1
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Chen G, Wang Y, Zheng Z, Jiang W, Leppert A, Zhong X, Belorusova A, Siegal G, Jegerschöld C, Koeck PJB, Abelein A, Hebert H, Knight SD, Johansson J. Molecular basis for different substrate-binding sites and chaperone functions of the BRICHOS domain. Protein Sci 2024; 33:e5063. [PMID: 38864729 PMCID: PMC11168071 DOI: 10.1002/pro.5063] [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: 02/06/2024] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 06/13/2024]
Abstract
Proteins can misfold into fibrillar or amorphous aggregates and molecular chaperones act as crucial guardians against these undesirable processes. The BRICHOS chaperone domain, found in several otherwise unrelated proproteins that contain amyloidogenic regions, effectively inhibits amyloid formation and toxicity but can in some cases also prevent non-fibrillar, amorphous protein aggregation. Here, we elucidate the molecular basis behind the multifaceted chaperone activities of the BRICHOS domain from the Bri2 proprotein. High-confidence AlphaFold2 and RoseTTAFold predictions suggest that the intramolecular amyloidogenic region (Bri23) is part of the hydrophobic core of the proprotein, where it occupies the proposed amyloid binding site, explaining the markedly reduced ability of the proprotein to prevent an exogenous amyloidogenic peptide from aggregating. However, the BRICHOS-Bri23 complex maintains its ability to form large polydisperse oligomers that prevent amorphous protein aggregation. A cryo-EM-derived model of the Bri2 BRICHOS oligomer is compatible with surface-exposed hydrophobic motifs that get exposed and come together during oligomerization, explaining its effects against amorphous aggregation. These findings provide a molecular basis for the BRICHOS chaperone domain function, where distinct surfaces are employed against different forms of protein aggregation.
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Affiliation(s)
- Gefei Chen
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- Department of Cell and Molecular BiologyUppsala UniversityUppsalaSweden
| | - Yu Wang
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- College of Wildlife and Protected Area, Northeast Forestry UniversityHarbinChina
| | - Zihan Zheng
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- Department of PharmacologyXi'an Jiaotong UniversityXi'anChina
| | - Wangshu Jiang
- Department of Cell and Molecular BiologyUppsala UniversityUppsalaSweden
| | - Axel Leppert
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- Present address:
Department of Microbiology, Tumour and Cell BiologyKarolinska InstitutetSolnaSweden
| | - Xueying Zhong
- Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and HealthKTH Royal Institute of TechnologyHuddingeSweden
| | | | | | - Caroline Jegerschöld
- Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and HealthKTH Royal Institute of TechnologyHuddingeSweden
| | - Philip J. B. Koeck
- Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and HealthKTH Royal Institute of TechnologyHuddingeSweden
| | - Axel Abelein
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
| | - Hans Hebert
- Department of Biomedical Engineering and Health Systems, School of Engineering Sciences in Chemistry, Biotechnology and HealthKTH Royal Institute of TechnologyHuddingeSweden
| | - Stefan D. Knight
- Department of Cell and Molecular BiologyUppsala UniversityUppsalaSweden
| | - Jan Johansson
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
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2
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Odorčić I, Hamed MB, Lismont S, Chávez-Gutiérrez L, Efremov RG. Apo and Aβ46-bound γ-secretase structures provide insights into amyloid-β processing by the APH-1B isoform. Nat Commun 2024; 15:4479. [PMID: 38802343 PMCID: PMC11130327 DOI: 10.1038/s41467-024-48776-2] [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: 08/29/2023] [Accepted: 05/07/2024] [Indexed: 05/29/2024] Open
Abstract
Deposition of amyloid-β (Aβ) peptides in the brain is a hallmark of Alzheimer's disease. Aβs are generated through sequential proteolysis of the amyloid precursor protein by the γ-secretase complexes (GSECs). Aβ peptide length, modulated by the Presenilin (PSEN) and APH-1 subunits of GSEC, is critical for Alzheimer's pathogenesis. Despite high relevance, mechanistic understanding of the proteolysis of Aβ, and its modulation by APH-1, remain incomplete. Here, we report cryo-EM structures of human GSEC (PSEN1/APH-1B) reconstituted into lipid nanodiscs in apo form and in complex with the intermediate Aβ46 substrate without cross-linking. We find that three non-conserved and structurally divergent APH-1 regions establish contacts with PSEN1, and that substrate-binding induces concerted rearrangements in one of the identified PSEN1/APH-1 interfaces, providing structural basis for APH-1 allosteric-like effects. In addition, the GSEC-Aβ46 structure reveals an interaction between Aβ46 and loop 1PSEN1, and identifies three other H-bonding interactions that, according to functional validation, are required for substrate recognition and efficient sequential catalysis.
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Affiliation(s)
- Ivica Odorčić
- Center for Structural Biology, VIB, Brussels, Belgium
- Structural Biology Brussels, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- VIB-KU Leuven Center for Brain & Disease Research, Herestraat 49 box 602, 3000, Leuven, Belgium
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Herestraat 49 box 602, 3000, Leuven, Belgium
| | - Mohamed Belal Hamed
- VIB-KU Leuven Center for Brain & Disease Research, Herestraat 49 box 602, 3000, Leuven, Belgium
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Herestraat 49 box 602, 3000, Leuven, Belgium
| | - Sam Lismont
- VIB-KU Leuven Center for Brain & Disease Research, Herestraat 49 box 602, 3000, Leuven, Belgium
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Herestraat 49 box 602, 3000, Leuven, Belgium
| | - Lucía Chávez-Gutiérrez
- VIB-KU Leuven Center for Brain & Disease Research, Herestraat 49 box 602, 3000, Leuven, Belgium.
- Department of Neurosciences, Leuven Brain Institute, KU Leuven, Herestraat 49 box 602, 3000, Leuven, Belgium.
| | - Rouslan G Efremov
- Center for Structural Biology, VIB, Brussels, Belgium.
- Structural Biology Brussels, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
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3
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Titball RW. The Molecular Architecture and Mode of Action of Clostridium perfringens ε-Toxin. Toxins (Basel) 2024; 16:180. [PMID: 38668605 PMCID: PMC11053738 DOI: 10.3390/toxins16040180] [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: 03/02/2024] [Revised: 03/31/2024] [Accepted: 04/02/2024] [Indexed: 04/29/2024] Open
Abstract
Clostridium perfringens ε-toxin has long been associated with a severe enterotoxaemia of livestock animals, and more recently, was proposed to play a role in the etiology of multiple sclerosis in humans. The remarkable potency of the toxin has intrigued researchers for many decades, who suggested that this indicated an enzymatic mode of action. Recently, there have been major breakthroughs by finding that it is a pore-forming toxin which shows exquisite specificity for cells bearing the myelin and lymphocyte protein (MAL) receptor. This review details the molecular structures of the toxin, the evidence which identifies MAL as the receptor and the possible roles of other cell membrane components in toxin binding. The information on structure and mode of action has allowed the functions of individual amino acids to be investigated and has led to the creation of mutants with reduced toxicity that could serve as vaccines. In spite of this progress, there are still a number of key questions around the mode of action of the toxin which need to be further investigated.
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4
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Shin YC, Latorre-Muro P, Djurabekova A, Zdorevskyi O, Bennett CF, Burger N, Song K, Xu C, Sharma V, Liao M, Puigserver P. Structural basis of respiratory complexes adaptation to cold temperatures. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.16.575914. [PMID: 38293190 PMCID: PMC10827213 DOI: 10.1101/2024.01.16.575914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
In response to cold, mammals activate brown fat for respiratory-dependent thermogenesis reliant on the electron transport chain (1, 2). Yet, the structural basis of respiratory complex adaptation to cold remains elusive. Herein we combined thermoregulatory physiology and cryo-EM to study endogenous respiratory supercomplexes exposed to different temperatures. A cold-induced conformation of CI:III 2 (termed type 2) was identified with a ∼25° rotation of CIII 2 around its inter-dimer axis, shortening inter-complex Q exchange space, and exhibiting different catalytic states which favor electron transfer. Large-scale supercomplex simulations in lipid membrane reveal how unique lipid-protein arrangements stabilize type 2 complexes to enhance catalytic activity. Together, our cryo-EM studies, multiscale simulations and biochemical analyses unveil the mechanisms and dynamics of respiratory adaptation at the structural and energetic level.
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5
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McMullan G, Naydenova K, Mihaylov D, Yamashita K, Peet MJ, Wilson H, Dickerson JL, Chen S, Cannone G, Lee Y, Hutchings KA, Gittins O, Sobhy MA, Wells T, El-Gomati MM, Dalby J, Meffert M, Schulze-Briese C, Henderson R, Russo CJ. Structure determination by cryoEM at 100 keV. Proc Natl Acad Sci U S A 2023; 120:e2312905120. [PMID: 38011573 PMCID: PMC10710074 DOI: 10.1073/pnas.2312905120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/02/2023] [Indexed: 11/29/2023] Open
Abstract
Electron cryomicroscopy can, in principle, determine the structures of most biological molecules but is currently limited by access, specimen preparation difficulties, and cost. We describe a purpose-built instrument operating at 100 keV-including advances in electron optics, detection, and processing-that makes structure determination fast and simple at a fraction of current costs. The instrument attains its theoretical performance limits, allowing atomic resolution imaging of gold test specimens and biological molecular structure determination in hours. We demonstrate its capabilities by determining the structures of eleven different specimens, ranging in size from 140 kDa to 2 MDa, using a fraction of the data normally required. CryoEM with a microscope designed specifically for high-efficiency, on-the-spot imaging of biological molecules will expand structural biology to a wide range of previously intractable problems.
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Affiliation(s)
- Greg McMullan
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Katerina Naydenova
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Daniel Mihaylov
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Keitaro Yamashita
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Mathew J. Peet
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Hugh Wilson
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Joshua L. Dickerson
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Shaoxia Chen
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Giuseppe Cannone
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Yang Lee
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Katherine A. Hutchings
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Olivia Gittins
- Newcastle University, Newcastle upon TyneNE2 4HH, United Kingdom
| | - Mohamed A. Sobhy
- King Abdullah University of Science and Technology, Thuwal23955, Saudi Arabia
| | - Torquil Wells
- York Probe Sources Ltd., YorkYO26 6QU, United Kingdom
| | | | - Jason Dalby
- JEOL U.K. Ltd., Welwyn Garden CityAL7 1LT, United Kingdom
| | | | | | - Richard Henderson
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Christopher J. Russo
- Medical Research Council (MRC) Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
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6
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Tomishige N, Bin Nasim M, Murate M, Pollet B, Didier P, Godet J, Richert L, Sako Y, Mély Y, Kobayashi T. HIV-1 Gag targeting to the plasma membrane reorganizes sphingomyelin-rich and cholesterol-rich lipid domains. Nat Commun 2023; 14:7353. [PMID: 37990014 PMCID: PMC10663554 DOI: 10.1038/s41467-023-42994-w] [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: 08/30/2021] [Accepted: 10/26/2023] [Indexed: 11/23/2023] Open
Abstract
Although the human immunodeficiency virus type 1 lipid envelope has been reported to be enriched with host cell sphingomyelin and cholesterol, the molecular mechanism of the enrichment is not well understood. Viral Gag protein plays a central role in virus budding. Here, we report the interaction between Gag and host cell lipids using different quantitative and super-resolution microscopy techniques in combination with specific probes that bind endogenous sphingomyelin and cholesterol. Our results indicate that Gag in the inner leaflet of the plasma membrane colocalizes with the outer leaflet sphingomyelin-rich domains and cholesterol-rich domains, enlarges sphingomyelin-rich domains, and strongly restricts the mobility of sphingomyelin-rich domains. Moreover, Gag multimerization induces sphingomyelin-rich and cholesterol-rich lipid domains to be in close proximity in a curvature-dependent manner. Our study suggests that Gag binds, coalesces, and reorganizes pre-existing lipid domains during assembly.
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Affiliation(s)
- Nario Tomishige
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
| | - Maaz Bin Nasim
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Faculty of Pharmacy, The University of Lahore, Lahore, Pakistan
| | - Motohide Murate
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Brigitte Pollet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Pascal Didier
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Julien Godet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
| | - Toshihide Kobayashi
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
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7
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Bogard A, Finn PW, Smith AR, Flacau IM, Whiting R, Fologea D. Modulation of Voltage-Gating and Hysteresis of Lysenin Channels by Cu 2+ Ions. Int J Mol Sci 2023; 24:12996. [PMID: 37629177 PMCID: PMC10455686 DOI: 10.3390/ijms241612996] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 08/12/2023] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
The intricate voltage regulation presented by lysenin channels reconstituted in artificial lipid membranes leads to a strong hysteresis in conductance, bistability, and memory. Prior investigations on lysenin channels indicate that the hysteresis is modulated by multivalent cations which are also capable of eliciting single-step conformational changes and transitions to stable closed or sub-conducting states. However, the influence on voltage regulation of Cu2+ ions, capable of completely closing the lysenin channels in a two-step process, was not sufficiently addressed. In this respect, we employed electrophysiology approaches to investigate the response of lysenin channels to variable voltage stimuli in the presence of small concentrations of Cu2+ ions. Our experimental results showed that the hysteretic behavior, recorded in response to variable voltage ramps, is accentuated in the presence of Cu2+ ions. Using simultaneous AC/DC stimulation, we were able to determine that Cu2+ prevents the reopening of channels previously closed by depolarizing potentials and the channels remain in the closed state even in the absence of a transmembrane voltage. In addition, we showed that Cu2+ addition reinstates the voltage gating and hysteretic behavior of lysenin channels reconstituted in neutral lipid membranes in which lysenin channels lose their voltage-regulating properties. In the presence of Cu2+ ions, lysenin not only regained the voltage gating but also behaved like a long-term molecular memory controlled by electrical potentials.
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Affiliation(s)
- Andrew Bogard
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, State University, Boise, ID 83725, USA
| | - Pangaea W. Finn
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Aviana R. Smith
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Ilinca M. Flacau
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Rose Whiting
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, State University, Boise, ID 83725, USA
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, State University, Boise, ID 83725, USA
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8
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Mayse LA, Movileanu L. Gating of β-Barrel Protein Pores, Porins, and Channels: An Old Problem with New Facets. Int J Mol Sci 2023; 24:12095. [PMID: 37569469 PMCID: PMC10418385 DOI: 10.3390/ijms241512095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
β barrels are ubiquitous proteins in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. These transmembrane proteins (TMPs) execute a wide variety of tasks. For example, they can serve as transporters, receptors, membrane-bound enzymes, as well as adhesion, structural, and signaling elements. In addition, multimeric β barrels are common structural scaffolds among many pore-forming toxins. Significant progress has been made in understanding the functional, structural, biochemical, and biophysical features of these robust and versatile proteins. One frequently encountered fundamental trait of all β barrels is their voltage-dependent gating. This process consists of reversible or permanent conformational transitions between a large-conductance, highly permeable open state and a low-conductance, solute-restrictive closed state. Several intrinsic molecular mechanisms and environmental factors modulate this universal property of β barrels. This review article outlines the typical signatures of voltage-dependent gating. Moreover, we discuss recent developments leading to a better qualitative understanding of the closure dynamics of these TMPs.
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Affiliation(s)
- Lauren A. Mayse
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, NY 13244, USA;
- Department of Biomedical and Chemical Engineering, Syracuse University, 223 Link Hall, Syracuse, NY 13244, USA
- The BioInspired Institute, Syracuse University, Syracuse, NY 13244, USA
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9
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Marini G, Poland B, Leininger C, Lukoyanova N, Spielbauer D, Barry JK, Altier D, Lum A, Scolaro E, Ortega CP, Yalpani N, Sandahl G, Mabry T, Klever J, Nowatzki T, Zhao JZ, Sethi A, Kassa A, Crane V, Lu AL, Nelson ME, Eswar N, Topf M, Saibil HR. Structural journey of an insecticidal protein against western corn rootworm. Nat Commun 2023; 14:4171. [PMID: 37443175 PMCID: PMC10344926 DOI: 10.1038/s41467-023-39891-7] [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: 01/12/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
The broad adoption of transgenic crops has revolutionized agriculture. However, resistance to insecticidal proteins by agricultural pests poses a continuous challenge to maintaining crop productivity and new proteins are urgently needed to replace those utilized for existing transgenic traits. We identified an insecticidal membrane attack complex/perforin (MACPF) protein, Mpf2Ba1, with strong activity against the devastating coleopteran pest western corn rootworm (WCR) and a novel site of action. Using an integrative structural biology approach, we determined monomeric, pre-pore and pore structures, revealing changes between structural states at high resolution. We discovered an assembly inhibition mechanism, a molecular switch that activates pre-pore oligomerization upon gut fluid incubation and solved the highest resolution MACPF pore structure to-date. Our findings demonstrate not only the utility of Mpf2Ba1 in the development of biotechnology solutions for protecting maize from WCR to promote food security, but also uncover previously unknown mechanistic principles of bacterial MACPF assembly.
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Affiliation(s)
- Guendalina Marini
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Brad Poland
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Chris Leininger
- Corteva Agriscience, Johnston, IA, 50131, USA
- Syngenta, Research Triangle Park, NC, 27709, USA
| | - Natalya Lukoyanova
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
| | | | | | - Dan Altier
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Amy Lum
- Corteva Agriscience, Johnston, IA, 50131, USA
- Willow Biosciences, 319 N Bernardo Ave #4, Mountain View, CA, 94043, USA
| | | | - Claudia Pérez Ortega
- Corteva Agriscience, Johnston, IA, 50131, USA
- Hologic, Inc., 250 Campus Drive, Marlborough, MA, 01752, USA
| | - Nasser Yalpani
- Corteva Agriscience, Johnston, IA, 50131, USA
- Dept. of Biology, University of British Columbia Okanagan, 3187 University Way, Kelowna, BC, V1V 1V7, Canada
| | | | - Tim Mabry
- Corteva Agriscience, Ivesdale, IL, 61851, USA
| | | | | | | | - Amit Sethi
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Adane Kassa
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | - Albert L Lu
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | | | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany.
| | - Helen R Saibil
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
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10
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Whiting R, Stanton S, Kucheriava M, Smith AR, Pitts M, Robertson D, Kammer J, Li Z, Fologea D. Hypo-Osmotic Stress and Pore-Forming Toxins Adjust the Lipid Order in Sheep Red Blood Cell Membranes. MEMBRANES 2023; 13:620. [PMID: 37504986 PMCID: PMC10385129 DOI: 10.3390/membranes13070620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/07/2023] [Accepted: 06/22/2023] [Indexed: 07/29/2023]
Abstract
Lipid ordering in cell membranes has been increasingly recognized as an important factor in establishing and regulating a large variety of biological functions. Multiple investigations into lipid organization focused on assessing ordering from temperature-induced phase transitions, which are often well outside the physiological range. However, particular stresses elicited by environmental factors, such as hypo-osmotic stress or protein insertion into membranes, with respect to changes in lipid status and ordering at constant temperature are insufficiently described. To fill these gaps in our knowledge, we exploited the well-established ability of environmentally sensitive membrane probes to detect intramembrane changes at the molecular level. Our steady state fluorescence spectroscopy experiments focused on assessing changes in optical responses of Laurdan and diphenylhexatriene upon exposure of red blood cells to hypo-osmotic stress and pore-forming toxins at room temperature. We verified our utilized experimental systems by a direct comparison of the results with prior reports on artificial membranes and cholesterol-depleted membranes undergoing temperature changes. The significant changes observed in the lipid order after exposure to hypo-osmotic stress or pore-forming toxins resembled phase transitions of lipids in membranes, which we explained by considering the short-range interactions between membrane components and the hydrophobic mismatch between membrane thickness and inserted proteins. Our results suggest that measurements of optical responses from the membrane probes constitute an appropriate method for assessing the status of lipids and phase transitions in target membranes exposed to mechanical stresses or upon the insertion of transmembrane proteins.
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Affiliation(s)
- Rose Whiting
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Sevio Stanton
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Aviana R Smith
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Matt Pitts
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Daniel Robertson
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Jacob Kammer
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Department of Family Medicine, Idaho College of Osteopathic Medicine, Meridian, ID 83642, USA
| | - Zhiyu Li
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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11
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Mishra S, Roy A, Dutta S. Cryo-EM-based structural insights into supramolecular assemblies of γ-hemolysin from S. aureus reveal the pore formation mechanism. Structure 2023:S0969-2126(23)00085-0. [PMID: 37019111 DOI: 10.1016/j.str.2023.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 01/31/2023] [Accepted: 03/10/2023] [Indexed: 04/07/2023]
Abstract
γ-Hemolysin (γ-HL) is a hemolytic and leukotoxic bicomponent β-pore-forming toxin (β-PFT), a potent virulence factor from the Staphylococcus aureus Newman strain. In this study, we performed single-particle cryoelectron microscopy (cryo-EM) of γ-HL in a lipid environment. We observed clustering and square lattice packing of octameric HlgAB pores on the membrane bilayer and an octahedral superassembly of octameric pore complexes that we resolved at resolution of 3.5 Å. Our atomic model further demonstrated the key residues involved in hydrophobic zipping between the rim domains of adjacent octameric complexes, providing additional structural stability in PFTs post oligomerization. We also observed extra densities at the octahedral and octameric interfaces, providing insights into the plausible lipid-binding residues involved for HlgA and HlgB components. Furthermore, the hitherto elusive N-terminal region of HlgA was also resolved in our cryo-EM map, and an overall mechanism of pore formation for bicomponent β-PFTs is proposed.
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Affiliation(s)
- Suman Mishra
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Anupam Roy
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Somnath Dutta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
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12
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Margheritis E, Kappelhoff S, Cosentino K. Pore-Forming Proteins: From Pore Assembly to Structure by Quantitative Single-Molecule Imaging. Int J Mol Sci 2023; 24:ijms24054528. [PMID: 36901959 PMCID: PMC10003378 DOI: 10.3390/ijms24054528] [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: 01/05/2023] [Revised: 02/11/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023] Open
Abstract
Pore-forming proteins (PFPs) play a central role in many biological processes related to infection, immunity, cancer, and neurodegeneration. A common feature of PFPs is their ability to form pores that disrupt the membrane permeability barrier and ion homeostasis and generally induce cell death. Some PFPs are part of the genetically encoded machinery of eukaryotic cells that are activated against infection by pathogens or in physiological programs to carry out regulated cell death. PFPs organize into supramolecular transmembrane complexes that perforate membranes through a multistep process involving membrane insertion, protein oligomerization, and finally pore formation. However, the exact mechanism of pore formation varies from PFP to PFP, resulting in different pore structures with different functionalities. Here, we review recent insights into the molecular mechanisms by which PFPs permeabilize membranes and recent methodological advances in their characterization in artificial and cellular membranes. In particular, we focus on single-molecule imaging techniques as powerful tools to unravel the molecular mechanistic details of pore assembly that are often obscured by ensemble measurements, and to determine pore structure and functionality. Uncovering the mechanistic elements of pore formation is critical for understanding the physiological role of PFPs and developing therapeutic approaches.
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13
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Cannone G, Kompaniiets D, Graham S, White MF, Spagnolo L. Structure of the Saccharolobus solfataricus type III-D CRISPR effector. Curr Res Struct Biol 2023; 5:100098. [PMID: 36843655 PMCID: PMC9945777 DOI: 10.1016/j.crstbi.2023.100098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/26/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023] Open
Abstract
CRISPR-Cas is a prokaryotic adaptive immune system, classified into six different types, each characterised by a signature protein. Type III systems, classified based on the presence of a Cas10 subunit, are rather diverse multi-subunit assemblies with a range of enzymatic activities and downstream ancillary effectors. The broad array of current biotechnological CRISPR applications is mainly based on proteins classified as Type II, however recent developments established the feasibility and efficacy of multi-protein Type III CRISPR-Cas effector complexes as RNA-targeting tools in eukaryotes. The crenarchaeon Saccharolobus solfataricus has two type III system subtypes (III-B and III-D). Here, we report the cryo-EM structure of the Csm Type III-D complex from S. solfataricus (SsoCsm), which uses CRISPR RNA to bind target RNA molecules, activating the Cas10 subunit for antiviral defence. The structure reveals the complex organisation, subunit/subunit connectivity and protein/guide RNA interactions of the SsoCsm complex, one of the largest CRISPR effectors known.
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Affiliation(s)
- Giuseppe Cannone
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, United Kingdom
| | - Dmytro Kompaniiets
- School of Molecular Biosciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Shirley Graham
- School of Biology, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Malcolm F. White
- School of Biology, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
| | - Laura Spagnolo
- School of Molecular Biosciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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14
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Marshall S, McGill B, Morcrette H, Winlove CP, Chimerel C, Petrov PG, Bokori-Brown M. Interaction of Clostridium perfringens Epsilon Toxin with the Plasma Membrane: The Role of Amino Acids Y42, Y43 and H162. Toxins (Basel) 2022; 14:toxins14110757. [PMID: 36356007 PMCID: PMC9694948 DOI: 10.3390/toxins14110757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/17/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
Clostridium perfringens epsilon toxin (Etx) is a pore forming toxin that causes enterotoxaemia in ruminants and may be a cause of multiple sclerosis in humans. To date, most in vitro studies of Etx have used the Madin-Darby canine kidney (MDCK) cell line. However, studies using Chinese hamster ovary (CHO) cells engineered to express the putative Etx receptor, myelin and lymphocyte protein (MAL), suggest that amino acids important for Etx activity differ between species. In this study, we investigated the role of amino acids Y42, Y43 and H162, previously identified as important in Etx activity towards MDCK cells, in Etx activity towards CHO-human MAL (CHO-hMAL) cells, human red blood cells (hRBCs) and synthetic bilayers using site-directed mutants of Etx. We show that in CHO-hMAL cells Y42 is critical for Etx binding and not Y43 as in MDCK cells, indicating that surface exposed tyrosine residues in the receptor binding domain of Etx impact efficiency of cell binding to MAL-expressing cells in a species-specific manner. We also show that Etx mutant H162A was unable to lyse CHO-hMAL cells, lysed hRBCs, whilst it was able to form pores in synthetic bilayers, providing evidence of the complexity of Etx pore formation in different lipid environments.
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Affiliation(s)
- Skye Marshall
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Beth McGill
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Helen Morcrette
- College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - C. Peter Winlove
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Catalin Chimerel
- Automation Department, Faculty of Electrical Engineering and Computer Science, Transilvania University of Brasov, 500036 Brasov, Romania
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Peter G. Petrov
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
- Correspondence: (P.G.P.); (M.B.-B.); Tel.: +44-1392-724139 (P.G.P.)
| | - Monika Bokori-Brown
- College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
- Correspondence: (P.G.P.); (M.B.-B.); Tel.: +44-1392-724139 (P.G.P.)
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15
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Mondal AK, Lata K, Singh M, Chatterjee S, Chauhan A, Puravankara S, Chattopadhyay K. Cryo-EM elucidates mechanism of action of bacterial pore-forming toxins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184013. [PMID: 35908609 DOI: 10.1016/j.bbamem.2022.184013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/05/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Pore-forming toxins (PFTs) rupture plasma membranes and kill target cells. PFTs are secreted as soluble monomers that undergo drastic structural rearrangements upon interacting with the target membrane and generate transmembrane oligomeric pores. A detailed understanding of the molecular mechanisms of the pore-formation process remains unclear due to limited structural insights regarding the transmembrane oligomeric pore states of the PFTs. However, recent advances in the field of cryo-electron microscopy (cryo-EM) have led to the high-resolution structure determination of the oligomeric pore forms of diverse PFTs. Here, we discuss the pore-forming mechanisms of various PFTs, specifically the mechanistic details contributed by the cryo-EM-based structural studies.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kusum Lata
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Mahendra Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Shamaita Chatterjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Aakanksha Chauhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Sindhoora Puravankara
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, SAS Nagar, Manauli, Mohali 140306, Punjab, India.
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16
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Cryo-EM structure of disease-related prion fibrils provides insights into seeding barriers. Nat Struct Mol Biol 2022; 29:962-965. [PMID: 36097290 PMCID: PMC9639217 DOI: 10.1038/s41594-022-00833-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/03/2022] [Indexed: 11/08/2022]
Abstract
One of the least understood aspects of prion diseases is the structure of infectious prion protein aggregates. Here we report a high-resolution cryo-EM structure of amyloid fibrils formed by human prion protein with the Y145Stop mutation that is associated with a familial prion disease. This structural insight allows us not only to explain previous biochemical findings, but also provides direct support for the conformational adaptability model of prion transmissibility barriers.
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17
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Structural and mechanistic basis for recognition of alternative tRNA precursor substrates by bacterial ribonuclease P. Nat Commun 2022; 13:5120. [PMID: 36045135 PMCID: PMC9433436 DOI: 10.1038/s41467-022-32843-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 08/19/2022] [Indexed: 11/25/2022] Open
Abstract
Binding of precursor tRNAs (ptRNAs) by bacterial ribonuclease P (RNase P) involves an encounter complex (ES) that isomerizes to a catalytic conformation (ES*). However, the structures of intermediates and the conformational changes that occur during binding are poorly understood. Here, we show that pairing between the 5′ leader and 3′RCCA extending the acceptor stem of ptRNA inhibits ES* formation. Cryo-electron microscopy single particle analysis reveals a dynamic enzyme that becomes ordered upon formation of ES* in which extended acceptor stem pairing is unwound. Comparisons of structures with alternative ptRNAs reveals that once unwinding is completed RNase P primarily uses stacking interactions and shape complementarity to accommodate alternative sequences at its cleavage site. Our study reveals active site interactions and conformational changes that drive molecular recognition by RNase P and lays the foundation for understanding how binding interactions are linked to helix unwinding and catalysis. Ribonuclease P efficiently processes all tRNA precursors despite sequence variation at the site of cleavage. Here, authors use high-throughput enzymology and cryoEM to reveal conformational changes that drive recognition by bacterial RNase P.
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18
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Cao B, Nie Y, Guan Z, Chen C, Wang N, Wang Z, Shu C, Zhang J, Zhang D. The crystal structure of Cry78Aa from Bacillus thuringiensis provides insights into its insecticidal activity. Commun Biol 2022; 5:801. [PMID: 35945427 PMCID: PMC9363482 DOI: 10.1038/s42003-022-03754-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 07/22/2022] [Indexed: 11/09/2022] Open
Abstract
Genetically modified plants with insecticidal proteins from Bacillus thuringiensis (Bt) have been successfully utilized to control various kinds of pests in crop production and reduce the abuse of pesticides. However, a limited number of genes are available for the protection of crops from rice planthopper. Recently, Cry78Aa protein from Bt strain C9F1 has been found to have high insecticidal activity against Laodelphax striatellus and Nilaparvata lugens. It is the first reported single-component protein in the world to combat rice planthoppers, making it very promising for use in transgenic crops. The ambiguous mechanism of Cry78Aa functions prevented further engineering or application. Here, we report the crystal structure of Cry78Aa, which consists of two domains: a C-terminal β-pore forming domain belonging to the aerolysin family and an N-terminal trefoil domain resembling the S-type ricin B lectin. Thus, Cry78Aa could represent a distinctive type of β-pore forming toxin. We also found that Cry78Aa binds carbohydrates such as galactose derivatives and is essential for insecticidal activity against Laodelphax striatellus. Our results suggest a mechanism underlying the function of Cry78Aa against rice planthoppers and pave the way to maximizing the usage of the toxin. The crystal structure of the Bacillus thuringiensis protein Cry78Aa shows it consists of a C-terminal β-pore forming domain and an N-terminal trefoil domain and suggests a mechanism underlying the function of Cry78Aa against rice planthoppers.
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Affiliation(s)
- Beibei Cao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yangfan Nie
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zeyuan Guan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chuanyu Chen
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Nancong Wang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zeyu Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Changlong Shu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Jie Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
| | - Delin Zhang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
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19
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Orlando BJ, Dominik PK, Roy S, Ogbu CP, Erramilli SK, Kossiakoff AA, Vecchio AJ. Development, structure, and mechanism of synthetic antibodies that target claudin and Clostridium perfringens enterotoxin complexes. J Biol Chem 2022; 298:102357. [PMID: 35952760 PMCID: PMC9463536 DOI: 10.1016/j.jbc.2022.102357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/15/2022] Open
Abstract
Strains of Clostridium perfringens produce a two-domain enterotoxin (CpE) that afflicts humans and domesticated animals, causing prevalent gastrointestinal illnesses. CpE’s C-terminal domain (cCpE) binds cell surface receptors, followed by a restructuring of its N-terminal domain to form a membrane-penetrating β-barrel pore, which is toxic to epithelial cells of the gut. The claudin family of membrane proteins are known receptors for CpE and also control the architecture and function of cell-cell contacts (tight junctions) that create barriers to intercellular molecular transport. CpE binding and assembly disables claudin barrier function and induces cytotoxicity via β-pore formation, disrupting gut homeostasis; however, a structural basis of this process and strategies to inhibit the claudin–CpE interactions that trigger it are both lacking. Here, we used a synthetic antigen-binding fragment (sFab) library to discover two sFabs that bind claudin-4 and cCpE complexes. We established these sFabs’ mode of molecular recognition and binding properties and determined structures of each sFab bound to claudin-4–cCpE complexes using cryo-EM. The structures reveal that the sFabs bind a shared epitope, but conform distinctly, which explains their unique binding equilibria. Mutagenesis of antigen/sFab interfaces observed therein result in binding changes, validating the structures, and uncovering the sFab’s targeting mechanism. From these insights, we generated a model for CpE’s claudin-bound β-pore that predicted sFabs would not prevent cytotoxicity, which we then verified in vivo. Taken together, this work demonstrates the development and mechanism of claudin/cCpE-binding sFabs that provide a framework and strategy for obstructing claudin/CpE assembly to treat CpE-linked gastrointestinal diseases.
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Affiliation(s)
- Benjamin J Orlando
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824 USA
| | - Pawel K Dominik
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Sourav Roy
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA
| | - Chinemerem P Ogbu
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA.
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20
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Piper SJ, Johnson RM, Wootten D, Sexton PM. Membranes under the Magnetic Lens: A Dive into the Diverse World of Membrane Protein Structures Using Cryo-EM. Chem Rev 2022; 122:13989-14017. [PMID: 35849490 DOI: 10.1021/acs.chemrev.1c00837] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane proteins are highly diverse in both structure and function and can, therefore, present different challenges for structure determination. They are biologically important for cells and organisms as gatekeepers for information and molecule transfer across membranes, but each class of membrane proteins can present unique obstacles to structure determination. Historically, many membrane protein structures have been investigated using highly engineered constructs or using larger fusion proteins to improve solubility and/or increase particle size. Other strategies included the deconstruction of the full-length protein to target smaller soluble domains. These manipulations were often required for crystal formation to support X-ray crystallography or to circumvent lower resolution due to high noise and dynamic motions of protein subdomains. However, recent revolutions in membrane protein biochemistry and cryo-electron microscopy now provide an opportunity to solve high resolution structures of both large, >1 megadalton (MDa), and small, <100 kDa (kDa), drug targets in near-native conditions, routinely reaching resolutions around or below 3 Å. This review provides insights into how the recent advances in membrane biology and biochemistry, as well as technical advances in cryo-electron microscopy, help us to solve structures of a large variety of membrane protein groups, from small receptors to large transporters and more complex machineries.
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Affiliation(s)
- Sarah J Piper
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Rachel M Johnson
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Denise Wootten
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia.,ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
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21
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Goto A, Sakai S, Mizuike A, Yamaji T, Hanada K. Compartmentalization of casein kinase 1 γ CSNK1G controls the intracellular trafficking of ceramide. iScience 2022; 25:104624. [PMID: 35800758 PMCID: PMC9254030 DOI: 10.1016/j.isci.2022.104624] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 03/20/2022] [Accepted: 06/13/2022] [Indexed: 11/28/2022] Open
Abstract
Casein kinase 1 γ (CK1G) is involved in the regulation of various cellular functions. For instance, the ceramide transport protein (CERT), which delivers ceramide to the Golgi apparatus for the synthesis of sphingomyelin (SM), is inactivated when it receives multiple phosphorylation by CK1G. Using human genome-wide gene disruption screening with an SM-binding cytolysin, we found that loss of the C-terminal region of CK1G3 rendered the kinase hyperactive in cells. Deletion of the C-terminal 20 amino acids or mutation of cysteine residues expected to be palmitoylated sites redistributed CK1G3 from cytoplasmic punctate compartments to the nucleocytoplasm. Wild-type CK1G3 exhibited a similar redistribution in the presence of 2-bromopalmitate, a protein palmitoylation inhibitor. Expression of C-terminal mutated CK1G1/2/3 similarly induced the multiple phosphorylation of the CERT SRM, thereby down-regulating de novo SM synthesis. These findings revealed that CK1Gs are regulated by a compartmentalization-based mechanism to access substrates present in specific intracellular organelles. C-terminal region of CSNK1Gs restricts their localization to punctate compartments Loss of the kinase compartmentalization causes hyperphosphorylation of CERT Compartmentalization of CSNK1G controls ceramide transport and de novo SM synthesis
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Affiliation(s)
- Asako Goto
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Shota Sakai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Aya Mizuike
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Toshiyuki Yamaji
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Kentaro Hanada
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan
- Corresponding author
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22
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Hammond K, Moffat J, Mulcahy C, Hoogenboom BW, Ryadnov MG. In situ nanoscale imaging reveals self-concentrating nanomolar antimicrobial pores. NANOSCALE 2022; 14:8586-8593. [PMID: 35574721 DOI: 10.1039/d2nr00434h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Host defence peptides are critical factors of immune systems in all life forms. Considered for therapeutic development in the post-antibiotic era, these molecules rupture microbial membranes at micromolar concentrations. Here we report a self-concentrating mechanism of membrane disruption, which occurs at therapeutically more relevant nanomolar concentrations. Induced by a four-helix bacteriocin the mechanism manifests in a multi-modal disruption pattern. Using in situ atomic force microscopy we show that the pattern and its kinetic profiles remain the same in a range of nano-to-micromolar concentrations. We reveal that the bacteriocin creates its own boundaries in phospholipid bilayers in which it self-concentrates to promote transmembrane poration. The findings offer an exploitable insight into nanomolar antimicrobial mechanisms.
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Affiliation(s)
- Katharine Hammond
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Physics & Astronomy, University College London, London WC1E 6BT, UK
| | - Jonathan Moffat
- Oxford Instruments Asylum Research, Halifax Road, High Wycombe, HP12 3SE, UK
| | - Chris Mulcahy
- Oxford Instruments Asylum Research, Halifax Road, High Wycombe, HP12 3SE, UK
| | - Bart W Hoogenboom
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Physics & Astronomy, University College London, London WC1E 6BT, UK
| | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.
- Department of Physics, King's College London, London, WC2R 2LS, UK
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23
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Structural Basis of the Immunity Mechanisms of Pediocin-like Bacteriocins. Appl Environ Microbiol 2022; 88:e0048122. [PMID: 35703550 DOI: 10.1128/aem.00481-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pediocin-like bacteriocins, also designated class IIa bacteriocins, are ribosomally synthesized antimicrobial peptides targeting species closely related to the producers. They act on the cytoplasmic membrane of Gram-positive cells by dissipating the transmembrane electrical potential through pore formation with the mannose phosphotransferase system (man-PTS) as the target/receptor. Bacteriocin-producing strains also synthesize a cognate immunity protein that protects them against their own bacteriocins. Herein, we report the cryo-electron microscopy structure of the bacteriocin-receptor-immunity ternary complex from Lactobacillus sakei. The complex structure reveals that pediocin-like bacteriocins bind to the same position on the Core domain of man-PTS, while the C-terminal helical tails of bacteriocins delimit the opening range of the Core domain away from the Vmotif domain to facilitate transmembrane pore formation. Upon attack of bacteriocins from the extracellular side, man-PTS exposes its cytosolic side for recognition of the N-terminal four-helix bundle of the immunity protein. The C-terminal loop of the immunity protein then inserts into the pore and blocks leakage induced by bacteriocins. Elucidation of the toxicity and immunity mechanisms of pediocin-like bacteriocins could support the design of novel bacteriocins against antibiotic-resistant pathogenic bacteria. IMPORTANCE Pediocin-like bacteriocins, ribosomally synthesized antimicrobial peptides, are generally co-expressed with cognate immunity proteins to protect the bacteriocin-producing strain from its own bacteriocin. Bacteriocins are considered potential alternatives to conventional antibiotics in the context of the bacterial resistance crisis, but the immunity mechanism is unclear. This study uncovered the mechanisms of action and immunity of class IIa bacteriocins.
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Cordelier S, Crouzet J, Gilliard G, Dorey S, Deleu M, Dhondt-Cordelier S. Deciphering the role of plant plasma membrane lipids in response to invasion patterns: how could biology and biophysics help? JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2765-2784. [PMID: 35560208 DOI: 10.1093/jxb/erab517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 11/25/2021] [Indexed: 06/15/2023]
Abstract
Plants have to constantly face pathogen attacks. To cope with diseases, they have to detect the invading pathogen as early as possible via the sensing of conserved motifs called invasion patterns. The first step of perception occurs at the plasma membrane. While many invasion patterns are perceived by specific proteinaceous immune receptors, several studies have highlighted the influence of the lipid composition and dynamics of the plasma membrane in the sensing of invasion patterns. In this review, we summarize current knowledge on how some microbial invasion patterns could interact with the lipids of the plasma membrane, leading to a plant immune response. Depending on the invasion pattern, different mechanisms are involved. This review outlines the potential of combining biological with biophysical approaches to decipher how plasma membrane lipids are involved in the perception of microbial invasion patterns.
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Affiliation(s)
- Sylvain Cordelier
- Université de Reims Champagne Ardenne, RIBP EA 4707, USC INRAE 1488, SFR Condorcet FR CNRS 3417, 51100 Reims, France
| | - Jérôme Crouzet
- Université de Reims Champagne Ardenne, RIBP EA 4707, USC INRAE 1488, SFR Condorcet FR CNRS 3417, 51100 Reims, France
| | - Guillaume Gilliard
- Laboratoire de Biophysique Moléculaire aux Interfaces, SFR Condorcet FR CNRS 3417, TERRA Research Center, Gembloux Agro-Bio Tech, Université de Liège, 2 Passage des Déportés, B-5030 Gembloux, Belgium
| | - Stéphan Dorey
- Université de Reims Champagne Ardenne, RIBP EA 4707, USC INRAE 1488, SFR Condorcet FR CNRS 3417, 51100 Reims, France
| | - Magali Deleu
- Laboratoire de Biophysique Moléculaire aux Interfaces, SFR Condorcet FR CNRS 3417, TERRA Research Center, Gembloux Agro-Bio Tech, Université de Liège, 2 Passage des Déportés, B-5030 Gembloux, Belgium
| | - Sandrine Dhondt-Cordelier
- Université de Reims Champagne Ardenne, RIBP EA 4707, USC INRAE 1488, SFR Condorcet FR CNRS 3417, 51100 Reims, France
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Durell SR, Kayed R, Guy HR. The amyloid concentric β‐barrel hypothesis: Models of amyloid beta 42 oligomers and annular protofibrils. Proteins 2022; 90:1190-1209. [DOI: 10.1002/prot.26301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 12/31/2021] [Accepted: 01/11/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Stewart R. Durell
- Laboratory of Cell Biology, National Cancer Institute National Institutes of Health Bethesda Maryland USA
| | - Rakez Kayed
- UTMB Mitchell Center for Neurodegenerative Diseases, Department of Neurology University of Texas Medical Branch Galveston Texas USA
| | - H. Robert Guy
- Amyloid Research Consultants (ARC) Cochiti Lake New Mexico USA
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Lee S, Kim Y. Ribosome preparation from turquoise killifish skeletal muscle for cryo-EM. STAR Protoc 2022; 3:101087. [PMID: 35072116 PMCID: PMC8761774 DOI: 10.1016/j.xpro.2021.101087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Ribosomes are composed of a mix of ribosomal RNAs and proteins; this composition varies depending on time, condition, and organism. Here, we present an optimized protocol for preparation of intact ribosomes from the skeletal muscle of the turquoise killifish. We also detail the steps for ribosome quantification and cryo-EM grid preparation. This protocol can enable the identification of heterogeneous ribosome structures that vary by fish age or in response to specific conditions. Ribosome enrichment from turquoise killifish skeletal muscle for cryo-EM Steps to check quality and quantity of enriched ribosomes Preparation of cryo-EM grid with enriched ribosome Enables comparison of ribosome structures in varying conditions
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Structural and mechanistic basis of reiterative transcription initiation. Proc Natl Acad Sci U S A 2022; 119:2115746119. [PMID: 35082149 PMCID: PMC8812562 DOI: 10.1073/pnas.2115746119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2021] [Indexed: 02/02/2023] Open
Abstract
Reiterative transcription initiation, observed at promoters that contain homopolymeric sequences at the transcription start site, generates RNA products having 5' sequences noncomplementary to the DNA template. Here, using crystallography and cryoelectron microscopy to define structures, protein-DNA photocrosslinking to map positions of RNAP leading and trailing edges relative to DNA, and single-molecule DNA nanomanipulation to assess RNA polymerase (RNAP)-dependent DNA unwinding, we show that RNA extension in reiterative transcription initiation 1) occurs without DNA scrunching; 2) involves a short, 2- to 3-bp, RNA-DNA hybrid; and 3) generates RNA that exits RNAP through the portal by which scrunched nontemplate-strand DNA exits RNAP in standard transcription initiation. The results establish that, whereas RNA extension in standard transcription initiation proceeds through a scrunching mechanism, RNA extension in reiterative transcription initiation proceeds through a slippage mechanism, with slipping of RNA relative to DNA within a short RNA-DNA hybrid, and with extrusion of RNA from RNAP through an alternative RNA exit.
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Durell SR, Guy HR. The amyloid concentric β-barrel hypothesis: Models of synuclein oligomers, annular protofibrils, lipoproteins, and transmembrane channels. Proteins 2022; 90:512-542. [PMID: 34570382 PMCID: PMC8988847 DOI: 10.1002/prot.26249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/13/2021] [Indexed: 02/03/2023]
Abstract
Amyloid beta (Aβ of Alzheimer's disease) and α-synuclein (α-Syn of Parkinson's disease) form large fibrils. Evidence is increasing however that much smaller oligomers are more toxic and that these oligomers can form transmembrane ion channels. We have proposed previously that Aβ42 oligomers, annular protofibrils, and ion channels adopt concentric β-barrel molecular structures. Here we extend that hypothesis to the superfamily of α, β, and γ-synucleins. Our models of numerous synuclein oligomers, annular protofibrils, tubular protofibrils, lipoproteins, and ion channels were developed to be consistent with sizes, shapes, molecular weights, and secondary structures of assemblies as determined by electron microscopy and other studies. The models have the following features: (1) all subunits have identical structures and interactions; (2) they are consistent with conventional β-barrel theory; (3) the distance between walls of adjacent β-barrels is between 0.6 and 1.2 nm; (4) hydrogen bonds, salt bridges, interactions among aromatic side-chains, burial and tight packing of hydrophobic side-chains, and aqueous solvent exposure of hydrophilic side-chains are relatively optimal; and (5) residues that are identical among distantly related homologous proteins cluster in the interior of most oligomers whereas residues that are hypervariable are exposed on protein surfaces. Atomic scale models of some assemblies were developed.
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Affiliation(s)
- Stewart R Durell
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - H Robert Guy
- Amyloid Research Consultants (ARC), Cochiti Lake, New Mexico, USA
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Structural insights into inhibitor regulation of the DNA repair protein DNA-PKcs. Nature 2022; 601:643-648. [PMID: 34987222 PMCID: PMC8791830 DOI: 10.1038/s41586-021-04274-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/19/2021] [Indexed: 01/29/2023]
Abstract
The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) has a central role in non-homologous end joining, one of the two main pathways that detect and repair DNA double-strand breaks (DSBs) in humans1,2. DNA-PKcs is of great importance in repairing pathological DSBs, making DNA-PKcs inhibitors attractive therapeutic agents for cancer in combination with DSB-inducing radiotherapy and chemotherapy3. Many of the selective inhibitors of DNA-PKcs that have been developed exhibit potential as treatment for various cancers4. Here we report cryo-electron microscopy (cryo-EM) structures of human DNA-PKcs natively purified from HeLa cell nuclear extracts, in complex with adenosine-5′-(γ-thio)-triphosphate (ATPγS) and four inhibitors (wortmannin, NU7441, AZD7648 and M3814), including drug candidates undergoing clinical trials. The structures reveal molecular details of ATP binding at the active site before catalysis and provide insights into the modes of action and specificities of the competitive inhibitors. Of note, binding of the ligands causes movement of the PIKK regulatory domain (PRD), revealing a connection between the p-loop and PRD conformations. Electrophoretic mobility shift assay and cryo-EM studies on the DNA-dependent protein kinase holoenzyme further show that ligand binding does not have a negative allosteric or inhibitory effect on assembly of the holoenzyme complex and that inhibitors function through direct competition with ATP. Overall, the structures described in this study should greatly assist future efforts in rational drug design targeting DNA-PKcs, demonstrating the potential of cryo-EM in structure-guided drug development for large and challenging targets. Cryo-electron microscopy structures of DNA-dependent protein kinase catalytic subunit bound to ATPγS and four inhibitors (wortmannin, NU7441, AZD7648 and M3814) provide molecular details and insights useful for drug design.
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Sych T, Levental KR, Sezgin E. Lipid–Protein Interactions in Plasma Membrane Organization and Function. Annu Rev Biophys 2022; 51:135-156. [DOI: 10.1146/annurev-biophys-090721-072718] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Lipid–protein interactions in cells are involved in various biological processes, including metabolism, trafficking, signaling, host–pathogen interactions, and transmembrane transport. At the plasma membrane, lipid–protein interactions play major roles in membrane organization and function. Several membrane proteins have motifs for specific lipid binding, which modulate protein conformation and consequent function. In addition to such specific lipid–protein interactions, protein function can be regulated by the dynamic, collective behavior of lipids in membranes. Emerging analytical, biochemical, and computational technologies allow us to study the influence of specific lipid–protein interactions, as well as the collective behavior of membranes on protein function. In this article, we review the recent literature on lipid–protein interactions with a specific focus on the current state-of-the-art technologies that enable novel insights into these interactions. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Taras Sych
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
| | - Kandice R. Levental
- Department of Molecular Physiology and Biological Physics, Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA
| | - Erdinc Sezgin
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden;,
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
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Sengupta N, Mondal AK, Mishra S, Chattopadhyay K, Dutta S. Single-particle cryo-EM reveals conformational variability of the oligomeric VCC β-barrel pore in a lipid bilayer. J Cell Biol 2021; 220:212683. [PMID: 34617964 PMCID: PMC8504180 DOI: 10.1083/jcb.202102035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/25/2021] [Accepted: 09/19/2021] [Indexed: 11/22/2022] Open
Abstract
Vibrio cholerae cytolysin (VCC) is a water-soluble, membrane-damaging, pore-forming toxin (PFT) secreted by pathogenic V. cholerae, which causes eukaryotic cell death by altering the plasma membrane permeability. VCC self-assembles on the cell surface and undergoes a dramatic conformational change from prepore to heptameric pore structure. Over the past few years, several high-resolution structures of detergent-solubilized PFTs have been characterized. However, high-resolution structural characterization of small β-PFTs in a lipid environment is still rare. Therefore, we used single-particle cryo-EM to characterize the structure of the VCC oligomer in large unilamellar vesicles, which is the first atomic-resolution cryo-EM structure of VCC. From our study, we were able to provide the first documented visualization of the rim domain amino acid residues of VCC interacting with lipid membrane. Furthermore, cryo-EM characterization of lipid bilayer–embedded VCC suggests interesting conformational variabilities, especially in the transmembrane channel, which could have a potential impact on the pore architecture and assist us in understanding the pore formation mechanism.
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Affiliation(s)
- Nayanika Sengupta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Anish Kumar Mondal
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Suman Mishra
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Kausik Chattopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Somnath Dutta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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Structural basis of pore formation in the mannose phosphotransferase system (man-PTS) by pediocin PA-1. Appl Environ Microbiol 2021; 88:e0199221. [PMID: 34851716 DOI: 10.1128/aem.01992-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriocins are ribosomally synthesized bacterial antimicrobial peptides that have a narrow spectrum of antibacterial activity against species closely related to the producers. Pediocin-like (or class IIa) bacteriocins (PLBs) exhibit antibacterial activity against several Gram-positive bacterial strains by forming pores in the cytoplasmic membrane of target cells with the specific receptor, the mannose phosphotransferase system (man-PTS). In this study, we report the cryo-electron microscopy structures of man-PTS from Listeria monocytogenes alone and its complex with pediocin PA-1, the first and most extensively studied representative PLB at a resolution of 3.12 Å and 2.45 Å, respectively. The structures revealed that the binding of pediocin PA-1 opens the Core domain of man-PTS away from its Vmotif domain, creating a pore through the cytoplasmic membranes of target cells. During this process, the N-terminal β-sheet region of pediocin PA-1 can specifically attach to the extracellular surface of the man-PTS Core domain, whereas the C-terminal half penetrates the membrane and cracks the man-PTS like a wedge. Thus, our findings shed light on a design of novel PLBs that can kill target pathogenic bacteria. Importance Listeria monocytogenes is a ubiquitous microorganism responsible for listeriosis, a rare but severe disease in humans who become infected by ingesting contaminated food products (i.e., dairy, meat, fish, and vegetables), which have a fatality rate of 33%. Pediocin PA-1 is an important commercial additive used in food production to inhibit Listeria species. The mannose phosphotransferase system (man-PTS) is responsible for the sensitivity of Listeria monocytogenes to pediocin PA-1. In this study, we report the cryo-EM structures of man-PTS from Listeria monocytogenes alone and its complex with pediocin PA-1 at a resolution of 3.12 Å and 2.45 Å, respectively. Our results facilitate the understanding of the mode of action of class IIa bacteriocins as an alternative to antibiotics.
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Challenges and approaches to studying pore-forming proteins. Biochem Soc Trans 2021; 49:2749-2765. [PMID: 34747994 PMCID: PMC8892993 DOI: 10.1042/bst20210706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/19/2021] [Accepted: 10/06/2021] [Indexed: 02/07/2023]
Abstract
Pore-forming proteins (PFPs) are a broad class of molecules that comprise various families, structural folds, and assembly pathways. In nature, PFPs are most often deployed by their host organisms to defend against other organisms. In humans, this is apparent in the immune system, where several immune effectors possess pore-forming activity. Furthermore, applications of PFPs are found in next-generation low-cost DNA sequencing, agricultural crop protection, pest control, and biosensing. The advent of cryoEM has propelled the field forward. Nevertheless, significant challenges and knowledge-gaps remain. Overcoming these challenges is particularly important for the development of custom, purpose-engineered PFPs with novel or desired properties. Emerging single-molecule techniques and methods are helping to address these unanswered questions. Here we review the current challenges, problems, and approaches to studying PFPs.
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Scott-Fordsmand JJ, Amorim MJB. The Curious Case of Earthworms and COVID-19. BIOLOGY 2021; 10:biology10101043. [PMID: 34681142 PMCID: PMC8533077 DOI: 10.3390/biology10101043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022]
Abstract
Simple Summary Earthworms have been used for centuries in traditional medicine, and more than a century ago were praised by Charles Darwin as one of the most important organisms in the history of the world. These worms are well-studied with a wealth of information available, for example on the genome, the gene expression, the immune system, the general biology, and ecology. These worms live in many habitats, and they had to find solutions for severe environmental challenges. The common compost worm, Eisenia fetida, has developed a unique mechanism to deal with intruding (nano)materials, bacteria, and viruses. It deals with the intruders by covering these with a defence toxin (lysenin) targeted to kill the intruder. We outline how this mechanism probably can be used as a therapeutic model for human COVID-19 (Severe Acute Respiratory Syndrome Coronavirus 2, SARS-CoV-2) and other corona viruses. Abstract Earthworms have been used for centuries in traditional medicine and are used globally as an ecotoxicological standard test species. Studies of the earthworm Eisenia fetida have shown that exposure to nanomaterials activates a primary corona-response, which is covering the nanomaterial with native proteins, the same response as to biological invaders such as a virus. We outline that the earthworm Eisenia fetida is possibly immune to COVID-19 (Severe Acute Respiratory Syndrome Coronavirus 2, SARS-CoV-2), and we describe the likely mechanisms of highly receptor-specific pore-forming proteins (PFPs). A non-toxic version of this protein is available, and we hypothesize that it is possible to use the earthworm’s PFPs based anti-viral mechanism as a therapeutic model for human SARS-CoV-2 and other corona viruses. The proteins can be used as a drug, for example, delivered with a nanoparticle in a similar way to the current COVID-19 vaccines. Obviously, careful consideration should be given to the potential risk of toxicity elicited by lysenin for in vivo usage. We aim to share this view to activate its exploration by the wider scientific community while promoting a potential therapeutic development.
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Affiliation(s)
- Janeck J. Scott-Fordsmand
- Department of Biosciences, Aarhus University, 8600 Silkeborg, Denmark
- Correspondence: ; Tel.: +45-4025-6803
| | - Monica J. B. Amorim
- Department of Biology & CESAM, University of Aveiro, 3810-193 Aveiro, Portugal;
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Kouadio JL, Duff S, Aikins M, Zheng M, Rydel T, Chen D, Bretsnyder E, Xia C, Zhang J, Milligan J, Evdokimov A, Nageotte J, Yin Y, Moar W, Giddings K, Park Y, Jerga A, Haas J. Structural and functional characterization of Mpp75Aa1.1, a putative beta-pore forming protein from Brevibacillus laterosporus active against the western corn rootworm. PLoS One 2021; 16:e0258052. [PMID: 34634061 PMCID: PMC8504720 DOI: 10.1371/journal.pone.0258052] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 09/16/2021] [Indexed: 12/16/2022] Open
Abstract
The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a major corn pest of significant economic importance in the United States. The continuous need to control this corn maize pest and the development of field-evolved resistance toward all existing transgenic maize (Zea mays L.) expressing Bacillus thuringiensis (Bt) insecticidal proteins against WCR has prompted the development of new insect-protected crops expressing distinct structural classes of insecticidal proteins. In this current study, we describe the crystal structure and functional characterization of Mpp75Aa1.1, which represents the first corn rootworm (CRW) active insecticidal protein member of the ETX_MTX2 sub-family of beta-pore forming proteins (β-PFPs), and provides new and effective protection against WCR feeding. The Mpp75Aa1.1 crystal structure was solved at 1.94 Å resolution. The Mpp75Aa1.1 is processed at its carboxyl-terminus by WCR midgut proteases, forms an oligomer, and specifically interacts with putative membrane-associated binding partners on the midgut apical microvilli to cause cellular tissue damage resulting in insect death. Alanine substitution of the surface-exposed amino acids W206, Y212, and G217 within the Mpp75Aa1.1 putative receptor binding domain I demonstrates that at least these three amino acids are required for WCR activity. The distinctive spatial arrangement of these amino acids suggests that they are part of a receptor binding epitope, which may be unique to Mpp75Aa1.1 and not present in other ETX_MTX2 proteins that do not have WCR activity. Overall, this work establishes that Mpp75Aa1.1 shares a mode of action consistent with traditional WCR-active Bt proteins despite significant structural differences.
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Affiliation(s)
- Jean-Louis Kouadio
- Bayer Crop Science, Chesterfield, Missouri, United States of America
- * E-mail:
| | - Stephen Duff
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Michael Aikins
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - Meiying Zheng
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Timothy Rydel
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Danqi Chen
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Eric Bretsnyder
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Chunsheng Xia
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jun Zhang
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jason Milligan
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Artem Evdokimov
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey Nageotte
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yong Yin
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - William Moar
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Kara Giddings
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Yoonseong Park
- Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America
| | - Agoston Jerga
- Bayer Crop Science, Chesterfield, Missouri, United States of America
| | - Jeffrey Haas
- Bayer Crop Science, Chesterfield, Missouri, United States of America
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Coscia F, Löwe J. Cryo-EM structure of the full-length Lon protease from Thermus thermophilus. FEBS Lett 2021; 595:2691-2700. [PMID: 34591981 PMCID: PMC8835725 DOI: 10.1002/1873-3468.14199] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 11/30/2022]
Abstract
In bacteria, Lon is a large hexameric ATP‐dependent protease that targets misfolded and also folded substrates, some of which are involved in cell division and survival of cellular stress. The N‐terminal domain of Lon facilitates substrate recognition, but how the domains confer such activity has remained unclear. Here, we report the full‐length structure of Lon protease from Thermus thermophilus at 3.9 Å resolution in a substrate‐engaged state. The six N‐terminal domains are arranged in three pairs, stabilized by coiled‐coil segments and forming an additional channel for substrate sensing and entry into the AAA+ ring. Sequence conservation analysis and proteolysis assays confirm that this architecture is required for the degradation of both folded and unfolded substrates in bacteria.
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Affiliation(s)
- Francesca Coscia
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
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Kulma M, Anderluh G. Beyond pore formation: reorganization of the plasma membrane induced by pore-forming proteins. Cell Mol Life Sci 2021; 78:6229-6249. [PMID: 34387717 PMCID: PMC11073440 DOI: 10.1007/s00018-021-03914-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/09/2021] [Accepted: 08/03/2021] [Indexed: 12/23/2022]
Abstract
Pore-forming proteins (PFPs) are a heterogeneous group of proteins that are expressed and secreted by a wide range of organisms. PFPs are produced as soluble monomers that bind to a receptor molecule in the host cell membrane. They then assemble into oligomers that are incorporated into the lipid membrane to form transmembrane pores. Such pore formation alters the permeability of the plasma membrane and is one of the most common mechanisms used by PFPs to destroy target cells. Interestingly, PFPs can also indirectly manipulate diverse cellular functions. In recent years, increasing evidence indicates that the interaction of PFPs with lipid membranes is not only limited to pore-induced membrane permeabilization but is also strongly associated with extensive plasma membrane reorganization. This includes lateral rearrangement and deformation of the lipid membrane, which can lead to the disruption of target cell function and finally death. Conversely, these modifications also constitute an essential component of the membrane repair system that protects cells from the lethal consequences of pore formation. Here, we provide an overview of the current knowledge on the changes in lipid membrane organization caused by PFPs from different organisms.
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Affiliation(s)
- Magdalena Kulma
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia.
| | - Gregor Anderluh
- Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1001, Ljubljana, Slovenia
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Sun D, Sang Z, Kim YJ, Xiang Y, Cohen T, Belford AK, Huet A, Conway JF, Sun J, Taylor DJ, Schneidman-Duhovny D, Zhang C, Huang W, Shi Y. Potent neutralizing nanobodies resist convergent circulating variants of SARS-CoV-2 by targeting diverse and conserved epitopes. Nat Commun 2021; 12:4676. [PMID: 34344900 PMCID: PMC8333356 DOI: 10.1038/s41467-021-24963-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 07/19/2021] [Indexed: 01/07/2023] Open
Abstract
Interventions against variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are urgently needed. Stable and potent nanobodies (Nbs) that target the receptor binding domain (RBD) of SARS-CoV-2 spike are promising therapeutics. However, it is unknown if Nbs broadly neutralize circulating variants. We found that RBD Nbs are highly resistant to variants of concern (VOCs). High-resolution cryoelectron microscopy determination of eight Nb-bound structures reveals multiple potent neutralizing epitopes clustered into three classes: Class I targets ACE2-binding sites and disrupts host receptor binding. Class II binds highly conserved epitopes and retains activity against VOCs and RBDSARS-CoV. Cass III recognizes unique epitopes that are likely inaccessible to antibodies. Systematic comparisons of neutralizing antibodies and Nbs provided insights into how Nbs target the spike to achieve high-affinity and broadly neutralizing activity. Structure-function analysis of Nbs indicates a variety of antiviral mechanisms. Our study may guide the rational design of pan-coronavirus vaccines and therapeutics.
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Affiliation(s)
- Dapeng Sun
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zhe Sang
- The University of Pittsburgh and Carnegie Mellon University Program for Computational Biology, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yong Joon Kim
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine and Carnegie Mellon University, Pittsburgh, PA, USA
| | - Yufei Xiang
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tomer Cohen
- School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of 6, Jerusalem, Israel
| | - Anna K Belford
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alexis Huet
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - James F Conway
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ji Sun
- Department of Structure Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Dina Schneidman-Duhovny
- School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of 6, Jerusalem, Israel.
| | - Cheng Zhang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA.
| | - Yi Shi
- The University of Pittsburgh and Carnegie Mellon University Program for Computational Biology, Pittsburgh, PA, USA.
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA.
- Medical Scientist Training Program, University of Pittsburgh School of Medicine and Carnegie Mellon University, Pittsburgh, PA, USA.
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Mondal AK, Chattopadhyay K. Structures and functions of the membrane-damaging pore-forming proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:241-288. [PMID: 35034720 DOI: 10.1016/bs.apcsb.2021.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pore-forming proteins (PFPs) of the diverse life forms have emerged as the potent cell-killing entities owing to their specialized membrane-damaging properties. PFPs have the unique ability to perforate the plasma membranes of their target cells, and they exert this functionality by creating oligomeric pores in the membrane lipid bilayer. Pathogenic bacteria employ PFPs as toxins to execute their virulence mechanisms, whereas in the higher vertebrates PFPs are deployed as the part of the immune system and to generate inflammatory responses. PFPs are the unique dimorphic proteins that are generally synthesized as water-soluble molecules, and transform into membrane-inserted oligomeric pore assemblies upon interacting with the target membranes. In spite of sharing very little sequence similarity, PFPs from diverse organisms display incredible structural similarity. Yet, at the same time, structure-function mechanisms of the PFPs document remarkable versatility. Such notions establish PFPs as the fascinating model system to explore variety of unsolved issues pertaining to the structure-function paradigm of the proteins that interact and act in the membrane environment. In this article, we discuss our current understanding regarding the structural basis of the pore-forming functions of the diverse class of PFPs. We attempt to highlight the similarities and differences in their structures, membrane pore-formation mechanisms, and their implications for the various biological processes, ranging from the bacterial virulence mechanisms to the inflammatory immune response generation in the higher animals.
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Affiliation(s)
- Anish Kumar Mondal
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India
| | - Kausik Chattopadhyay
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab, India.
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Weissenberger G, Henderikx RJM, Peters PJ. Understanding the invisible hands of sample preparation for cryo-EM. Nat Methods 2021; 18:463-471. [PMID: 33963356 DOI: 10.1038/s41592-021-01130-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 03/30/2021] [Indexed: 02/03/2023]
Abstract
Cryo-electron microscopy (cryo-EM) is rapidly becoming an attractive method in the field of structural biology. With the exploding popularity of cryo-EM, sample preparation must evolve to prevent congestion in the workflow. The dire need for improved microscopy samples has led to a diversification of methods. This Review aims to categorize and explain the principles behind various techniques in the preparation of vitrified samples for the electron microscope. Various aspects and challenges in the workflow are discussed, from sample optimization and carriers to deposition and vitrification. Reliable and versatile specimen preparation remains a challenge, and we hope to give guidelines and posit future directions for improvement.
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Affiliation(s)
- Giulia Weissenberger
- CryoSol-World, Maastricht, the Netherlands.,Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands
| | - Rene J M Henderikx
- CryoSol-World, Maastricht, the Netherlands.,Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands
| | - Peter J Peters
- Maastricht Multimodal Molecular Imaging Institute (M4i), Division of Nanoscopy, Maastricht University, Maastricht, the Netherlands.
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Branching out the aerolysin, ETX/MTX-2 and Toxin_10 family of pore forming proteins. J Invertebr Pathol 2021; 186:107570. [PMID: 33775676 DOI: 10.1016/j.jip.2021.107570] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/15/2020] [Accepted: 03/09/2021] [Indexed: 01/28/2023]
Abstract
Organisms have evolved mechanisms in which cellular membranes can both be targeted and punctured thereby killing the targeted cell. One such mechanism involves the deployment of pore forming proteins (PFPs) which function by oligomerizing on cell membranes and inserting a physical pore spanning the membrane. This pore can lead to cell death by either causing osmotic flux or allowing the delivery of a secondary toxin. Pore forming proteins can be broadly classified into different families depending on the structure of the final pore; either α-PFPs using channels made from α -helices or β-PFPs using channels made from β-barrels. There are many different β-PFPs and an emerging superfamily is the aerolysin-ETX/MTX-2 superfamily. A comparison between the members of this superfamily reveals the pore forming domain is a common module yet the receptor binding region is highly variable. These structural and architectural variations lead to differences in the target recognition and determine the site of activity. Closer investigation of the topology of the family also suggests that the Toxin_10 family of PFPs could be considered as part of the aerolysin-ETX/MTX-2 superfamily. Comparatively, far less is known about how Toxin_10 proteins assemble into the final pore structure than aerolysin-ETX/MTX-2 proteins. This review aims to collate the pore forming protein members and bridge the structural similarities between the aerolysin-ETX/MTX-2 superfamily and the insecticidal Toxin_10 subfamily.
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Kampjut D, Steiner J, Sazanov LA. Cryo-EM grid optimization for membrane proteins. iScience 2021; 24:102139. [PMID: 33665558 PMCID: PMC7900225 DOI: 10.1016/j.isci.2021.102139] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/11/2021] [Accepted: 01/29/2021] [Indexed: 01/12/2023] Open
Abstract
Cryo-EM grid preparation is an important bottleneck in protein structure determination, especially for membrane proteins, typically requiring screening of a large number of conditions. We systematically investigated the effects of buffer components, blotting conditions and grid types on the outcome of grid preparation of five different membrane protein samples. Aggregation was the most common type of problem which was addressed by changing detergents, salt concentration or reconstitution of proteins into nanodiscs or amphipols. We show that the optimal concentration of detergent is between 0.05 and 0.4% and that the presence of a low concentration of detergent with a high critical micellar concentration protects the proteins from denaturation at the air-water interface. Furthermore, we discuss the strategies for achieving an adequate ice thickness, particle coverage and orientation distribution on free ice and on support films. Our findings provide a clear roadmap for comprehensive screening of conditions for cryo-EM grid preparation of membrane proteins. Cryo-EM grid optimization is a limiting factor in protein structure determination Membrane proteins require additional optimization of parameters such as surfactants Aggregation and intactness of proteins depend on detergent and salt concentrations Support films can help preserve protein intactness and improve particle coverage
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Affiliation(s)
- Domen Kampjut
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Julia Steiner
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Leonid A Sazanov
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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Li Q, Babinchak WM, Surewicz WK. Cryo-EM structure of amyloid fibrils formed by the entire low complexity domain of TDP-43. Nat Commun 2021; 12:1620. [PMID: 33712624 PMCID: PMC7955110 DOI: 10.1038/s41467-021-21912-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/19/2021] [Indexed: 12/21/2022] Open
Abstract
Amyotrophic lateral sclerosis and several other neurodegenerative diseases are associated with brain deposits of amyloid-like aggregates formed by the C-terminal fragments of TDP-43 that contain the low complexity domain of the protein. Here, we report the cryo-EM structure of amyloid formed from the entire TDP-43 low complexity domain in vitro at pH 4. This structure reveals single protofilament fibrils containing a large (139-residue), tightly packed core. While the C-terminal part of this core region is largely planar and characterized by a small proportion of hydrophobic amino acids, the N-terminal region contains numerous hydrophobic residues and has a non-planar backbone conformation, resulting in rugged surfaces of fibril ends. The structural features found in these fibrils differ from those previously found for fibrils generated from short protein fragments. The present atomic model for TDP-43 LCD fibrils provides insight into potential structural perturbations caused by phosphorylation and disease-related mutations.
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Affiliation(s)
- Qiuye Li
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - W Michael Babinchak
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Witold K Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA.
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Abstract
CryoEM has become the method of choice for determining the structure of large macromolecular complexes in multiple conformations, at resolutions where unambiguous atomic models can be built. Two effects that have limited progress in single-particle cryoEM are (i) beam-induced movement during image acquisition and (ii) protein adsorption and denaturation at the air-water interface during specimen preparation. While beam-induced movement now appears to have been resolved by all-gold specimen support grids with very small holes, surface effects at the air-water interface are a persistent problem. Strategies to overcome these effects include the use of alternative support films and new techniques for specimen deposition. We examine the future potential of recording perfect images of biological samples for routine structure determination at atomic resolution.
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Sun D, Sang Z, Kim YJ, Xiang Y, Cohen T, Belford AK, Huet A, Conway JF, Sun J, Taylor DJ, Schneidman-Duhovny D, Zhang C, Huang W, Shi Y. Potent neutralizing nanobodies resist convergent circulating variants of SARS-CoV-2 by targeting novel and conserved epitopes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.03.09.434592. [PMID: 33758850 PMCID: PMC7987009 DOI: 10.1101/2021.03.09.434592] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is an urgent need to develop effective interventions resistant to the evolving variants of SARS-CoV-2. Nanobodies (Nbs) are stable and cost-effective agents that can be delivered by novel aerosolization route to treat SARS-CoV-2 infections efficiently. However, it remains unknown if they possess broadly neutralizing activities against the prevalent circulating strains. We found that potent neutralizing Nbs are highly resistant to the convergent variants of concern that evade a large panel of neutralizing antibodies (Abs) and significantly reduce the activities of convalescent or vaccine-elicited sera. Subsequent determination of 9 high-resolution structures involving 6 potent neutralizing Nbs by cryoelectron microscopy reveals conserved and novel epitopes on virus spike inaccessible to Abs. Systematic structural comparison of neutralizing Abs and Nbs provides critical insights into how Nbs uniquely target the spike to achieve high-affinity and broadly neutralizing activity against the evolving virus. Our study will inform the rational design of novel pan-coronavirus vaccines and therapeutics.
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Affiliation(s)
- Dapeng Sun
- Department of Pharmacology and Chemical Biology, University of Pittsburgh
| | - Zhe Sang
- The University of Pittsburgh and Carnegie Mellon University Program for Computational Biology, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, PA, USA
| | - Yong Joon Kim
- Department of Cell Biology, University of Pittsburgh, PA, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine and Carnegie Mellon University, Pittsburgh, PA, USA
| | - Yufei Xiang
- Department of Cell Biology, University of Pittsburgh, PA, USA
| | - Tomer Cohen
- School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
| | | | - Alexis Huet
- Department of Structural Biology, University of Pittsburgh
| | | | - Ji Sun
- Department of Structure Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Derek J. Taylor
- Department of Pharmacology, Case Western Reserve University, Clevaland, OH, USA
- Department of Biochemistry, Case Western Reserve University, Clevaland, OH, USA
| | - Dina Schneidman-Duhovny
- School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of Jerusalem, Israel
| | - Cheng Zhang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University, Clevaland, OH, USA
| | - Yi Shi
- The University of Pittsburgh and Carnegie Mellon University Program for Computational Biology, Pittsburgh, PA, USA
- Department of Cell Biology, University of Pittsburgh, PA, USA
- Medical Scientist Training Program, University of Pittsburgh School of Medicine and Carnegie Mellon University, Pittsburgh, PA, USA
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Kumar A, Sengupta N, Dutta S. Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules. NANOMATERIALS 2021; 11:nano11030643. [PMID: 33808009 PMCID: PMC7999706 DOI: 10.3390/nano11030643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 11/16/2022]
Abstract
In this manuscript, we report the application of graphene oxide (GO) in the preparation of cryo-electron microscopy (cryo-EM) and transmission electron microscopy (TEM) grids. We treated GO with water and organic solvents, such as, methanol, ethanol and isopropanol separately to isolate significantly large GO monolayer flake to fabricate the grids for cryo-EM and TEM study. We implemented a simplified approach to isolate flakes of GO monolayer for constructing the TEM grids, independent of expensive heavy equipment (Langmuir-Blodgett trough, glow-discharge system, carbon-evaporator or plasma-cleaner or peristaltic pumps). We employed confocal microscopy, SEM and TEM to characterize the flake size, stability and transparency of the GO monolayer and atomic force microscopy (AFM) to probe the depth of GO coated grids. Additionally, GO grids are visualized at cryogenic condition for suitability of GO monolayer for cryo-EM study. In addition, GO-Met-H2O grids reduce the effect of preferred orientation of biological macromolecules within the amorphous ice. The power-spectrum and contrast-transfer-function unequivocally suggest that GO-Met-H2O fabricated holey grids have excellent potential for application in high-resolution structural characterization of biomolecules. Furthermore, only 200 movies and ~8000 70S ribosome particles are selected on GO-coated grids for cryo-EM reconstruction to achieve high-resolution structure.
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Affiliation(s)
| | | | - Somnath Dutta
- Correspondence: ; Tel.: +91-080-2293-3453; Fax: +91-080-2360-0535
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Gilbert RJC. Electron microscopy as a critical tool in the determination of pore forming mechanisms in proteins. Methods Enzymol 2021; 649:71-102. [PMID: 33712203 DOI: 10.1016/bs.mie.2021.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electron microscopy has consistently played an important role in the description of pore-forming protein systems. The discovery of pore-forming proteins has depended on visualization of the structural pores formed by their oligomeric protein complexes, and as electron microscopy has advanced technologically so has the degree of insight it has been able to give. This review considers a large number of published studies of pore-forming complexes in prepore and pore states determined using single-particle cryo-electron microscopy. Sample isolation and preparation, imaging and image analysis, structure determination and optimization of results are all discussed alongside challenges which pore-forming proteins particularly present. The review also considers the use made of cryo-electron tomography to study pores within their membrane environment and which will prove an increasingly important approach for the future.
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Affiliation(s)
- Robert J C Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
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Abstract
Pore-forming proteins (PFPs) include virulence factors that are produced by many pathogenic bacteria. However, PFPs also comprise non-virulence factors, such as apoptotic Bcl2-like proteins, and also occur in non-pathogenic bacteria and indeed in all kingdoms of life. Pore-forming proteins are an ancient class of proteins, which are tremendously powerful in damaging cell membranes. In general, upon binding to lipid membranes, they convert from the soluble monomeric form into an oligomeric state, and then undergo a dramatic conformational change to form transmembrane pores. Thus, PFPs render the plasma membrane of their target cells permeable to solutes, potentially leading to cell death, or to more subtle manipulations of cellular functions. Recent cryo-EM and X-ray crystallography studies revealed high-resolution structures of several PFPs in their pre-pore and pore states, however many aspects regarding the cues that induce pore formation, the pre-pore to pore conformational transition, the mechanism of membrane permeation and associated dynamics are still less well understood, and direct visualization of the dynamics of these transitions are missing. Using high-speed atomic force microscopy (HS-AFM), the kinetics of oligomerization and the pre-pore to pore transition dynamics of various PFPs, such as Listeriolysin O (LLO), lysenin, and Perforin-2 (PFN2), could be studied. These studies revealed that LLO does not form pores of regular shape or size, but rather forms membrane inserted arcs that propagate and damage lipid membranes as lineactants. In contrast, lysenin forms stable pre-pore and pore nonameric rings and HS-AFM allowed to study their diffusion on and the pH-dependent insertion into the membrane. Similarly, PFN2 underwent pre-pore to pore transition upon acidification. The openness of the HS-AFM system allowed the transition to be imaged in real time and revealed that all observed molecules transitioned into the pore state within 3s. In this chapter, we detail protocols to prepare lipids, form supported lipid bilayers, and provide guidelines for real-time, real-space HS-AFM observations of PFPs in action.
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Li Y, Li Y, Mengist HM, Shi C, Zhang C, Wang B, Li T, Huang Y, Xu Y, Jin T. Structural Basis of the Pore-Forming Toxin/Membrane Interaction. Toxins (Basel) 2021; 13:toxins13020128. [PMID: 33572271 PMCID: PMC7914777 DOI: 10.3390/toxins13020128] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/13/2021] [Accepted: 02/02/2021] [Indexed: 12/14/2022] Open
Abstract
With the rapid growth of antibiotic-resistant bacteria, it is urgent to develop alternative therapeutic strategies. Pore-forming toxins (PFTs) belong to the largest family of virulence factors of many pathogenic bacteria and constitute the most characterized classes of pore-forming proteins (PFPs). Recent studies revealed the structural basis of several PFTs, both as soluble monomers, and transmembrane oligomers. Upon interacting with host cells, the soluble monomer of bacterial PFTs assembles into transmembrane oligomeric complexes that insert into membranes and affect target cell-membrane permeability, leading to diverse cellular responses and outcomes. Herein we have reviewed the structural basis of pore formation and interaction of PFTs with the host cell membrane, which could add valuable contributions in comprehensive understanding of PFTs and searching for novel therapeutic strategies targeting PFTs and interaction with host receptors in the fight of bacterial antibiotic-resistance.
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Affiliation(s)
- Yajuan Li
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Yuelong Li
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Hylemariam Mihiretie Mengist
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Cuixiao Shi
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Caiying Zhang
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
| | - Bo Wang
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Tingting Li
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Ying Huang
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
| | - Yuanhong Xu
- Department of Clinical Laboratory, the First Affiliated Hospital of Anhui Medical University, Hefei 230022, China; (Y.L.); (C.S.); (B.W.); (T.L.); (Y.H.)
- Correspondence: (Y.X.); (T.J.); Tel.: +86-13505694447 (Y.X.); +86-17605607323 (T.J.)
| | - Tengchuan Jin
- Hefei National Laboratory for Physical Sciences at Microscale, Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, Division of Life Sciences and Medicine, School of Basic Medical Sciences, University of Science and Technology of China, Hefei 230027, China; (Y.L.); (H.M.M.); (C.Z.)
- Correspondence: (Y.X.); (T.J.); Tel.: +86-13505694447 (Y.X.); +86-17605607323 (T.J.)
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Larpin Y, Besançon H, Babiychuk VS, Babiychuk EB, Köffel R. Small Pore-Forming Toxins Different Membrane Area Binding and Ca 2+ Permeability of Pores Determine Cellular Resistance of Monocytic Cells. Toxins (Basel) 2021; 13:toxins13020126. [PMID: 33572185 PMCID: PMC7914786 DOI: 10.3390/toxins13020126] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/27/2021] [Accepted: 02/04/2021] [Indexed: 01/06/2023] Open
Abstract
Pore-forming toxins (PFTs) form multimeric trans-membrane pores in cell membranes that differ in pore channel diameter (PCD). Cellular resistance to large PFTs (>20 nm PCD) was shown to rely on Ca2+ influx activated membrane repair mechanisms. Small PFTs (<2 nm PCD) were shown to exhibit a high cytotoxic activity, but host cell response and membrane repair mechanisms are less well studied. We used monocytic immune cell lines to investigate the cellular resistance and host membrane repair mechanisms to small PFTs lysenin (Eisenia fetida) and aerolysin (Aeromonas hydrophila). Lysenin, but not aerolysin, is shown to induce Ca2+ influx from the extracellular space and to activate Ca2+ dependent membrane repair mechanisms. Moreover, lysenin binds to U937 cells with higher efficiency as compared to THP-1 cells, which is in line with a high sensitivity of U937 cells to lysenin. In contrast, aerolysin equally binds to U937 or THP-1 cells, but in different plasma membrane areas. Increased aerolysin induced cell death of U937 cells, as compared to THP-1 cells, is suggested to be a consequence of cap-like aerolysin binding. We conclude that host cell resistance to small PFTs attack comprises binding efficiency, pore localization, and capability to induce Ca2+ dependent membrane repair mechanisms.
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