I03-Macromolecular Crystallography
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Daniel
Del Toro
,
Maria A.
Carrasquero-ordaz
,
Amy
Chu
,
Tobias
Ruff
,
Meriam
Shahin
,
Verity A.
Jackson
,
Matthieu
Chavent
,
Miguel
Berbeira-santana
,
Goenuel
Seyit-bremer
,
Sara
Brignani
,
Rainer
Kaufmann
,
Edward
Lowe
,
Rüdiger
Klein
,
Elena
Seiradake
Diamond Proposal Number(s):
[12346, 1838]
Open Access
Abstract: Teneurins are ancient metazoan cell adhesion receptors that control brain development and neuronal wiring in higher animals. The extracellular C terminus binds the adhesion GPCR Latrophilin, forming a trans-cellular complex with synaptogenic functions. However, Teneurins, Latrophilins, and FLRT proteins are also expressed during murine cortical cell migration at earlier developmental stages. Here, we present crystal structures of Teneurin-Latrophilin complexes that reveal how the lectin and olfactomedin domains of Latrophilin bind across a spiraling beta-barrel domain of Teneurin, the YD shell. We couple structure-based protein engineering to biophysical analysis, cell migration assays, and in utero electroporation experiments to probe the importance of the interaction in cortical neuron migration. We show that binding of Latrophilins to Teneurins and FLRTs directs the migration of neurons using a contact repulsion-dependent mechanism. The effect is observed with cell bodies and small neurites rather than their processes. The results exemplify how a structure-encoded synaptogenic protein complex is also used for repulsive cell guidance.
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Jan 2020
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I03-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[18566]
Open Access
Abstract: Protein ubiquitination plays a key role in the regulation of cellular processes, and misregulation of the ubiquitin system is linked to many diseases. So far, development of tool compounds that target enzymes of the ubiquitin system has been slow and only a few specific inhibitors are available. Here, we report the selection of single-domain antibodies (single-dAbs) based on a human scaffold that recognize the catalytic domain of HOIP, a subunit of the multi-component E3 LUBAC and member of the RBR family of E3 ligases. Some of these dAbs affect ligase activity and provide mechanistic insight into the ubiquitin transfer mechanism of different E2-conjugating enzymes. Furthermore, we show that the co-crystal structure of a HOIP RBR/dAb complex serves as a robust platform for soaking of ligands that target the active site cysteine of HOIP, thereby providing easy access to structure-based ligand design for this important class of E3 ligases.
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Dec 2019
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I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[21969]
Open Access
Abstract: RNA polymerase II transcripts receive a protective 5',5'-triphosphate-linked 7-methylguanosine (m7G) cap, and its removal by decapping enzymes like DCP2 is critical for initiation of RNA decay. Alternative RNA caps can be acquired when transcription initiation uses metabolites like nicotinamide adenine dinucleotide (NAD), generating NAD-RNAs. Here, we identify human NUDT12 as a cytosolic NAD-RNA decapping enzyme. NUDT12 is active only as homodimers, with each monomer contributing to creation of the two functional catalytic pockets. We identify an ∼600-kDa dodecamer complex between bleomycin hydrolase (BLMH) and NUDT12, with BLMH being required for localization of NUDT12 to a few discrete cytoplasmic granules that are distinct from P-bodies. Both proteins downregulate gene expression when artificially tethered to a reporter RNA in vivo. Furthermore, loss of Nudt12 results in a significant upregulation of circadian clock transcripts in mouse liver. Overall, our study points to a physiological role for NUDT12 in the cytosolic surveillance of NAD-RNAs.
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Dec 2019
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I24-Microfocus Macromolecular Crystallography
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Donna L.
Mallery
,
K. M. Rifat
Faysal
,
Alex
Kleinpeter
,
Miranda S. C.
Wilson
,
Marina
Vaysburd
,
Adam J.
Fletcher
,
Mariia
Novikova
,
Till
Böcking
,
Eric O.
Freed
,
Adolfo
Saiardi
,
Leo C.
James
Diamond Proposal Number(s):
[15916]
Open Access
Abstract: HIV-1 hijacks host proteins to promote infection. Here we show that HIV is also dependent upon the host metabolite inositol hexakisphosphate (IP6) for viral production and primary cell replication. HIV-1 recruits IP6 into virions using two lysine rings in its immature hexamers. Mutation of either ring inhibits IP6 packaging and reduces viral production. Loss of IP6 also results in virions with highly unstable capsids, leading to a profound loss of reverse transcription and cell infection. Replacement of one ring with a hydrophobic isoleucine core restores viral production, but IP6 incorporation and infection remain impaired, consistent with an independent role for IP6 in stable capsid assembly. Genetic knockout of biosynthetic kinases IPMK and IPPK reveals that cellular IP6 availability limits the production of diverse lentiviruses, but in the absence of IP6, HIV-1 packages IP5 without loss of infectivity. Together, these data suggest that IP6 is a critical cofactor for HIV-1 replication.
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Dec 2019
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I03-Macromolecular Crystallography
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Open Access
Abstract: Background: Olfactomedin-1 (Olfm1; also known as Noelin or Pancortin) is a highly-expressed secreted brain and retina protein and its four isoforms have different roles in nervous system development and function. Structural studies showed that the long Olfm1 isoform BMZ forms a disulfide-linked tetramer with a V-shaped architecture. The tips of the Olfm1 “V” each consist of two C-terminal β-propeller domains that enclose a calcium binding site. Functional characterisation of Olfm1 may be aided by new biochemical tools derived from these core structural elements. Results: Here we present the production, purification and structural analysis of three novel monomeric, dimeric and tetrameric forms of mammalian Olfm1 for functional studies. We characterise these constructs structurally by high-resolution X-ray crystallography and small-angle X-ray scattering. The crystal structure of the Olfm1 β-propeller domain (to 1.25 Å) represents the highest-resolution structure of an olfactomedin family member to date, revealing features such as a hydrophilic tunnel containing water molecules running into the core of the domain where the calcium binding site resides. The shorter Olfactomedin-1 isoform BMY is a disulfide-linked tetramer with a shape similar to the corresponding region in the longer BMZ isoform. Conclusions: These recombinantly-expressed protein tools should assist future studies, for example of biophysical, electrophysiological or morphological nature, to help elucidate the functions of Olfm1 in the mature mammalian brain. The control over the oligomeric state of Olfm1 provides a firm basis to better understand the role of Olfm1 in the (trans-synaptic) tethering or avidity-mediated clustering of synaptic receptors such as post-synaptic AMPA receptors and pre-synaptic amyloid precursor protein. In addition, the variation in domain composition of these protein tools provides a means to dissect the Olfm1 regions important for receptor binding.
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Nov 2019
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I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
Krios I-Titan Krios I at Diamond
Krios II-Titan Krios II at Diamond
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Diamond Proposal Number(s):
[13062, 17844, 21288, 21404]
Abstract: Niemann-Pick type C (NPC) proteins are essential for sterol homeostasis, believed to drive sterol integration into the lysosomal membrane before redistribution to other cellular membranes. Here, using a combination of crystallography, cryo-electron microscopy, and biochemical and in vivo studies on the Saccharomyces cerevisiae NPC system (NCR1 and NPC2), we present a framework for sterol membrane integration. Sterols are transferred between hydrophobic pockets of vacuolar NPC2 and membrane-protein NCR1. NCR1 has its N-terminal domain (NTD) positioned to deliver a sterol to a tunnel connecting NTD to the luminal membrane leaflet 50 Å away. A sterol is caught inside this tunnel during transport, and a proton-relay network of charged residues in the transmembrane region is linked to this tunnel supporting a proton-driven transport mechanism. We propose a model for sterol integration that clarifies the role of NPC proteins in this essential eukaryotic pathway and that rationalizes mutations in patients with Niemann-Pick disease type C.
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Oct 2019
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I02-Macromolecular Crystallography
I04-Macromolecular Crystallography
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Thomas E.
Wood
,
Sophie A.
Howard
,
Andreas
Forster
,
Laura M.
Nolan
,
Eleni
Manoli
,
Nathan P.
Bullen
,
Hamish C. L.
Yau
,
Abderrahman
Hachani
,
Richard D.
Hayward
,
John C.
Whitney
,
Waldemar
Vollmer
,
Paul S.
Freemont
,
Alain
Filloux
Open Access
Abstract: The type VI secretion system (T6SS) is crucial in interbacterial competition and is a virulence determinant of many Gram-negative bacteria. Several T6SS effectors are covalently fused to secreted T6SS structural components such as the VgrG spike for delivery into target cells. In Pseudomonas aeruginosa, the VgrG2b effector was previously proposed to mediate bacterial internalization into eukaryotic cells. In this work, we find that the VgrG2b C-terminal domain (VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein. We resolve the structure of VgrG2bC-ter and confirm it is a member of the zinc-metallopeptidase family of enzymes. We show that this effector causes membrane blebbing at midcell, which suggests a distinct type of T6SS-mediated growth inhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Our study introduces a further effector family to the T6SS arsenal and demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells.
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Oct 2019
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I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
I24-Microfocus Macromolecular Crystallography
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M. Fleur
Sernee
,
Julie E.
Ralton
,
Tracy L.
Nero
,
Lukasz F.
Sobala
,
Joachim
Kloehn
,
Marcel A.
Vieira-lara
,
Simon A.
Cobbold
,
Lauren
Stanton
,
Douglas E. V.
Pires
,
Eric
Hanssen
,
Alexandra
Males
,
Tom
Ward
,
Laurence M.
Bastidas
,
Phillip L.
Van Der Peet
,
Michael W.
Parker
,
David B.
Ascher
,
Spencer J.
Williams
,
Gideon J.
Davies
,
Malcolm J.
Mcconville
Diamond Proposal Number(s):
[13587, 18598]
Open Access
Abstract: Parasitic protists belonging to the genus Leishmania synthesize the non-canonical carbohydrate reserve, mannogen, which is composed of β-1,2-mannan oligosaccharides. Here, we identify a class of dual-activity mannosyltransferase/phosphorylases (MTPs) that catalyze both the sugar nucleotide-dependent biosynthesis and phosphorolytic turnover of mannogen. Structural and phylogenic analysis shows that while the MTPs are structurally related to bacterial mannan phosphorylases, they constitute a distinct family of glycosyltransferases (GT108) that have likely been acquired by horizontal gene transfer from gram-positive bacteria. The seven MTPs catalyze the constitutive synthesis and turnover of mannogen. This metabolic rheostat protects obligate intracellular parasite stages from nutrient excess, and is essential for thermotolerance and parasite infectivity in the mammalian host. Our results suggest that the acquisition and expansion of the MTP family in Leishmania increased the metabolic flexibility of these protists and contributed to their capacity to colonize new host niches.
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Sep 2019
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I02-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
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Antoni G.
Wrobel
,
Zuzana
Kadlecova
,
Jan
Kamenicky
,
Ji-chun
Yang
,
Torsten
Herrmann
,
Bernard T.
Kelly
,
Airlie J.
Mccoy
,
Philip R.
Evans
,
Stephen
Martin
,
Stefan
Müller
,
Filip
Sroubek
,
David
Neuhaus
,
Stefan
Honing
,
David J.
Owen
Open Access
Abstract: Clathrin-mediated endocytosis (CME) is key to maintaining the transmembrane protein composition of cells’ limiting membranes. During mammalian CME, a reversible phosphorylation event occurs on Thr156 of the μ2 subunit of the main endocytic clathrin adaptor, AP2. We show that this phosphorylation event starts during clathrin-coated pit (CCP) initiation and increases throughout CCP lifetime. μ2Thr156 phosphorylation favors a new, cargo-bound conformation of AP2 and simultaneously creates a binding platform for the endocytic NECAP proteins but without significantly altering AP2’s cargo affinity in vitro. We describe the structural bases of both. NECAP arrival at CCPs parallels that of clathrin and increases with μ2Thr156 phosphorylation. In turn, NECAP recruits drivers of late stages of CCP formation, including SNX9, via a site distinct from where NECAP binds AP2. Disruption of the different modules of this phosphorylation-based temporal regulatory system results in CCP maturation being delayed and/or stalled, hence impairing global rates of CME.
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Aug 2019
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[12879, 24642]
Open Access
Abstract: Biometals such as iron, copper, potassium, and zinc are essential regulatory elements of several biological processes. The homeostasis of biometals is often affected in age-related pathologies. Notably, impaired iron metabolism has been linked to several neurodegenerative disorders. Autophagy, an intracellular degradative process dependent on the lysosomes, is involved in the regulation of ferritin and iron levels. Impaired autophagy has been associated with normal pathological aging, and neurodegeneration. Non-mammalian model organisms such as Drosophila have proven to be appropriate for the investigation of age-related pathologies. Here, we show that ferritin is expressed in adult Drosophila brain and that iron and holoferritin accumulate with aging. At whole-brain level we found no direct relationship between the accumulation of holoferritin and a deficit in autophagy in aged Drosophila brain. However, synchrotron X-ray spectromicroscopy revealed an additional spectral feature in the iron-richest region of autophagy-deficient fly brains, consistent with iron–sulfur. This potentially arises from iron–sulfur clusters associated with altered mitochondrial iron homeostasis.
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Jul 2019
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