Jérémie Piton , Florence Pojer , Soichi Wakatsuki , Cornelius Gati , Stewart T. Cole
{"title":"High resolution CryoEM structure of the ring-shaped virulence factor EspB from Mycobacterium tuberculosis","authors":"Jérémie Piton , Florence Pojer , Soichi Wakatsuki , Cornelius Gati , Stewart T. Cole","doi":"10.1016/j.yjsbx.2020.100029","DOIUrl":"https://doi.org/10.1016/j.yjsbx.2020.100029","url":null,"abstract":"<div><p>The EspB protein of <em>Mycobacterium tuberculosis</em> is a 60 kDa virulence factor, implicated in conjugation and exported by the ESX-1 system of which it may also be a component. Previous attempts to obtain high-resolution maps of EspB by cryo-electron microscopic examination of single particles have been thwarted by severe orientation bias of the particles. This was overcome by using detergent as a surfactant thereby allowing reconstruction of the EspB structure at 3.37 Å resolution. The final structure revealed the N-terminal domain of EspB to be organized as a cylindrical heptamer with dimensions of 90 Å x 90 Å and a central channel of 45 Å diameter whereas the C-terminal domain was unstructured. New atomic insight was obtained into the helical packing required for protomer interactions and the overall electrostatic potential. The external surface is electronegatively charged while the channel is lined with electropositive patches. EspB thus has many features of a pore-like transport protein that might allow the passage of an ESX-1 substrate such as the 35 Å diameter EsxA-EsxB heterodimer or B-form DNA consistent with its proposed role in DNA uptake.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100029"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72076018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingxu Guo , Alice Douangamath , Weixiao Song , Alun R. Coker , A.W. Edith Chan , Steve P. Wood , Jonathan B. Cooper , Efrat Resnick , Nir London , Frank von Delft
{"title":"In crystallo-screening for discovery of human norovirus 3C-like protease inhibitors","authors":"Jingxu Guo , Alice Douangamath , Weixiao Song , Alun R. Coker , A.W. Edith Chan , Steve P. Wood , Jonathan B. Cooper , Efrat Resnick , Nir London , Frank von Delft","doi":"10.1016/j.yjsbx.2020.100031","DOIUrl":"https://doi.org/10.1016/j.yjsbx.2020.100031","url":null,"abstract":"<div><p>Outbreaks of human epidemic nonbacterial gastroenteritis are mainly caused by noroviruses. Viral replication requires a 3C-like cysteine protease (3CL<sup>pro</sup>) which processes the 200 kDa viral polyprotein into six functional proteins. The 3CL<sup>pro</sup> has attracted much interest due to its potential as a target for antiviral drugs. A system for growing high-quality crystals of native Southampton norovirus 3CL<sup>pro</sup> (SV3CP) has been established, allowing the ligand-free crystal structure to be determined to 1.3 Å in a tetrameric state. This also allowed crystal-based fragment screening to be performed with various compound libraries, ultimately to guide drug discovery for SV3CP. A total of 19 fragments were found to bind to the protease out of the 844 which were screened. Two of the hits were located at the active site of SV3CP and showed good inhibitory activity in kinetic assays. Another 5 were found at the enzyme’s putative RNA-binding site and a further 11 were located in the symmetric central cavity of the tetramer.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100031"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72076019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J.L. Vilas , J. Oton , C. Messaoudi , R. Melero , P. Conesa , E. Ramirez-Aportela , J. Mota , M. Martinez , A. Jimenez , R. Marabini , J.M. Carazo , J. Vargas , C.O.S. Sorzano
{"title":"Measurement of local resolution in electron tomography","authors":"J.L. Vilas , J. Oton , C. Messaoudi , R. Melero , P. Conesa , E. Ramirez-Aportela , J. Mota , M. Martinez , A. Jimenez , R. Marabini , J.M. Carazo , J. Vargas , C.O.S. Sorzano","doi":"10.1016/j.yjsbx.2019.100016","DOIUrl":"10.1016/j.yjsbx.2019.100016","url":null,"abstract":"<div><p>Resolution (global and local) is one of the most reported metrics of quality measurement in Single Particle Analysis (SPA). However, in electron tomography, the situation is different and its computation is not straightforward. Typically, resolution estimation is global and, therefore, reduces the assessment of a whole tomogram to a single number. However, it is known that tomogram quality is spatially variant. Still, up to our knowledge, a method to estimate local quality metrics in tomography is lacking. This work introduces <em>MonoTomo</em>, a method developed to estimate locally in a tomogram the highest reliable frequency component, expressed as a form of local resolution. The fundamentals lie in a local analysis of the density map via monogenic signals, which, in analogy to <em>MonoRes</em>, allows for local estimations. Results with experimental data show that the local resolution range that MonoTomo casts agrees with reported resolution values for experimental data sets, with the advantage of providing a local estimation. A range of applications of <em>MonoTomo</em> are suggested for further exploration.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100016"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2019.100016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38137262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alina Kulakova , Sowmya Indrakumar , Pernille Sønderby , Lorenzo Gentiluomo , Werner Streicher , Dierk Roessner , Wolfgang Frieß , Günther H.J. Peters , Pernille Harris
{"title":"Small angle X-ray scattering and molecular dynamic simulations provide molecular insight for stability of recombinant human transferrin","authors":"Alina Kulakova , Sowmya Indrakumar , Pernille Sønderby , Lorenzo Gentiluomo , Werner Streicher , Dierk Roessner , Wolfgang Frieß , Günther H.J. Peters , Pernille Harris","doi":"10.1016/j.yjsbx.2019.100017","DOIUrl":"10.1016/j.yjsbx.2019.100017","url":null,"abstract":"<div><p>Transferrin is an attractive candidate for drug delivery due to its ability to cross the blood brain barrier. However, in order to be able to use it for therapeutic purposes, it is important to investigate how its stability depends on different formulation conditions. Combining high-throughput thermal and chemical denaturation studies with small angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations, it was possible to connect the stability of transferrin with its conformational changes. Lowering pH induces opening of the transferrin N-lobe, which results in a negative effect on the stability. Presence of NaCl or arginine at low pH enhances the opening and has a negative impact on the overall protein stability.</p></div><div><h3>Statement of Significance</h3><p>Protein-based therapeutics have become an essential part of medical treatment. They are highly specific, have high affinity and fewer off-target effects. However, stabilization of proteins is critical, time-consuming, and expensive, and it is not yet possible to predict the behavior of proteins under different conditions. The current work is focused on a molecular understanding of the stability of human serum transferrin; a protein which is abundant in blood serum, may pass the blood brain barrier and therefore with high potential in drug delivery. Combination of high throughput unfolding techniques and structural studies, using small angle X-ray scattering and molecular dynamic simulations, allows us to understand the behavior of transferrin on a molecular level.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100017"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2019.100017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38137264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yvonne Grobben, Joost C.M. Uitdehaag, Nicole Willemsen-Seegers, Werner W.A. Tabak, Jos de Man, Rogier C. Buijsman, Guido J.R. Zaman
{"title":"Structural insights into human Arginase-1 pH dependence and its inhibition by the small molecule inhibitor CB-1158","authors":"Yvonne Grobben, Joost C.M. Uitdehaag, Nicole Willemsen-Seegers, Werner W.A. Tabak, Jos de Man, Rogier C. Buijsman, Guido J.R. Zaman","doi":"10.1016/j.yjsbx.2019.100014","DOIUrl":"10.1016/j.yjsbx.2019.100014","url":null,"abstract":"<div><p>Arginase-1 is a manganese-dependent metalloenzyme that catalyzes the hydrolysis of L-arginine into L-ornithine and urea. Arginase-1 is abundantly expressed by tumor-infiltrating myeloid cells that promote tumor immunosuppression, which is relieved by inhibition of Arginase-1. We have characterized the potencies of the Arginase-1 reference inhibitors (2<em>S</em>)-2-amino-6-boronohexanoic acid (ABH) and <em>N</em><sup>ω</sup>-hydroxy-nor-L-arginine (nor-NOHA), and studied their pH-dependence and binding kinetics. To gain a better understanding of the structural changes underlying the high pH optimum of Arginase-1 and its pH-dependent inhibition, we determined the crystal structure of the human Arginase-1/ABH complex at pH 7.0 and 9.0. These structures revealed that at increased pH, the manganese cluster assumes a more symmetrical coordination structure, which presumably contributes to its increase in catalytic activity. Furthermore, we show that binding of ABH involves the presence of a sodium ion close to the manganese cluster. We also studied the investigational new drug CB-1158 (INCB001158). This inhibitor has a low-nanomolar potency at pH 7.4 and increases the thermal stability of Arginase-1 more than ABH and nor-NOHA. Moreover, CB-1158 displays slow association and dissociation kinetics at both pH 9.5 and 7.4, as indicated by surface plasmon resonance. The potent character of CB-1158 is presumably due to its increased rigidity compared to ABH as well as the formation of an additional hydrogen-bond network as observed by resolution of the Arginase-1/CB-1158 crystal structure.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100014"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2019.100014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38137863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anu Tyagi , Tofayel Ahmed , Jian Shi , Shashi Bhushan
{"title":"A complex between the Zika virion and the Fab of a broadly cross-reactive neutralizing monoclonal antibody revealed by cryo-EM and single particle analysis at 4.1 Å resolution","authors":"Anu Tyagi , Tofayel Ahmed , Jian Shi , Shashi Bhushan","doi":"10.1016/j.yjsbx.2020.100028","DOIUrl":"10.1016/j.yjsbx.2020.100028","url":null,"abstract":"<div><p>Zika virus (ZIKV) recently emerged as a major public health concern because it can cause fetal microcephaly and neurological disease such as the Guillain-Barré syndrome. A particularly potent class of broadly neutralizing antibodies (nAbs) targets a quaternary epitope located at the interface of two envelope proteins monomers, exposed at the surface of the mature virion. This “E-dimer-dependent epitope” (EDE), comprises the fusion loop of one monomer at the tip of domain II of E and a portion of the domains I and III of the adjacent monomer. Since this epitope largely overlaps with the binding site of the precursor membrane protein (prM) during Zika virion maturation, its molecular surface is evolutionary conserved in flaviviruses such as Dengue and Zika viruses, and can elicit antibodies that broadly neutralize various ZIKV strains. Here, we present a cryo-EM reconstruction at 4.1 Å resolution of the virion bound to the antigen binding fragment (Fab) of an antibody that targets this mutationally-constrained quaternary epitope. The Fab incompletely covers the surface of the virion as it does not bind next to its 5-fold icosahedral axes. The structure reveals details of the binding mode of this potent neutralizing class of antibodies and can inform the design of immunogens and vaccines targeting this conserved epitope.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100028"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38137190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Joseph Caesar , Cyril F. Reboul , Chiara Machello , Simon Kiesewetter , Molly L. Tang , Justin C. Deme , Steven Johnson , Dominika Elmlund , Susan M. Lea , Hans Elmlund
{"title":"SIMPLE 3.0. Stream single-particle cryo-EM analysis in real time","authors":"Joseph Caesar , Cyril F. Reboul , Chiara Machello , Simon Kiesewetter , Molly L. Tang , Justin C. Deme , Steven Johnson , Dominika Elmlund , Susan M. Lea , Hans Elmlund","doi":"10.1016/j.yjsbx.2020.100040","DOIUrl":"10.1016/j.yjsbx.2020.100040","url":null,"abstract":"<div><p>We here introduce the third major release of the SIMPLE (Single-particle IMage Processing Linux Engine) open-source software package for analysis of cryogenic transmission electron microscopy (cryo-EM) movies of single-particles (Single-Particle Analysis, SPA). Development of SIMPLE 3.0 has been focused on real-time data processing using minimal CPU computing resources to allow easy and cost-efficient scaling of processing as data rates escalate. Our stream SPA tool implements the steps of anisotropic motion correction and CTF estimation, rapid template-based particle identification and 2D clustering with automatic class rejection. SIMPLE 3.0 additionally features an easy-to-use web-based graphical user interface (GUI) that can be run on any device (workstation, laptop, tablet or phone) and supports a remote multi-user environment over the network. The new project-based execution model automatically records the executed workflow and represents it as a flow diagram in the GUI. This facilitates meta-data handling and greatly simplifies usage. Using SIMPLE 3.0, it is possible to automatically obtain a clean SP data set amenable to high-resolution 3D reconstruction directly upon completion of the data acquisition, without the need for extensive image processing post collection. Only minimal standard CPU computing resources are required to keep up with a rate of ∼300 Gatan K3 direct electron detector movies per hour. SIMPLE 3.0 is available for download from simplecryoem.com.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100040"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100040","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38351940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thomas Lemmin , David Kalbermatter , Daniel Harder , Philippe Plattet , Dimitrios Fotiadis
{"title":"Structures and dynamics of the novel S1/S2 protease cleavage site loop of the SARS-CoV-2 spike glycoprotein","authors":"Thomas Lemmin , David Kalbermatter , Daniel Harder , Philippe Plattet , Dimitrios Fotiadis","doi":"10.1016/j.yjsbx.2020.100038","DOIUrl":"10.1016/j.yjsbx.2020.100038","url":null,"abstract":"<div><p>At the end of 2019, a new highly virulent coronavirus known under the name SARS-CoV-2 emerged as a human pathogen. One key feature of SARS-CoV-2 is the presence of an enigmatic insertion in the spike glycoprotein gene representing a novel multibasic S1/S2 protease cleavage site. The proteolytic cleavage of the spike at this site is essential for viral entry into host cells. However, it has been systematically abrogated in structural studies in order to stabilize the spike in the prefusion state. In this study, multi-microsecond molecular dynamics simulations and <em>ab initio</em> modeling were leveraged to gain insights into the structures and dynamics of the loop containing the S1/S2 protease cleavage site. They unveiled distinct conformations, formations of short helices and interactions of the loop with neighboring glycans that could potentially regulate the accessibility of the cleavage site to proteases and its processing. In most conformations, this loop protrudes from the spike, thus representing an attractive SARS-CoV-2 specific therapeutic target.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100038"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38476957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reconstruction of Average Subtracted Tubular Regions (RASTR) enables structure determination of tubular filaments by cryo-EM","authors":"Peter S. Randolph , Scott M. Stagg","doi":"10.1016/j.yjsbx.2020.100023","DOIUrl":"10.1016/j.yjsbx.2020.100023","url":null,"abstract":"<div><p>As the field of electron microscopy advances, the increasing complexity of samples being produced demand more involved processing methods. In this study, we have developed a new processing method for generating 3D reconstructions of tubular structures. Tubular biomolecules are common throughout many cellular processes and are appealing targets for biophysical research. Processing of tubules with helical symmetry is relatively straightforward for electron microscopy if the helical parameters are known, but tubular structures that deviate from helical symmetry (asymmetrical components, local but no global order, etc) present myriad issues. Here we present a new processing technique called Reconstruction of Average Subtracted Tubular Regions (RASTR), which was developed to reconstruct tubular structures without applying symmetry. We explain the RASTR approach and quantify its performance using three examples: a simulated symmetrical tubular filament, a symmetrical tubular filament from cryo-EM data, and a membrane tubule coated with locally ordered but not globally ordered proteins.</p></div>","PeriodicalId":17238,"journal":{"name":"Journal of Structural Biology: X","volume":"4 ","pages":"Article 100023"},"PeriodicalIF":2.9,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.yjsbx.2020.100023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38137186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}