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	<title>bioRxiv Channel: Central Oxford Structural Molecular Imaging Centre </title>
	<link>https://biorxiv.org</link>
	<description>
	This feed contains articles for bioRxiv Channel "Central Oxford Structural Molecular Imaging Centre "
	</description>

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	<prism:publicationName>bioRxiv</prism:publicationName>
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	<title>bioRxiv</title>
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	<item rdf:about="https://biorxiv.org/cgi/content/short/647354v1?rss=1">
<title>
<![CDATA[
A novel inhibitor of complement C5 provides structural insights into activation 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/647354v1?rss=1"
</link>
<description><![CDATA[
The complement system is a crucial part of innate immune defences against invading pathogens. The blood-meal of the tick Rhipicephalus pulchellus lasts for days, and the tick must therefore rely on inhibitors to counter complement activation. We have identified a novel class of inhibitors from tick saliva, the CirpT family, and generated detailed structural data revealing their mechanism of action. We show direct binding of a CirpT to complement C5 and have determined the structure of the C5-CirpT complex by cryo-electron microscopy. This reveals an interaction with the peripheral macro globulin domain 4 (C5_MG4) of C5. To achieve higher resolution detail, the structure of the C5_MG4-CirpT complex was solved by X-ray crystallography (at 2.7 [A]). We thus present the novel fold of the CirpT protein family, and provide detailed mechanistic insights into its inhibitory function. Analysis of the binding interface reveals a novel mechanism of C5 inhibition, and provides information to expand our biological understanding of the activation of C5, and thus the terminal complement pathway.
]]></description>
<dc:creator>Reichhardt, M.</dc:creator>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Jore, M.</dc:creator>
<dc:creator>Tang, T.</dc:creator>
<dc:creator>Morgan, T.</dc:creator>
<dc:creator>Tebka, N.</dc:creator>
<dc:creator>Popitsch, N.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Lea, S. M.</dc:creator>
<dc:date>2019-05-23</dc:date>
<dc:identifier>doi:10.1101/647354</dc:identifier>
<dc:title><![CDATA[A novel inhibitor of complement C5 provides structural insights into activation]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2019-05-23</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/590273v1?rss=1">
<title>
<![CDATA[
The structure of an injectisome export gate demonstratesconservation of architecture in the core export gatebetween flagellar and virulence type three secretionsystems 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/590273v1?rss=1"
</link>
<description><![CDATA[
Export of proteins through type three secretion systems (T3SS) is critical for motility and virulence of many major bacterial pathogens. Proteins are exported though a genetically defined export gate complex consisting of three proteins. We have recently shown at 4.2 [A] that the flagellar complex of these three putative membrane proteins (FliPQR in flagellar systems, SctRST in virulence systems) assemble into an extra-membrane helical assembly that likely seeds correct assembly of the rod above. Here we present the structure of an equivalent complex from the more fragile Shigella virulence system at 3.5 [A] by cryo-electron microscopy. This higher resolution structure reveals further detail and confirms the prediction of structural conservation in this core complex. Analysis of particle heterogeneity also reveals details of how the SctS/FliQ subunits sequentially assemble in the complex.
]]></description>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Kuhlen, L.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Abrusci, P.</dc:creator>
<dc:creator>Lea, S. M.</dc:creator>
<dc:date>2019-03-27</dc:date>
<dc:identifier>doi:10.1101/590273</dc:identifier>
<dc:title><![CDATA[The structure of an injectisome export gate demonstratesconservation of architecture in the core export gatebetween flagellar and virulence type three secretionsystems]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2019-03-27</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/249128v1?rss=1">
<title>
<![CDATA[
Structure of the Core of the Type Three Secretion System ExportApparatus 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/249128v1?rss=1"
</link>
<description><![CDATA[
Export of proteins through type three secretion systems is critical for bacterial motility and virulence of many major bacterial pathogens. Three putative integral membrane proteins (FliP/FliQ/FliR) are suggested to form the core of an export gate in the inner membrane, but their structure, assembly and location within the final nanomachine remain unclear. We here present the structure of this complex at 4.2 [A] by cryo-electron microscopy. None of the subunits adopt canonical integral membrane protein topologies and common helix-turn-helix structural elements allow them to form a helical assembly with 5:4:1 stoichiometry. Fitting of the structure into reconstructions of intact secretion systems localize the export gate as a core component of the periplasmic portion of the machinery, and cross-linking experiments confirm this observation. This study thereby identifies the export gate as a key element of the secretion channel and implies that it primes the helical architecture of the components assembling downstream.nnOne Sentence SummaryThe core of the T3SS export gate forms a supra-membrane helical assembly
]]></description>
<dc:creator>Kuhlen, L.</dc:creator>
<dc:creator>Abrusci, P.</dc:creator>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Gault, J.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Caesar, J.</dc:creator>
<dc:creator>Dietsche, T.</dc:creator>
<dc:creator>Mebrhatu, M. T.</dc:creator>
<dc:creator>Ganief, T.</dc:creator>
<dc:creator>Macek, B.</dc:creator>
<dc:creator>Wagner, S.</dc:creator>
<dc:creator>Robinson, C. V.</dc:creator>
<dc:creator>Lea, S. M.</dc:creator>
<dc:date>2018-01-17</dc:date>
<dc:identifier>doi:10.1101/249128</dc:identifier>
<dc:title><![CDATA[Structure of the Core of the Type Three Secretion System ExportApparatus]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2018-01-17</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/579128v1?rss=1">
<title>
<![CDATA[
Rod-shaped tricalbins contribute to PM asymmetry at curved ER-PM contact sites 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/579128v1?rss=1"
</link>
<description><![CDATA[
Lipid flow between cellular organelles occurs via membrane contact sites that form dynamic conduits. Extended-synaptotagmins, known as tricalbins in yeast, mediate lipid transfer between the endoplasmic reticulum (ER) and plasma membrane (PM). How these proteins regulate the membrane architecture to transport lipids across the aqueous space between bilayers remains unknown. Using correlative microscopy, electron cryo-tomography and high-throughput genetics we address this interplay of architecture and function in budding yeast. We find that ER-PM contacts are diverse in protein composition and membrane morphology, not in intermembrane distance. In situ cryo-EM of tricalbins reveals their molecular organisation that suggests an unexpected structural framework for lipid transfer. Genetic analysis identifies functional redundancies, both for tricalbin domains and cellular lipid routes, and points to tricalbin function in maintenance of PM asymmetry. These results uncover a modularity of molecular and structural functions of tricalbins, and of their roles within the network of cellular lipid fluxes.
]]></description>
<dc:creator>Hoffmann, P. C.</dc:creator>
<dc:creator>Bharat, T. A. M.</dc:creator>
<dc:creator>Wozny, M. R.</dc:creator>
<dc:creator>Miller, E. A.</dc:creator>
<dc:creator>Kukulski, W.</dc:creator>
<dc:date>2019-03-15</dc:date>
<dc:identifier>doi:10.1101/579128</dc:identifier>
<dc:title><![CDATA[Rod-shaped tricalbins contribute to PM asymmetry at curved ER-PM contact sites]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2019-03-15</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/686782v1?rss=1">
<title>
<![CDATA[
The flagellar substrate specificity switch protein FlhB assembles onto the extra-membrane export gate to regulate type three secretion 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/686782v1?rss=1"
</link>
<description><![CDATA[
Export of proteins through type three secretion systems (T3SS) is critical for motility and virulence of many major bacterial pathogens. Proteins are transported through an export gate complex consisting of three proteins (FliPQR in flagellar systems, SctRST in virulence systems) that were initially annotated as membrane proteins, but which we have recently shown assemble into an extra-membranous helical assembly. A fourth putative membrane protein (FlhB/SctU) is essential to the export process, and also functions to "switch" secretion substrate specificity once the growing hook/needle structures reach their determined length. Here we present the structure of an export gate containing the switch protein from a Vibrio polar flagellar system at 3.2 [A] resolution by cryo-electron microscopy. The structure reveals that the FlhB/SctU further extends the helical export gate assembly with its four putative transmembrane helices adopting an out-of-membrane location, wrapped around the other export gate components at the base of the structure. The unusual topology of the switch protein helices creates a loop that wraps around the bottom of the closed export gate complex. Structure-informed mutagenesis suggests that this loop is critical in gating secretion and we propose that a series of conformational changes in the type 3 secretion system trigger opening of the export gate through the interactions between FlhB/SctU and FliPQR/SctRST.
]]></description>
<dc:creator>Kuhlen, L.</dc:creator>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Zeitler, A.</dc:creator>
<dc:creator>Baurle, S.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Debo, R.</dc:creator>
<dc:creator>Fisher, J.</dc:creator>
<dc:creator>Wagner, S.</dc:creator>
<dc:creator>Lea, S.</dc:creator>
<dc:date>2019-07-04</dc:date>
<dc:identifier>doi:10.1101/686782</dc:identifier>
<dc:title><![CDATA[The flagellar substrate specificity switch protein FlhB assembles onto the extra-membrane export gate to regulate type three secretion]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2019-07-04</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/718072v1?rss=1">
<title>
<![CDATA[
Structure of the bacterial flagellar rotor MS-ring: a minimum inventory/maximum diversity system 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/718072v1?rss=1"
</link>
<description><![CDATA[
The bacterial flagellum is a complex, self-assembling, nanomachine that confers motility on the cell. Despite great variation across species, all flagella are ultimately constructed from a helical propellor attached to a motor embedded in the inner membrane. The motor consists of a series of stator units surrounding a central rotor made up of two ring complexes, the MS-ring and the C-ring. Despite many studies, high resolution structural information is still completely lacking for the MS-ring of the rotor, and proposed mismatches in stoichiometry between the two rings have long provided a source of confusion for the field. We here present structures of the Salmonella MS-ring, revealing an unprecedented level of inter- and intra-chain symmetry variation that provides a structural explanation for the ability of the MS-ring to function as a complex and elegant interface between the two main functions of the flagellum, protein secretion and rotation.
]]></description>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Fong, Y. H.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Furlong, E.</dc:creator>
<dc:creator>Kuhlen, L.</dc:creator>
<dc:creator>Lea, S.</dc:creator>
<dc:date>2019-07-30</dc:date>
<dc:identifier>doi:10.1101/718072</dc:identifier>
<dc:title><![CDATA[Structure of the bacterial flagellar rotor MS-ring: a minimum inventory/maximum diversity system]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2019-07-30</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/2020.05.11.089193v1?rss=1">
<title>
<![CDATA[
Structure of a proton-powered molecular motor that drives protein transport and gliding motility 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/2020.05.11.089193v1?rss=1"
</link>
<description><![CDATA[
Ion-driven motors are rare in biology. The archetypes of the three classes identified to date are ATP synthase, the bacterial flagellar motor, and a proton-driven motor that powers gliding motility and protein secretion in Bacteroidetes bacteria. Whilst the molecular mechanism of ATP synthase is now well understood, structural information is lacking for the other two classes of motor. Here we present the structure of the Bacteroidetes gliding motility motor determined by cryo-electron microscopy. The motor is an asymmetric inner membrane protein complex in which the single transmembrane helices of two periplasm-spanning GldM proteins are positioned within a ring of five GldL proteins. Combining mutagenesis and single-molecule tracking, we identify protonatable amino acid residues within the transmembrane domain of the complex that are important for motor function. Our data imply a mechanism in which proton flow leads the periplasm-spanning GldM dimer to rotate with respect to the intra-membrane GldL ring to drive processes at the bacterial outer membrane. This work provides a molecular basis for understanding how the gliding motility motor is able to transduce the energy of the inner membrane protonmotive force across the bacterial cell envelope.
]]></description>
<dc:creator>Hennell-James, R.</dc:creator>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Kjaer, A.</dc:creator>
<dc:creator>Alcock, F.</dc:creator>
<dc:creator>Silale, A.</dc:creator>
<dc:creator>Lauber, F.</dc:creator>
<dc:creator>Berks, B.</dc:creator>
<dc:creator>Lea, S. M.</dc:creator>
<dc:date>2020-05-14</dc:date>
<dc:identifier>doi:10.1101/2020.05.11.089193</dc:identifier>
<dc:title><![CDATA[Structure of a proton-powered molecular motor that drives protein transport and gliding motility]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2020-05-14</prism:publicationDate>
<prism:section></prism:section>
</item>
<item rdf:about="https://biorxiv.org/cgi/content/short/2020.05.12.089201v1?rss=1">
<title>
<![CDATA[
Structures of the stator complex that drives rotation of the bacterial flagellum 
]]>
</title>
<link>
https://biorxiv.org/cgi/content/short/2020.05.12.089201v1?rss=1"
</link>
<description><![CDATA[
The bacterial flagellum is the proto-typical protein nanomachine and comprises a rotating helical propeller attached to a membrane-embedded motor complex1. The motor consists of a central rotor surround by stator units that couple ion flow across the cytoplasmic membrane to torque generation. Here we present the structures of stator complexes from multiple bacterial species, allowing interpretation of the extensive body of data on stator mechanism. The structures reveal an unexpected asymmetric A5B2 subunit assembly in which the five A subunits enclose the two B subunits. Comparison to novel structures of other ion-driven motors indicates that this A5B2 architecture is fundamental to bacterial systems that couple energy from ion-flow to generate mechanical work at a distance, and suggests that such events involve rotation in the motor structures.
]]></description>
<dc:creator>Deme, J.</dc:creator>
<dc:creator>Johnson, S.</dc:creator>
<dc:creator>Vickery, O.</dc:creator>
<dc:creator>Muellbauer, A.</dc:creator>
<dc:creator>Monkhouse, H.</dc:creator>
<dc:creator>Griffiths, T.</dc:creator>
<dc:creator>Hennell-James, R.</dc:creator>
<dc:creator>Berks, B.</dc:creator>
<dc:creator>Coulton, J.</dc:creator>
<dc:creator>Stansfeld, P. J.</dc:creator>
<dc:creator>Lea, S. M.</dc:creator>
<dc:date>2020-05-13</dc:date>
<dc:identifier>doi:10.1101/2020.05.12.089201</dc:identifier>
<dc:title><![CDATA[Structures of the stator complex that drives rotation of the bacterial flagellum]]></dc:title>
<dc:publisher>Cold Spring Harbor Laboratory Press</dc:publisher>
<prism:publicationDate>2020-05-13</prism:publicationDate>
<prism:section></prism:section>
</item>
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