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Eren E, Watts NR, Montecinos F, Wingfield PT. Encapsulated Ferritin-like Proteins: A Structural Perspective. Biomolecules 2024; 14:624. [PMID: 38927029 PMCID: PMC11202242 DOI: 10.3390/biom14060624] [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: 04/29/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
Encapsulins are self-assembling nano-compartments that naturally occur in bacteria and archaea. These nano-compartments encapsulate cargo proteins that bind to the shell's interior through specific recognition sequences and perform various metabolic processes. Encapsulation enables organisms to perform chemical reactions without exposing the rest of the cell to potentially harmful substances while shielding cargo molecules from degradation and other adverse effects of the surrounding environment. One particular type of cargo protein, the ferritin-like protein (FLP), is the focus of this review. Encapsulated FLPs are members of the ferritin-like protein superfamily, and they play a crucial role in converting ferrous iron (Fe+2) to ferric iron (Fe+3), which is then stored inside the encapsulin in mineralized form. As such, FLPs regulate iron homeostasis and protect organisms against oxidative stress. Recent studies have demonstrated that FLPs have tremendous potential as biosensors and bioreactors because of their ability to catalyze the oxidation of ferrous iron with high specificity and efficiency. Moreover, they have been investigated as potential targets for therapeutic intervention in cancer drug development and bacterial pathogenesis. Further research will likely lead to new insights and applications for these remarkable proteins in biomedicine and biotechnology.
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Affiliation(s)
| | | | | | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Eren E, Watts NR, Conway JF, Wingfield PT. Myxococcus xanthus encapsulin cargo protein EncD is a flavin-binding protein with ferric reductase activity. Proc Natl Acad Sci U S A 2024; 121:e2400426121. [PMID: 38748579 PMCID: PMC11126975 DOI: 10.1073/pnas.2400426121] [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: 01/08/2024] [Accepted: 04/18/2024] [Indexed: 05/27/2024] Open
Abstract
Encapsulins are protein nanocompartments that regulate cellular metabolism in several bacteria and archaea. Myxococcus xanthus encapsulins protect the bacterial cells against oxidative stress by sequestering cytosolic iron. These encapsulins are formed by the shell protein EncA and three cargo proteins: EncB, EncC, and EncD. EncB and EncC form rotationally symmetric decamers with ferroxidase centers (FOCs) that oxidize Fe+2 to Fe+3 for iron storage in mineral form. However, the structure and function of the third cargo protein, EncD, have yet to be determined. Here, we report the x-ray crystal structure of EncD in complex with flavin mononucleotide. EncD forms an α-helical hairpin arranged as an antiparallel dimer, but unlike other flavin-binding proteins, it has no β-sheet, showing that EncD and its homologs represent a unique class of bacterial flavin-binding proteins. The cryo-EM structure of EncA-EncD encapsulins confirms that EncD binds to the interior of the EncA shell via its C-terminal targeting peptide. With only 100 amino acids, the EncD α-helical dimer forms the smallest flavin-binding domain observed to date. Unlike EncB and EncC, EncD lacks a FOC, and our biochemical results show that EncD instead is a NAD(P)H-dependent ferric reductase, indicating that the M. xanthus encapsulins act as an integrated system for iron homeostasis. Overall, this work contributes to our understanding of bacterial metabolism and could lead to the development of technologies for iron biomineralization and the production of iron-containing materials for the treatment of various diseases associated with oxidative stress.
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Affiliation(s)
- Elif Eren
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
| | - Norman R. Watts
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
| | - James F. Conway
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA15260
| | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, MD20892
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3
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Khaleeq S, Sengupta N, Kumar S, Patel UR, Rajmani RS, Reddy P, Pandey S, Singh R, Dutta S, Ringe RP, Varadarajan R. Neutralizing Efficacy of Encapsulin Nanoparticles against SARS-CoV2 Variants of Concern. Viruses 2023; 15:346. [PMID: 36851560 PMCID: PMC9961482 DOI: 10.3390/v15020346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/22/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023] Open
Abstract
Rapid emergence of the SARS-CoV-2 variants has dampened the protective efficacy of existing authorized vaccines. Nanoparticle platforms offer a means to improve vaccine immunogenicity by presenting multiple copies of desired antigens in a repetitive manner which closely mimics natural infection. We have applied nanoparticle display combined with the SpyTag-SpyCatcher system to design encapsulin-mRBD, a nanoparticle vaccine displaying 180 copies of the monomeric SARS-CoV-2 spike receptor-binding domain (RBD). Here we show that encapsulin-mRBD is strongly antigenic and thermotolerant for long durations. After two immunizations, squalene-in-water emulsion (SWE)-adjuvanted encapsulin-mRBD in mice induces potent and comparable neutralizing antibody titers of 105 against wild-type (B.1), alpha, beta, and delta variants of concern. Sera also neutralizes the recent Omicron with appreciable neutralization titers, and significant neutralization is observed even after a single immunization.
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Affiliation(s)
- Sara Khaleeq
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru 560012, India
| | - Nayanika Sengupta
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru 560012, India
| | - Sahil Kumar
- Virology Unit, Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh 160036, India
| | - Unnatiben Rajeshbhai Patel
- Mynvax Private Limited, 3rd Floor, Brigade MLR Centre, No. 50, Vani Vilas Road, Basavanagudi, Bengaluru 560004, India
| | - Raju S. Rajmani
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru 560012, India
| | - Poorvi Reddy
- Mynvax Private Limited, 3rd Floor, Brigade MLR Centre, No. 50, Vani Vilas Road, Basavanagudi, Bengaluru 560004, India
| | - Suman Pandey
- Mynvax Private Limited, 3rd Floor, Brigade MLR Centre, No. 50, Vani Vilas Road, Basavanagudi, Bengaluru 560004, India
| | - Randhir Singh
- Mynvax Private Limited, 3rd Floor, Brigade MLR Centre, No. 50, Vani Vilas Road, Basavanagudi, Bengaluru 560004, India
| | - Somnath Dutta
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru 560012, India
| | - Rajesh P. Ringe
- Virology Unit, Institute of Microbial Technology, Council of Scientific and Industrial Research (CSIR), Chandigarh 160036, India
| | - Raghavan Varadarajan
- Molecular Biophysics Unit (MBU), Indian Institute of Science, Bengaluru 560012, India
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4
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Chmelyuk NS, Oda VV, Gabashvili AN, Abakumov MA. Encapsulins: Structure, Properties, and Biotechnological Applications. BIOCHEMISTRY (MOSCOW) 2023; 88:35-49. [PMID: 37068871 PMCID: PMC9937530 DOI: 10.1134/s0006297923010042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
In 1994 a new class of prokaryotic compartments was discovered, collectively called "encapsulins" or "nanocompartments". Encapsulin shell protomer proteins self-assemble to form icosahedral structures of various diameters (24-42 nm). Inside of nanocompartments shells, one or several cargo proteins, diverse in their functions, can be encapsulated. In addition, non-native cargo proteins can be loaded into nanocompartments, and shell surfaces can be modified via various compounds, which makes it possible to create targeted drug delivery systems, labels for optical and MRI imaging, and to use encapsulins as bioreactors. This review describes a number of strategies of encapsulins application in various fields of science, including biomedicine and nanobiotechnologies.
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Affiliation(s)
- Nelly S Chmelyuk
- National University of Science and Technology "MISIS", Moscow, 119049, Russia
- Pirogov Russian National Research Medical University, Ministry of Health of the Russian Federation, Moscow, 117977, Russia
| | - Vera V Oda
- National University of Science and Technology "MISIS", Moscow, 119049, Russia
| | - Anna N Gabashvili
- National University of Science and Technology "MISIS", Moscow, 119049, Russia
| | - Maxim A Abakumov
- National University of Science and Technology "MISIS", Moscow, 119049, Russia.
- Pirogov Russian National Research Medical University, Ministry of Health of the Russian Federation, Moscow, 117977, Russia
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5
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Improved interface packing and design opportunities revealed by CryoEM analysis of a designed protein nanocage. Heliyon 2022; 8:e12280. [PMID: 36590526 PMCID: PMC9801105 DOI: 10.1016/j.heliyon.2022.e12280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 11/30/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Symmetric protein assemblies play important roles in nature which makes them an attractive target for engineering. De novo symmetric protein complexes can be created through computational protein design to tailor their properties from first principles, and recently several protein nanocages have been created by bringing together protein components through hydrophobic interactions. Accurate experimental structures of newly-developed proteins are essential to validate their design, improve assembly stability, and tailor downstream applications. We describe the CryoEM structure of the nanocage I3-01, at an overall resolution of 3.5 Å. I3-01, comprising 60 aldolase subunits arranged with icosahedral symmetry, has resisted high-resolution characterization. Some key differences between the refined structure and the original design are identified, such as improved packing of hydrophobic sidechains, providing insight to the resistance of I3-01 to high-resolution averaging. Based on our analysis, we suggest factors important in the design and structural processing of new assemblies.
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6
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Tasneem N, Szyszka TN, Jenner EN, Lau YH. How Pore Architecture Regulates the Function of Nanoscale Protein Compartments. ACS NANO 2022; 16:8540-8556. [PMID: 35583458 DOI: 10.1021/acsnano.2c02178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Self-assembling proteins can form porous compartments that adopt well-defined architectures at the nanoscale. In nature, protein compartments act as semipermeable barriers to enable spatial separation and organization of complex biochemical processes. The compartment pores play a key role in their overall function by selectively controlling the influx and efflux of important biomolecular species. By engineering the pores, the functionality of compartments can be tuned to facilitate non-native applications, such as artificial nanoreactors for catalysis. In this review, we analyze how protein structure determines the porosity and impacts the function of both native and engineered compartments, highlighting the wealth of structural data recently obtained by cryo-EM and X-ray crystallography. Through this analysis, we offer perspectives on how current structural insights can inform future studies into the design of artificial protein compartments as nanoreactors with tunable porosity and function.
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Affiliation(s)
- Nuren Tasneem
- School of Chemistry, The University of Sydney, Eastern Avenue, Camperdown, New South Wales 2006, Australia
| | - Taylor N Szyszka
- School of Chemistry, The University of Sydney, Eastern Avenue, Camperdown, New South Wales 2006, Australia
- University of Sydney Nano Institute, Camperdown, New South Wales 2006, Australia
| | - Eric N Jenner
- School of Chemistry, The University of Sydney, Eastern Avenue, Camperdown, New South Wales 2006, Australia
| | - Yu Heng Lau
- School of Chemistry, The University of Sydney, Eastern Avenue, Camperdown, New South Wales 2006, Australia
- University of Sydney Nano Institute, Camperdown, New South Wales 2006, Australia
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7
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Abstract
Subcellular compartmentalization is a defining feature of all cells. In prokaryotes, compartmentalization is generally achieved via protein-based strategies. The two main classes of microbial protein compartments are bacterial microcompartments and encapsulin nanocompartments. Encapsulins self-assemble into proteinaceous shells with diameters between 24 and 42 nm and are defined by the viral HK97-fold of their shell protein. Encapsulins have the ability to encapsulate dedicated cargo proteins, including ferritin-like proteins, peroxidases, and desulfurases. Encapsulation is mediated by targeting sequences present in all cargo proteins. Encapsulins are found in many bacterial and archaeal phyla and have been suggested to play roles in iron storage, stress resistance, sulfur metabolism, and natural product biosynthesis. Phylogenetic analyses indicate that they share a common ancestor with viral capsid proteins. Many pathogens encode encapsulins, and recent evidence suggests that they may contribute toward pathogenicity. The existing information on encapsulin structure, biochemistry, biological function, and biomedical relevance is reviewed here.
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Affiliation(s)
- Tobias W. Giessen
- Departments of Biomedical Engineering and Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
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8
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Adamson LSR, Tasneem N, Andreas MP, Close W, Jenner EN, Szyszka TN, Young R, Cheah LC, Norman A, MacDermott-Opeskin HI, O'Mara ML, Sainsbury F, Giessen TW, Lau YH. Pore structure controls stability and molecular flux in engineered protein cages. SCIENCE ADVANCES 2022. [PMID: 35119930 DOI: 10.1101/2021.01.27.428512] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Protein cages are a common architectural motif used by living organisms to compartmentalize and control biochemical reactions. While engineered protein cages have featured in the construction of nanoreactors and synthetic organelles, relatively little is known about the underlying molecular parameters that govern stability and flux through their pores. In this work, we systematically designed 24 variants of the Thermotoga maritima encapsulin cage, featuring pores of different sizes and charges. Twelve pore variants were successfully assembled and purified, including eight designs with exceptional thermal stability. While negatively charged mutations were better tolerated, we were able to form stable assemblies covering a full range of pore sizes and charges, as observed in seven new cryo-EM structures at 2.5- to 3.6-Å resolution. Molecular dynamics simulations and stopped-flow experiments revealed the importance of considering both pore size and charge, together with flexibility and rate-determining steps, when designing protein cages for controlling molecular flux.
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Affiliation(s)
- Lachlan S R Adamson
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
| | - Nuren Tasneem
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Michael P Andreas
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - William Close
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Eric N Jenner
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Taylor N Szyszka
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Reginald Young
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Li Chen Cheah
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Alexander Norman
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Camperdown, NSW 2006, Australia
| | | | - Megan L O'Mara
- Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
| | - Frank Sainsbury
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Tobias W Giessen
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Yu Heng Lau
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Camperdown, NSW 2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Campderdown, NSW 2006, Australia
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9
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Adamson LSR, Tasneem N, Andreas MP, Close W, Jenner EN, Szyszka TN, Young R, Cheah LC, Norman A, MacDermott-Opeskin HI, O’Mara ML, Sainsbury F, Giessen TW, Lau YH. Pore structure controls stability and molecular flux in engineered protein cages. SCIENCE ADVANCES 2022; 8:eabl7346. [PMID: 35119930 PMCID: PMC8816334 DOI: 10.1126/sciadv.abl7346] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Protein cages are a common architectural motif used by living organisms to compartmentalize and control biochemical reactions. While engineered protein cages have featured in the construction of nanoreactors and synthetic organelles, relatively little is known about the underlying molecular parameters that govern stability and flux through their pores. In this work, we systematically designed 24 variants of the Thermotoga maritima encapsulin cage, featuring pores of different sizes and charges. Twelve pore variants were successfully assembled and purified, including eight designs with exceptional thermal stability. While negatively charged mutations were better tolerated, we were able to form stable assemblies covering a full range of pore sizes and charges, as observed in seven new cryo-EM structures at 2.5- to 3.6-Å resolution. Molecular dynamics simulations and stopped-flow experiments revealed the importance of considering both pore size and charge, together with flexibility and rate-determining steps, when designing protein cages for controlling molecular flux.
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Affiliation(s)
- Lachlan S. R. Adamson
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
| | - Nuren Tasneem
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Michael P. Andreas
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - William Close
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Eric N. Jenner
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Taylor N. Szyszka
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Reginald Young
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Li Chen Cheah
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Alexander Norman
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Camperdown, NSW 2006, Australia
| | | | - Megan L. O’Mara
- Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
| | - Frank Sainsbury
- CSIRO Future Science Platform in Synthetic Biology, Commonwealth Scientific and Industrial Research Organisation (CSIRO), 41 Boggo Road, Dutton Park, QLD 4102, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia, QLD 4072, Australia
- Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia
| | - Tobias W. Giessen
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
- Corresponding author. (T.W.G.); (Y.H.L.)
| | - Yu Heng Lau
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Camperdown, NSW 2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Campderdown, NSW 2006, Australia
- Corresponding author. (T.W.G.); (Y.H.L.)
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10
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Eren E, Wang B, Winkler DC, Watts NR, Steven AC, Wingfield PT. Structural characterization of the Myxococcus xanthus encapsulin and ferritin-like cargo system gives insight into its iron storage mechanism. Structure 2022; 30:551-563.e4. [PMID: 35150605 PMCID: PMC8995368 DOI: 10.1016/j.str.2022.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/22/2021] [Accepted: 01/18/2022] [Indexed: 10/19/2022]
Abstract
Encapsulins are bacterial organelle-like cages involved in various aspects of metabolism, especially protection from oxidative stress. They can serve as vehicles for a wide range of medical applications. Encapsulin shell proteins are structurally similar to HK97 bacteriophage capsid protein and their function depends on the encapsulated cargos. The Myxococcus xanthus encapsulin system comprises EncA and three cargos: EncB, EncC, and EncD. EncB and EncC are similar to bacterial ferritins that can oxidize Fe+2 to less toxic Fe+3. We analyzed EncA, EncB, and EncC by cryo-EM and X-ray crystallography. Cryo-EM shows that EncA cages can have T = 3 and T = 1 symmetry and that EncA T = 1 has a unique protomer arrangement. Also, we define EncB and EncC binding sites on EncA. X-ray crystallography of EncB and EncC reveals conformational changes at the ferroxidase center and additional metal binding sites, suggesting a mechanism for Fe oxidation and storage within the encapsulin shell.
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11
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Wiryaman T, Toor N. Recent advances in the structural biology of encapsulin bacterial nanocompartments. J Struct Biol X 2022; 6:100062. [PMID: 35146412 PMCID: PMC8802124 DOI: 10.1016/j.yjsbx.2022.100062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/14/2022] [Accepted: 01/20/2022] [Indexed: 02/05/2023] Open
Abstract
Large capsid-like nanocompartments called encapsulins are common in bacteria and archaea and contain cargo proteins with diverse functions. Advances in cryo-electron microscopy have enabled structure determination of many encapsulins in recent years. Here we summarize findings from recent encapsulin structures that have significant implications for their biological roles. We also compare important features such as the E-loop, cargo-peptide binding site, and the fivefold axis channel in different structures. In addition, we describe the discovery of a flavin-binding pocket within the encapsulin shell that may reveal a role for this nanocompartment in iron metabolism.
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Affiliation(s)
| | - Navtej Toor
- University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
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12
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Almeida AV, Carvalho AJ, Pereira AS. Encapsulin nanocages: Protein encapsulation and iron sequestration. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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13
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LaFrance BJ, Cassidy-Amstutz C, Nichols RJ, Oltrogge LM, Nogales E, Savage DF. The encapsulin from Thermotoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein. Sci Rep 2021; 11:22810. [PMID: 34815415 PMCID: PMC8610991 DOI: 10.1038/s41598-021-01932-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/29/2021] [Indexed: 11/09/2022] Open
Abstract
Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based 'organelles' found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~ 25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model Thermotoga maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryo-EM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the Thermotoga maritima encapsulin, the decameric cargo protein with fivefold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.
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Affiliation(s)
- Benjamin J LaFrance
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Caleb Cassidy-Amstutz
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Robert J Nichols
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Luke M Oltrogge
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - David F Savage
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA.
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14
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Rodríguez JM, Allende-Ballestero C, Cornelissen JJLM, Castón JR. Nanotechnological Applications Based on Bacterial Encapsulins. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1467. [PMID: 34206092 PMCID: PMC8229669 DOI: 10.3390/nano11061467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 02/06/2023]
Abstract
Encapsulins are proteinaceous nanocontainers, constructed by a single species of shell protein that self-assemble into 20-40 nm icosahedral particles. Encapsulins are structurally similar to the capsids of viruses of the HK97-like lineage, to which they are evolutionarily related. Nearly all these nanocontainers encase a single oligomeric protein that defines the physiological role of the complex, although a few encapsulate several activities within a single particle. Encapsulins are abundant in bacteria and archaea, in which they participate in regulation of oxidative stress, detoxification, and homeostasis of key chemical elements. These nanocontainers are physically robust, contain numerous pores that permit metabolite flux through the shell, and are very tolerant of genetic manipulation. There are natural mechanisms for efficient functionalization of the outer and inner shell surfaces, and for the in vivo and in vitro internalization of heterologous proteins. These characteristics render encapsulin an excellent platform for the development of biotechnological applications. Here we provide an overview of current knowledge of encapsulin systems, summarize the remarkable toolbox developed by researchers in this field, and discuss recent advances in the biomedical and bioengineering applications of encapsulins.
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Affiliation(s)
- Javier M. Rodríguez
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain; (J.M.R.); (C.A.-B.)
| | - Carolina Allende-Ballestero
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain; (J.M.R.); (C.A.-B.)
| | - Jeroen J. L. M. Cornelissen
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands;
| | - José R. Castón
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, 28049 Madrid, Spain; (J.M.R.); (C.A.-B.)
- Nanobiotechnology Associated Unit CNB-CSIC-IMDEA, Campus Cantoblanco, 28049 Madrid, Spain
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Abstract
Wiryaman & Toor [IUCrJ (2021). 8, 342-350] report the cryo-EM structure of a Thermotoga maritima encapsulin, a nanocompartment that encapsulates a ferritin-like protein cargo. The 2 Å resolution structure offers insights into the active role of this thermostable encapsulin in regulating iron homeostasis to reduce oxidative stress.
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Affiliation(s)
- José R. Castón
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, Spain
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