structures of both Gag in vitro assemblies and Gag viral-like particles (VLPs) to 4.2 Å and 4.5 Å resolutions using cryo-electron tomography and subtomogram averaging by emClarity. A single amino acid mutation (T8I) in SP1 stabilizes the six-helix bundle, allowing to discern the entire CA-SP1 helix connecting to the NC domain. These structures provide a blueprint for future development of small molecule inhibitors that can lock SP1 in a stable helical conformation, interfere with virus maturation, and thus block HIV-1 infection.
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Apr 2021
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Krios III-Titan Krios III at Diamond
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Diamond Proposal Number(s):
[24039]
Open Access
Abstract: Hypertension (high blood pressure) is a major risk factor for cardiovascular disease, which is the leading cause of death worldwide. The somatic isoform of angiotensin I-converting enzyme (sACE) plays a critical role in blood pressure regulation, and ACE inhibitors are thus widely used to treat hypertension and cardiovascular disease. Our current understanding of sACE structure, dynamics, function, and inhibition has been limited because truncated, minimally glycosylated forms of sACE are typically used for X-ray crystallography and molecular dynamics simulations. Here, we report the first cryo-EM structures of full-length, glycosylated, soluble sACE (sACES1211). Both monomeric and dimeric forms of the highly flexible apo enzyme were reconstructed from a single dataset. The N- and C-terminal domains of monomeric sACES1211 were resolved at 3.7 and 4.1 Å, respectively, while the interacting N-terminal domains responsible for dimer formation were resolved at 3.8 Å. Mechanisms are proposed for intradomain hinging, cooperativity, and homodimerization. Furthermore, the observation that both domains were in the open conformation has implications for the design of sACE modulators.
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Jul 2022
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