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Shrestha P, Yang D, Ward A, Shih WM, Wong WP. Mapping Single-Molecule Protein Complexes in 3D with DNA Nanoswitch Calipers. J Am Chem Soc 2023; 145:27916-27921. [PMID: 38096567 PMCID: PMC10755700 DOI: 10.1021/jacs.3c10262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/11/2023] [Accepted: 12/12/2023] [Indexed: 12/26/2023]
Abstract
The ability to accurately map the 3D geometry of single-molecule complexes in trace samples is a challenging goal that would lead to new insights into molecular mechanics and provide an approach for single-molecule structural proteomics. To enable this, we have developed a high-resolution force spectroscopy method capable of measuring multiple distances between labeled sites in natively folded protein complexes. Our approach combines reconfigurable nanoscale devices, we call DNA nanoswitch calipers, with a force-based barcoding system to distinguish each measurement location. We demonstrate our approach by reconstructing the tetrahedral geometry of biotin-binding sites in natively folded streptavidin, with 1.5-2.5 Å agreement with previously reported structures.
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Affiliation(s)
- Prakash Shrestha
- Program
in Cellular and Molecular Medicine, Boston
Children’s Hospital, Boston, Massachusetts 02115, United States
- Wyss
Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02215, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Darren Yang
- Program
in Cellular and Molecular Medicine, Boston
Children’s Hospital, Boston, Massachusetts 02115, United States
- Wyss
Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02215, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Andrew Ward
- Program
in Cellular and Molecular Medicine, Boston
Children’s Hospital, Boston, Massachusetts 02115, United States
- Wyss
Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02215, United States
| | - William M. Shih
- Wyss
Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02215, United States
- Department
of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Wesley P. Wong
- Program
in Cellular and Molecular Medicine, Boston
Children’s Hospital, Boston, Massachusetts 02115, United States
- Wyss
Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02215, United States
- Department
of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, United States
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2
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Shrestha P, Yang D, Shih WM, Wong WP. Mapping Single-molecule Protein Complexes in 3D with DNA Nanoswitch Calipers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548386. [PMID: 37502860 PMCID: PMC10369884 DOI: 10.1101/2023.07.10.548386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The ability to accurately map the 3D geometry of single-molecule complexes in trace samples would lead to new insights into molecular mechanics and provide an approach for single-molecule structural proteomics. To enable this, we have developed a high-resolution force-spectroscopy method capable of measuring multiple distances between labeled sites in natively folded protein complexes. Our approach combines reconfigurable nanoscale devices we call DNA Nanoswitch Calipers, which we have previously introduced, with a force-based barcoding system to distinguish each measurement location. We demonstrate our approach by reconstructing the tetrahedral geometry of biotin-binding sites in natively folded streptavidin, with 1.5-2.5 Å agreement to previously reported structures.
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3
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Lin YY, Brouns T, Kolbeck PJ, Vanderlinden W, Lipfert J. High-yield ligation-free assembly of DNA constructs with nucleosome positioning sequence repeats for single-molecule manipulation assays. J Biol Chem 2023; 299:104874. [PMID: 37257819 PMCID: PMC10404619 DOI: 10.1016/j.jbc.2023.104874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/08/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
Force and torque spectroscopy have provided unprecedented insights into the mechanical properties, conformational transitions, and dynamics of DNA and DNA-protein complexes, notably nucleosomes. Reliable single-molecule manipulation measurements require, however, specific and stable attachment chemistries to tether the molecules of interest. Here, we present a functionalization strategy for DNA that enables high-yield production of constructs for torsionally constrained and very stable attachment. The method is based on two subsequent PCRs: first ∼380 bp long DNA strands are generated that contain multiple labels, which are used as "megaprimers" in a second PCR to generate ∼kbp long double-stranded DNA constructs with multiple labels at the respective ends. To achieve high-force stability, we use dibenzocyclooctyne-based click chemistry for covalent attachment to the surface and biotin-streptavidin coupling to the bead. The resulting tethers are torsionally constrained and extremely stable under load, with an average lifetime of 70 ± 3 h at 45 pN. The high yield of the approach enables nucleosome reconstitution by salt dialysis on the functionalized DNA, and we demonstrate proof-of-concept measurements on nucleosome assembly statistics and inner turn unwrapping under force. We anticipate that our approach will facilitate a range of studies of DNA interactions and nucleoprotein complexes under forces and torques.
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Affiliation(s)
- Yi-Yun Lin
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Tine Brouns
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Division of Molecular Imaging and Photonics, KU Leuven, Leuven, Belgium
| | - Pauline J Kolbeck
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands
| | - Willem Vanderlinden
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
| | - Jan Lipfert
- Department of Physics and Center for NanoScience (CeNS), LMU Munich, Munich, Germany; Soft Condensed Matter and Biophysics, Department of Physics and Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
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4
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Scietti L, Forneris F. Modeling of Protein Complexes. Methods Mol Biol 2023; 2627:349-371. [PMID: 36959458 DOI: 10.1007/978-1-0716-2974-1_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The recent advances in structural biology, combined with continuously increasing computational capabilities and development of advanced softwares, have drastically simplified the workflow for protein homology modeling. Modeling of individual proteins is nowadays quick and straightforward for a large variety of protein targets, thanks to guided pipelines relying on advanced computational tools and user-friendly interfaces, which have extended and promoted the use of modeling also to scientists not focusing on molecular structures of proteins. Nevertheless, construction of models of multi-protein complexes remains quite challenging for the non-experts, often due to the usage of specific procedures depending on the system under investigation and the need for experimental validation approaches to strengthen the generated output.In this chapter, we provide a brief overview of the approaches enabling generation of multi-protein complex models starting from homology models of individual protein components. Using real-life examples, we include two examples to guide the reader in the generation of homomeric and heteromeric protein models.
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Affiliation(s)
- Luigi Scietti
- Department of Biology and Biotechnology, The Armenise-Harvard Laboratory of Structural Biology, University of Pavia, Pavia, Italy.
| | - Federico Forneris
- Department of Biology and Biotechnology, The Armenise-Harvard Laboratory of Structural Biology, University of Pavia, Pavia, Italy.
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5
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Karasawa A, Andi B, Fuchs MR, Shi W, McSweeney S, Hendrickson WA, Liu Q. Multi-crystal native-SAD phasing at 5 keV with a helium environment. IUCRJ 2022; 9:768-777. [PMID: 36381147 PMCID: PMC9634608 DOI: 10.1107/s205225252200971x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
De novo structure determination from single-wavelength anomalous diffraction using native sulfur or phospho-rus in biomolecules (native-SAD) is an appealing method to mitigate the labor-intensive production of heavy-atom derivatives and seleno-methio-nyl substitutions. The native-SAD method is particularly attractive for membrane proteins, which are difficult to produce and often recalcitrant to grow into decent-sized crystals. Native-SAD uses lower-energy X-rays to enhance anomalous signals from sulfur or phospho-rus. However, at lower energies, the scattering and absorption of air contribute to the background noise, reduce the signals and are thus adverse to native-SAD phasing. We have previously demonstrated native-SAD phasing at an energy of 5 keV in air at the NSLS-II FMX beamline. Here, the use of a helium path developed to reduce both the noise from background scattering and the air absorption of the diffracted X-ray beam are described. The helium path was used for collection of anomalous diffraction data at 5 keV for two proteins: thaumatin and the membrane protein TehA. Although anomalous signals from each individual crystal are very weak, robust anomalous signals are obtained from data assembled from micrometre-sized crystals. The thaumatin structure was determined from 15 microcrystals and the TehA structure from 18 microcrystals. These results demonstrate the usefulness of a helium environment in support of native-SAD phasing at 5 keV.
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Affiliation(s)
- Akira Karasawa
- Center on Membrane Protein Production and Analysis, New York Structural Biology Center, New York, NY 10027, USA
| | - Babak Andi
- Photon Sciences, NSLS-II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Martin R. Fuchs
- Photon Sciences, NSLS-II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Wuxian Shi
- Photon Sciences, NSLS-II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Sean McSweeney
- Photon Sciences, NSLS-II, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Wayne A. Hendrickson
- Center on Membrane Protein Production and Analysis, New York Structural Biology Center, New York, NY 10027, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, USA
| | - Qun Liu
- Photon Sciences, NSLS-II, Brookhaven National Laboratory, Upton, NY 11973, USA
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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6
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Greisman JB, Dalton KM, Sheehan CJ, Klureza MA, Kurinov I, Hekstra DR. Native SAD phasing at room temperature. Acta Crystallogr D Struct Biol 2022; 78:986-996. [PMID: 35916223 PMCID: PMC9344477 DOI: 10.1107/s2059798322006799] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 07/01/2022] [Indexed: 11/10/2022] Open
Abstract
Single-wavelength anomalous diffraction (SAD) is a routine method for overcoming the phase problem when solving macromolecular structures. This technique requires the accurate measurement of intensities to determine differences between Bijvoet pairs. Although SAD experiments are commonly conducted at cryogenic temperatures to mitigate the effects of radiation damage, such temperatures can alter the conformational ensemble of the protein and may impede the merging of data from multiple crystals due to non-uniform freezing. Here, a strategy is presented to obtain high-quality data from room-temperature, single-crystal experiments. To illustrate the strengths of this approach, native SAD phasing at 6.55 keV was used to solve four structures of three model systems at 295 K. The resulting data sets allow automatic phasing and model building, and reveal alternate conformations that reflect the structure of proteins at room temperature.
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Affiliation(s)
- Jack B. Greisman
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, Massachusetts, USA
| | - Kevin M. Dalton
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, Massachusetts, USA
| | - Candice J. Sheehan
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, Massachusetts, USA
| | - Margaret A. Klureza
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts, USA
| | - Igor Kurinov
- NE-CAT, Department of Chemistry and Chemical Biology, Cornell University, 9700 South Cass Avenue, Argonne, Illinois, USA
| | - Doeke R. Hekstra
- Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, Massachusetts, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 52 Oxford Street, Cambridge, Massachusetts, USA
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7
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Bhatia I, Yadav S, Biswal BK. Identification, structure determination and analysis of Mycobacterium smegmatis acyl-carrier protein synthase (AcpS) crystallized serendipitously. Acta Crystallogr F Struct Biol Commun 2022; 78:252-264. [PMID: 35787552 PMCID: PMC9254898 DOI: 10.1107/s2053230x22005738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/26/2022] [Indexed: 11/11/2022] Open
Abstract
The unintended crystallization of proteins which generally originate from the expression host instead of the target recombinant proteins is periodically reported. Despite the massive technological advances in the field, assigning a structural model to the corresponding diffraction data is not a trivial task. Here, the structure of acyl-carrier protein synthase (AcpS) from Mycobacterium smegmatis (msAcpS), which crystallized inadvertently in an experimental setup to grow crystals of a Mycobacterium tuberculosis protein using M. smegmatis as an expression system, is reported. After numerous unsuccessful attempts to solve the structure of the target protein by the molecular-replacement method no convincing solutions were obtained, indicating that the diffraction data may correspond to a crystal of an artifactual protein, which was finally identified by the Sequence-Independent Molecular replacement Based on Available Databases (SIMBAD) server. The msAcpS structure was solved at 2.27 Å resolution and structural analysis showed an overall conserved fold. msAcpS formed a trimeric structure similar to those of other reported structures of AcpS from various organisms; however, the residues involved in trimer formation are not strictly conserved. An unrelated metal ion (Ni2+), which was possibly incorporated during protein purification, was observed in the proximity of His49 and His116. Structural and sequence differences were observed in the loop connecting the α3 and α4 helices that is responsible for the open and closed conformations of the enzyme. Moreover, the structural analysis of msAcpS augments the current understanding of this enzyme, which plays a crucial role in the functional activation of acyl-carrier proteins in the fatty-acid biosynthesis pathway.
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Affiliation(s)
- Indu Bhatia
- Structural and Functional Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Savita Yadav
- Structural and Functional Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
| | - Bichitra K. Biswal
- Structural and Functional Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
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8
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Monitoring protein conformational changes using fluorescent nanoantennas. Nat Methods 2022; 19:71-80. [PMID: 34969985 DOI: 10.1038/s41592-021-01355-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 11/10/2021] [Indexed: 01/03/2023]
Abstract
Understanding the relationship between protein structural dynamics and function is crucial for both basic research and biotechnology. However, methods for studying the fast dynamics of structural changes are limited. Here, we introduce fluorescent nanoantennas as a spectroscopic technique to sense and report protein conformational changes through noncovalent dye-protein interactions. Using experiments and molecular simulations, we detect and characterize five distinct conformational states of intestinal alkaline phosphatase, including the transient enzyme-substrate complex. We also explored the universality of the nanoantenna strategy with another model protein, Protein G and its interaction with antibodies, and demonstrated a rapid screening strategy to identify efficient nanoantennas. These versatile nanoantennas can be used with diverse dyes to monitor small and large conformational changes, suggesting that they could be used to characterize diverse protein movements or in high-throughput screening applications.
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9
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Guimarães BG, Golinelli-Pimpaneau B. De novo crystal structure determination of double stranded RNA binding domain using only the sulfur anomalous diffraction in SAD phasing. Curr Res Struct Biol 2021; 3:112-120. [PMID: 34235491 PMCID: PMC8244422 DOI: 10.1016/j.crstbi.2021.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 10/25/2022] Open
Abstract
Single-wavelength anomalous dispersion (SAD)-phasing using sulfur as the unique anomalous scatterer is a powerful method to solve the phase problem in protein crystallography. However, it is not yet widely used by non-expert crystallographers. We report here the structure determination of the double stranded RNA binding domain of human dihydrouridine synthase using the sulfur-SAD method and highly redundant data collected at 1.8 Å ("off-edge"), at which the estimated overall anomalous signal was 1.08%. High multiplicity data were collected on a single crystal rotated along the ϕ or ω axis at different κ angles, with the primary beam intensity being attenuated from 50% to 95%, compared to data collection at 0.98 Å, to reduce radiation damage. SHELXD succeeded to locate 14 out 15 sulfur sites only using the data sets recorded with highest beam attenuation, which provided phases sufficient for structure solving. In an attempt to stimulate the use of sulfur-SAD phasing by a broader community of crystallographers, we describe our experimental strategy together with a compilation of previous successful cases, suggesting that sulfur-SAD phasing should be attempted for determining the de novo structure of any protein with average sulfur content diffracting better than 3 Å resolution.
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Affiliation(s)
| | - Béatrice Golinelli-Pimpaneau
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
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Gruber S, Löf A, Sedlak SM, Benoit M, Gaub HE, Lipfert J. Designed anchoring geometries determine lifetimes of biotin-streptavidin bonds under constant load and enable ultra-stable coupling. NANOSCALE 2020; 12:21131-21137. [PMID: 33079117 DOI: 10.1039/d0nr03665j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The small molecule biotin and the homotetrameric protein streptavidin (SA) form a stable and robust complex that plays a pivotal role in many biotechnological and medical applications. In particular, the SA-biotin linkage is frequently used in single-molecule force spectroscopy (SMFS) experiments. Recent data suggest that SA-biotin bonds show strong directional dependence and a broad range of multi-exponential lifetimes under load. Here, we investigate engineered SA variants with different valencies and a unique tethering point under constant forces using a magnetic tweezers assay. We observed orders-of-magnitude differences in the lifetimes under force, which we attribute to the distinct force-loading geometries in the different SA variants. Lifetimes showed exponential dependencies on force, with extrapolated lifetimes at zero force that are similar for the different SA variants and agree with parameters determined from constant-speed dynamic SMFS experiments. We identified an especially long-lived tethering geometry that will facilitate ultra-stable SMFS experiments.
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Affiliation(s)
- Sophia Gruber
- Department of Physics and Center for NanoScience, LMU Munich, Germany.
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11
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Abstract
The complex of the small molecule biotin and the homotetrameric protein streptavidin is key to a broad range of biotechnological applications. Therefore, the behavior of this extraordinarily high-affinity interaction under mechanical force is intensively studied by single-molecule force spectroscopy. Recently, steered molecular dynamics simulations have identified a low force pathway for the dissociation of biotin from streptavidin, which involves partial unfolding of the N-terminal β-sheet structure of monovalent streptavidin's functional subunit. Based on these results, we now introduced two mutations (T18C,A33C) in the functional subunit of monovalent streptavidin to establish a switchable connection (disulfide bridge) between the first two β-strands to prevent this unfolding. In atomic force microscopy-based single-molecule force spectroscopy experiments, we observed unbinding forces of about 350 pN (at a force-loading rate of 10 nN s-1) for pulling a single biotin out of an N-terminally anchored monovalent streptavidin binding pocket - about 1.5-fold higher compared with what has been reported for N-terminal force loading of native monovalent streptavidin. Upon addition of a reducing agent, the unbinding forces dropped back to 200 pN, as the disulfide bridge was destroyed. Switching from reducing to oxidizing buffer conditions, the inverse effect was observed. Our work illustrates how the mechanics of a receptor-ligand system can be tuned by engineering the receptor protein far off the ligand-binding pocket.
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Affiliation(s)
- Leonard C Schendel
- Lehrstuhl für Angewandte Physik and Center for NanoScience, Ludwig-Maximilians-Universität München, Amalienstr. 54, 80799 Munich, Germany.
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12
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Coulibaly F. Polyhedra, spindles, phage nucleus and pyramids: Structural biology of viral superstructures. Adv Virus Res 2019; 105:275-335. [PMID: 31522707 DOI: 10.1016/bs.aivir.2019.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Viral infection causes comprehensive rearrangements of the cell that reflect as much host defense mechanisms as virus-induced structures assembled to facilitate infection. Regardless of their pro- or antiviral role, large intracellular structures are readily detectable by microscopy and often provide a signature characteristic of a specific viral infection. The structural features and localization of these assemblies have thus been commonly used for the diagnostic and classification of viruses since the early days of virology. More recently, characterization of viral superstructures using molecular and structural approaches have revealed very diverse organizations and roles, ranging from dynamic viral factories behaving like liquid organelles to ultra-stable crystals embedding and protecting virions. This chapter reviews the structures, functions and biotechnological applications of virus-induced superstructures with a focus on assemblies that have a regular organization, for which detailed structural descriptions are available. Examples span viruses infecting all domains of life including the assembly of virions into crystalline arrays in eukaryotic and bacterial viruses, nucleus-like compartments involved in the replication of large bacteriophages, and pyramid-like structures mediating the egress of archaeal viruses. Among these superstructures, high-resolution structures are available for crystalline objects produced by insect viruses: viral polyhedra which function as the infectious form of occluded viruses, and spindles which are potent virulence factors of entomopoxviruses. In turn, some of these highly symmetrical objects have been used to develop and validate advanced structural approaches, pushing the boundary of structural biology.
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Affiliation(s)
- Fasséli Coulibaly
- Infection & Immunity Program, Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
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13
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Hohmann U, Hothorn M. Crystal structure of the leucine-rich repeat ectodomain of the plant immune receptor kinase SOBIR1. Acta Crystallogr D Struct Biol 2019; 75:488-497. [PMID: 31063151 PMCID: PMC6503760 DOI: 10.1107/s2059798319005291] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/16/2019] [Indexed: 01/17/2023] Open
Abstract
Plant-unique membrane receptor kinases with leucine-rich repeat (LRR) extracellular domains are key regulators of development and immune responses. Here, the 1.55 Å resolution crystal structure of the immune receptor kinase SOBIR1 from Arabidopsis is presented. The ectodomain structure reveals the presence of five LRRs sandwiched between noncanonical capping domains. The disulfide-bond-stabilized N-terminal cap harbours an unusual β-hairpin structure. The C-terminal cap features a highly positively charged linear motif which was found to be largely disordered in this structure. Size-exclusion chromatography and right-angle light-scattering experiments suggest that SOBIR1 is a monomer in solution. The protruding β-hairpin, a set of highly conserved basic residues at the inner surface of the SOBIR LRR domain and the presence of a genetic missense allele in LRR2 together suggest that the SOBIR1 ectodomain may mediate protein-protein interaction in plant immune signalling.
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Affiliation(s)
- Ulrich Hohmann
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Michael Hothorn
- Structural Plant Biology Laboratory, Department of Botany and Plant Biology, University of Geneva, 1211 Geneva, Switzerland
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