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Szyszka TN, Andreas MP, Lie F, Miller LM, Adamson LSR, Fatehi F, Twarock R, Draper BE, Jarrold MF, Giessen TW, Lau YH. Point mutation in a virus-like capsid drives symmetry reduction to form tetrahedral cages. Proc Natl Acad Sci U S A 2024; 121:e2321260121. [PMID: 38722807 PMCID: PMC11098114 DOI: 10.1073/pnas.2321260121] [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: 12/06/2023] [Accepted: 03/25/2024] [Indexed: 05/18/2024] Open
Abstract
Protein capsids are a widespread form of compartmentalization in nature. Icosahedral symmetry is ubiquitous in capsids derived from spherical viruses, as this geometry maximizes the internal volume that can be enclosed within. Despite the strong preference for icosahedral symmetry, we show that simple point mutations in a virus-like capsid can drive the assembly of unique symmetry-reduced structures. Starting with the encapsulin from Myxococcus xanthus, a 180-mer bacterial capsid that adopts the well-studied viral HK97 fold, we use mass photometry and native charge detection mass spectrometry to identify a triple histidine point mutant that forms smaller dimorphic assemblies. Using cryoelectron microscopy, we determine the structures of a precedented 60-mer icosahedral assembly and an unexpected 36-mer tetrahedron that features significant geometric rearrangements around a new interaction surface between capsid protomers. We subsequently find that the tetrahedral assembly can be generated by triple-point mutation to various amino acids and that even a single histidine point mutation is sufficient to form tetrahedra. These findings represent a unique example of tetrahedral geometry when surveying all characterized encapsulins, HK97-like capsids, or indeed any virus-derived capsids reported in the Protein Data Bank, revealing the surprising plasticity of capsid self-assembly that can be accessed through minimal changes in the protein sequence.
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Affiliation(s)
- Taylor N. Szyszka
- School of Chemistry, The University of Sydney, Camperdown, NSW2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Camperdown, NSW2006, Australia
| | - Michael P. Andreas
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Felicia Lie
- School of Chemistry, The University of Sydney, Camperdown, NSW2006, Australia
| | - Lohra M. Miller
- Chemistry Department, Indiana University, Bloomington, IN47405
| | | | - Farzad Fatehi
- Department of Mathematics, University of York, YorkYO10 5DD, United Kingdom
- York Cross-Disciplinary Centre for Systems Analysis, University of York, YorkYO10 5DD, United Kingdom
| | - Reidun Twarock
- Department of Mathematics, University of York, YorkYO10 5DD, United Kingdom
- York Cross-Disciplinary Centre for Systems Analysis, University of York, YorkYO10 5DD, United Kingdom
- Department of Biology, University of York, YorkYO10 5DD, United Kingdom
| | | | | | - Tobias W. Giessen
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Yu Heng Lau
- School of Chemistry, The University of Sydney, Camperdown, NSW2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Camperdown, NSW2006, Australia
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Szyszka TN, Andreas MP, Lie F, Miller LM, Adamson LSR, Fatehi F, Twarock R, Draper BE, Jarrold MF, Giessen TW, Lau YH. Point mutation in a virus-like capsid drives symmetry reduction to form tetrahedral cages. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.579038. [PMID: 38370832 PMCID: PMC10871247 DOI: 10.1101/2024.02.05.579038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Protein capsids are a widespread form of compartmentalisation in nature. Icosahedral symmetry is ubiquitous in capsids derived from spherical viruses, as this geometry maximises the internal volume that can be enclosed within. Despite the strong preference for icosahedral symmetry, we show that simple point mutations in a virus-like capsid can drive the assembly of novel symmetry-reduced structures. Starting with the encapsulin from Myxococcus xanthus, a 180-mer bacterial capsid that adopts the well-studied viral HK97 fold, we use mass photometry and native charge detection mass spectrometry to identify a triple histidine point mutant that forms smaller dimorphic assemblies. Using cryo-EM, we determine the structures of a precedented 60-mer icosahedral assembly and an unprecedented 36-mer tetrahedron that features significant geometric rearrangements around a novel interaction surface between capsid protomers. We subsequently find that the tetrahedral assembly can be generated by triple point mutation to various amino acids, and that even a single histidine point mutation is sufficient to form tetrahedra. These findings represent the first example of tetrahedral geometry across all characterised encapsulins, HK97-like capsids, or indeed any virus-derived capsids reported in the Protein Data Bank, revealing the surprising plasticity of capsid self-assembly that can be accessed through minimal changes in protein sequence.
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Affiliation(s)
- Taylor N Szyszka
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Michael P Andreas
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Felicia Lie
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Lohra M Miller
- Chemistry Department, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA
| | - Lachlan S R Adamson
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Farzad Fatehi
- Department of Mathematics, University of York, York, UK
- York Cross-Disciplinary Centre for Systems Analysis, University of York, York, UK
| | - Reidun Twarock
- Department of Mathematics, University of York, York, UK
- York Cross-Disciplinary Centre for Systems Analysis, University of York, York, UK
- Department of Biology, University of York, York, UK
| | - Benjamin E Draper
- Megadalton Solutions Inc., 3750 E Bluebird Ln, Bloomington, IN 47401, USA
| | - Martin F Jarrold
- Chemistry Department, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA
| | - Tobias W Giessen
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yu Heng Lau
- School of Chemistry, The University of Sydney, Camperdown, NSW 2006, Australia
- The University of Sydney Nano Institute, The University of Sydney, Camperdown, NSW 2006, Australia
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Khmelinskaia A, Bethel NP, Fatehi F, Antanasijevic A, Borst AJ, Lai SH, Wang JYJ, Mallik BB, Miranda MC, Watkins AM, Ogohara C, Caldwell S, Wu M, Heck AJR, Veesler D, Ward AB, Baker D, Twarock R, King NP. Local structural flexibility drives oligomorphism in computationally designed protein assemblies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.18.562842. [PMID: 37905007 PMCID: PMC10614843 DOI: 10.1101/2023.10.18.562842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Many naturally occurring protein assemblies have dynamic structures that allow them to perform specialized functions. For example, clathrin coats adopt a wide variety of architectures to adapt to vesicular cargos of various sizes. Although computational methods for designing novel self-assembling proteins have advanced substantially over the past decade, most existing methods focus on designing static structures with high accuracy. Here we characterize the structures of three distinct computationally designed protein assemblies that each form multiple unanticipated architectures, and identify flexibility in specific regions of the subunits of each assembly as the source of structural diversity. Cryo-EM single-particle reconstructions and native mass spectrometry showed that only two distinct architectures were observed in two of the three cases, while we obtained six cryo-EM reconstructions that likely represent a subset of the architectures present in solution in the third case. Structural modeling and molecular dynamics simulations indicated that the surprising observation of a defined range of architectures, instead of non-specific aggregation, can be explained by constrained flexibility within the building blocks. Our results suggest that deliberate use of structural flexibility as a design principle will allow exploration of previously inaccessible structural and functional space in designed protein assemblies.
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