I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[8997]
Open Access
Abstract: The thick filament-associated A-band region of titin is a highly repetitive component of the titin chain with important scaffolding properties that support thick filament assembly. It also has a demonstrated link to human disease. Despite its functional significance, it remains a largely uncharacterized part of the titin protein. Here, we have performed an analysis of sequence and structure conservation of A-band titin, with emphasis on poly-FnIII tandem components. Specifically, we have applied multi-dimensional sequence pairwise similarity analysis to FnIII domains and complemented this with the crystallographic elucidation of the 3D-structure of the FnIII-triplet A84-A86 from the fourth long super-repeat in the C-zone (C4). Structural models serve here as templates to map sequence conservation onto super-repeat C4, which we show is a prototypical representative of titin’s C-zone. This templating identifies positionally conserved residue clusters in C super-repeats with the potential of mediating interactions to thick-filament components. Conservation localizes to two super-repeat positions: Ig domains in position 1 and FnIII domains in position 7. The analysis also allows conclusions to be drawn on the conserved architecture of titin’s A-band, as well as revisiting and expanding the evolutionary model of titin’s A-band.
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May 2023
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Krios I-Titan Krios I at Diamond
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Xinrui
Huang
,
Iratxe
Torre
,
Michele
Chiappi
,
Zhan
Yin
,
Anupama
Vydyanath
,
Shuangyi
Cao
,
Oliver
Raschdorf
,
Morgan
Beeby
,
Bonnie
Quigley
,
Pieter P.
De Tombe
,
Jun
Liu
,
Edward P.
Morris
,
Pradeep K.
Luther
Diamond Proposal Number(s):
[18092]
Open Access
Abstract: Myosin binding protein C (MyBP-C) is an accessory protein of the thick filament in vertebrate cardiac muscle arranged over 9 stripes of intervals of 430 Å in each half of the A-band in the region called the C-zone. Mutations in cardiac MyBP-C are a leading cause of hypertrophic cardiomyopathy the mechanism of which is unknown. It is a rod-shaped protein composed of 10 or 11 immunoglobulin- or fibronectin-like domains labelled C0 to C10 which binds to the thick filament via its C-terminal region. MyBP-C regulates contraction in a phosphorylation dependent fashion that may be through binding of its N-terminal domains with myosin or actin. Understanding the 3D organisation of MyBP-C in the sarcomere environment may provide new light on its function. We report here the fine structure of MyBP-C in relaxed rat cardiac muscle by cryo-electron tomography and subtomogram averaging of refrozen Tokuyasu cryosections. We find that on average MyBP-C connects via its distal end to actin across a disc perpendicular to the thick filament. The path of MyBP-C suggests that the central domains may interact with myosin heads. Surprisingly MyBP-C at Stripe 4 is different; it has weaker density than the other stripes which could result from a mainly axial or wavy path. Given that the same feature at Stripe 4 can also be found in several mammalian cardiac muscles and in some skeletal muscles, our finding may have broader implication and significance. In the D-zone, we show the first demonstration of myosin crowns arranged on a uniform 143 Å repeat.
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Apr 2023
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I24-Microfocus Macromolecular Crystallography
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Peter T.
Buckley
,
Rita
Chan
,
Jeffrey
Fernandez
,
Jinquan
Luo
,
Keenan A.
Lacey
,
Ashley L.
Dumont
,
Aidan
O’malley
,
Randall J.
Brezski
,
Songmao
Zheng
,
Thomas
Malia
,
Brian
Whitaker
,
Adam
Zwolak
,
Angela
Payne
,
Desmond
Clark
,
Martin
Sigg
,
Eilyn R.
Lacy
,
Anna
Kornilova
,
Debra
Kwok
,
Steve
Mccarthy
,
Bingyuan
Wu
,
Brian
Morrow
,
Jennifer
Nemeth-Seay
,
Ted
Petley
,
Sam
Wu
,
William R.
Strohl
,
Anthony S.
Lynch
,
Victor J.
Torres
Open Access
Abstract: Treating and preventing infections by antimicrobial-resistant bacterial pathogens is a worldwide problem. Pathogens such as Staphylococcus aureus produce an array of virulence determinants, making it difficult to identify single targets for the development of vaccines or monoclonal therapies. We described a human-derived anti-S. aureus monoclonal antibody (mAb)-centyrin fusion protein (“mAbtyrin”) that simultaneously targets multiple bacterial adhesins, resists proteolysis by bacterial protease GluV8, avoids Fc engagement by S. aureus IgG-binding proteins SpA and Sbi, and neutralizes pore-forming leukocidins via fusion with anti-toxin centyrins, while maintaining Fc- and complement-mediated functions. Compared with the parental mAb, mAbtyrin protected human phagocytes and boosted phagocyte-mediated killing. The mAbtyrin also reduced pathology, reduced bacterial burden, and protected from different types of infections in preclinical animal models. Finally, mAbtyrin synergized with vancomycin, enhancing pathogen clearance in an animal model of bacteremia. Altogether, these data establish the potential of multivalent mAbs for treating and preventing S. aureus diseases.
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Apr 2023
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I03-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[9306, 12346]
Open Access
Abstract: Structurally complex genomic regions, such as centromeres, are inherently difficult to duplicate. The mechanism behind centromere inheritance is not well understood, and one of the key questions relates to the reassembly of centromeric chromatin following DNA replication. Here, we define ERCC6L2 as a key regulator of this process. ERCC6L2 accumulates at centromeres and promotes deposition of core centromeric factors. Interestingly, ERCC6L2−/− cells show unrestrained replication of centromeric DNA, likely caused by the erosion of centromeric chromatin. Beyond centromeres, ERCC6L2 facilitates replication at genomic repeats and non-canonical DNA structures. Notably, ERCC6L2 interacts with the DNA-clamp PCNA through an atypical peptide, presented here in a co-crystal structure. Finally, ERCC6L2 also restricts DNA end resection, acting independently of the 53BP1-REV7-Shieldin complex. We propose a mechanistic model, which reconciles seemingly distinct functions of ERCC6L2 in DNA repair and DNA replication. These findings provide a molecular context for studies linking ERCC6L2 to human disease.
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Apr 2023
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I03-Macromolecular Crystallography
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Aiste
Dijokaite-Guraliuc
,
Raksha
Das
,
Daming
Zhou
,
Helen M.
Ginn
,
Chang
Liu
,
Helen M. E.
Duyvesteyn
,
Jiandong
Huo
,
Rungtiwa
Nutalai
,
Piyada
Supasa
,
Muneeswaran
Selvaraj
,
Thushan I.
De Silva
,
Megan
Plowright
,
Thomas A. H.
Newman
,
Hailey
Hornsby
,
Alexander J.
Mentzer
,
Donal
Skelly
,
Thomas G.
Ritter
,
Nigel
Temperton
,
Paul
Klenerman
,
Eleanor
Barnes
,
Susanna J.
Dunachie
,
Cornelius
Roemer
,
Thomas P.
Peacock
,
Neil G.
Paterson
,
Mark A.
Williams
,
David R.
Hall
,
Elizabeth E.
Fry
,
Juthathip
Mongkolsapaya
,
Jingshan
Ren
,
David I.
Stuart
,
Gavin R.
Screaton
Diamond Proposal Number(s):
[27009]
Open Access
Abstract: In November 2021 Omicron BA.1, containing a raft of new spike mutations emerged and quickly spread globally. Intense selection pressure to escape the antibody response produced by vaccines or SARS-CoV-2 infection then led to a rapid succession of Omicron sub-lineages with waves of BA.2 then BA.4/5 infection. Recently, many variants have emerged such as BQ.1 and XBB, which carry up to 8 additional RBD amino-acid substitutions compared to BA.2. We describe a panel of 25 potent mAbs generated from vaccinees suffering BA.2 breakthrough infections. Epitope mapping shows potent mAb binding shifting to 3 clusters, 2 corresponding to early-pandemic binding hotspots. The RBD mutations in recent variants map close to these binding sites and knock out or severely knock down neutralization activity of all but 1 potent mAb. This recent mAb escape corresponds with large falls in neutralization titre of vaccine or BA.1, BA.2 or BA.4/5 immune serum.
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Mar 2023
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I03-Macromolecular Crystallography
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Anastasia
Gkeka
,
Francisco
Aresta-Branco
,
Gianna
Triller
,
Evi P.
Vlachou
,
Monique
Van Straaten
,
Mirjana
Lilic
,
Paul Dominic B.
Olinares
,
Kathryn
Perez
,
Brian T.
Chait
,
Renata
Blatnik
,
Thomas
Ruppert
,
Joseph P.
Verdi
,
C. Erec
Stebbins
,
F. Nina
Papavasiliou
Diamond Proposal Number(s):
[24246]
Open Access
Abstract: The African trypanosome survives the immune response of its mammalian host by antigenic variation of its major surface antigen (the variant surface glycoprotein or VSG). Here we describe the antibody repertoires elicited by different VSGs. We show that the repertoires are highly restricted and are directed predominantly to distinct epitopes on the surface of the VSGs. They are also highly discriminatory; minor alterations within these exposed epitopes confer antigenically distinct properties to these VSGs and elicit different repertoires. We propose that the patterned and repetitive nature of the VSG coat focuses host immunity to a restricted set of immunodominant epitopes per VSG, eliciting a highly stereotyped response, minimizing cross-reactivity between different VSGs and facilitating prolonged immune evasion through epitope variation.
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Mar 2023
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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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I03-Macromolecular Crystallography
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Jiandong
Huo
,
Aiste
Dijokaite-Guraliuc
,
Chang
Liu
,
Raksha
Das
,
Piyada
Supasa
,
Muneeswaran
Selvaraj
,
Rungtiwa
Nutalai
,
Daming
Zhou
,
Alexander J.
Mentzer
,
Donal
Skelly
,
Thomas G.
Ritter
,
Ali
Amini
,
Sagida
Bibi
,
Sandra
Adele
,
Sile Ann
Johnson
,
Neil G.
Paterson
,
Mark A.
Williams
,
David R.
Hall
,
Megan
Plowright
,
Thomas A. H.
Newman
,
Hailey
Hornsby
,
Thushan I.
De Silva
,
Nigel
Temperton
,
Paul
Klenerman
,
Eleanor
Barnes
,
Susanna J.
Dunachie
,
Andrew J.
Pollard
,
Teresa
Lambe
,
Philip
Goulder
,
Elizabeth E.
Fry
,
Juthathip
Mongkolsapaya
,
Jingshan
Ren
,
David I.
Stuart
,
Gavin R.
Screaton
Diamond Proposal Number(s):
[27009]
Open Access
Abstract: Variants of SARS CoV-2 have caused successive global waves of infection. These variants, with multiple mutations in the spike protein are thought to facilitate escape from natural and vaccine-induced immunity and often increase in the affinity for ACE2. The latest variant to cause concern is BA.2.75, identified in India where it is now the dominant strain, with evidence of wider dissemination. BA.2.75 is derived from BA.2 and contains four additional mutations in the receptor binding domain (RBD). Here we perform an antigenic and biophysical characterization of BA.2.75, revealing an interesting balance between humoral evasion and ACE2 receptor affinity. ACE2 affinity for BA.2.75 is increased 9-fold compared to BA.2; there is also evidence of escape of BA.2.75 from immune serum, particularly that induced by Delta infection which may explain the rapid spread in India, where BA.2.75 is now the dominant variant. ACE2 affinity appears to be prioritised over greater escape.
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Dec 2022
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I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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Diamond Proposal Number(s):
[21426]
Open Access
Abstract: Transcriptional silencing through the Polycomb silencing machinery utilizes a “read-write” mechanism involving histone tail modifications. However, nucleation of silencing and long-term stable transmission of the silenced state also requires P-olycomb Repressive Complex 2 (PRC2) accessory proteins, whose molecular role is poorly understood. The Arabidopsis VEL proteins are accessory proteins that interact with PRC2 to nucleate and propagate silencing at the FLOWERING LOCUS C (FLC) locus, enabling early flowering in spring. Here, we report that VEL proteins contain a domain related to an atypical four-helix bundle that engages in spontaneous concentration-dependent head-to-tail polymerization to assemble dynamic biomolecular condensates. Mutations blocking polymerization of this VEL domain prevent Polycomb silencing at FLC. Plant VEL proteins thus facilitate assembly of dynamic multivalent Polycomb complexes required for inheritance of the silenced state.
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Nov 2022
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I03-Macromolecular Crystallography
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Jiandong
Huo
,
Aiste
Dijokaite-Guraliuc
,
Rungtiwa
Nutalai
,
Raksha
Das
,
Daming
Zhou
,
Alexander J.
Mentzer
,
Elizabeth E.
Fry
,
Juthathip
Mongkolsapaya
,
Jingshan
Ren
,
David I.
Stuart
,
Gavin R.
Screaton
Diamond Proposal Number(s):
[27009]
Open Access
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Nov 2022
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