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Khaykelson D, Asor R, Zhao Z, Schlicksup CJ, Zlotnick A, Raviv U. Guanidine Hydrochloride-Induced Hepatitis B Virus Capsid Disassembly Hysteresis. Biochemistry 2024; 63:1543-1552. [PMID: 38787909 PMCID: PMC11191408 DOI: 10.1021/acs.biochem.4c00077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/20/2024] [Accepted: 04/25/2024] [Indexed: 05/26/2024]
Abstract
Hepatitis B virus (HBV) displays remarkable self-assembly capabilities that interest the scientific community and biotechnological industries as HBV is leading to an annual mortality of up to 1 million people worldwide (especially in Africa and Southeast Asia). When the ionic strength is increased, hepatitis B virus-like particles (VLPs) can assemble from dimers of the first 149 residues of the HBV capsid protein core assembly domain (Cp149). Using solution small-angle X-ray scattering, we investigated the disassembly of the VLPs by titrating guanidine hydrochloride (GuHCl). Measurements were performed with and without 1 M NaCl, added either before or after titrating GuHCl. Fitting the scattering curves to a linear combination of atomic models of Cp149 dimer (the subunit) and T = 3 and T = 4 icosahedral capsids revealed the mass fraction of the dimer in each structure in all the titration points. Based on the mass fractions, the variation in the dimer-dimer association standard free energy was calculated as a function of added GuHCl, showing a linear relation between the interaction strength and GuHCl concentration. Using the data, we estimated the energy barriers for assembly and disassembly and the critical nucleus size for all of the assembly reactions. Extrapolating the standard free energy to [GuHCl] = 0 showed an evident hysteresis in the assembly process, manifested by differences in the dimer-dimer association standard free energy obtained for the disassembly reactions compared with the equivalent assembly reactions. Similar hysteresis was observed in the energy barriers for assembly and disassembly and the critical nucleus size. The results suggest that above 1.5 M, GuHCl disassembled the capsids by attaching to the protein and adding steric repulsion, thereby weakening the hydrophobic attraction.
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Affiliation(s)
- Daniel Khaykelson
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Roi Asor
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Zhongchao Zhao
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Christopher John Schlicksup
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Adam Zlotnick
- Department
of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Uri Raviv
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
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2
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Raviv U, Asor R, Shemesh A, Ginsburg A, Ben-Nun T, Schilt Y, Levartovsky Y, Ringel I. Insight into structural biophysics from solution X-ray scattering. J Struct Biol 2023; 215:108029. [PMID: 37741561 DOI: 10.1016/j.jsb.2023.108029] [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: 04/29/2023] [Revised: 08/09/2023] [Accepted: 09/18/2023] [Indexed: 09/25/2023]
Abstract
The current challenges of structural biophysics include determining the structure of large self-assembled complexes, resolving the structure of ensembles of complex structures and their mass fraction, and unraveling the dynamic pathways and mechanisms leading to the formation of complex structures from their subunits. Modern synchrotron solution X-ray scattering data enable simultaneous high-spatial and high-temporal structural data required to address the current challenges of structural biophysics. These data are complementary to crystallography, NMR, and cryo-TEM data. However, the analysis of solution scattering data is challenging; hence many different analysis tools, listed in the SAS Portal (http://smallangle.org/), were developed. In this review, we start by briefly summarizing classical X-ray scattering analyses providing insight into fundamental structural and interaction parameters. We then describe recent developments, integrating simulations, theory, and advanced X-ray scattering modeling, providing unique insights into the structure, energetics, and dynamics of self-assembled complexes. The structural information is essential for understanding the underlying physical chemistry principles leading to self-assembled supramolecular architectures and computational structural refinement.
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Affiliation(s)
- Uri Raviv
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel; The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel.
| | - Roi Asor
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Asaf Shemesh
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Avi Ginsburg
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Tal Ben-Nun
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Yaelle Schilt
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Yehonatan Levartovsky
- Institute of Chemistry, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Israel Ringel
- Institute for Drug Research, School of Pharmacy, The Hebrew University of Jerusalem, 9112102 Jerusalem, Israel
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3
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Asor R, Singaram SW, Levi-Kalisman Y, Hagan MF, Raviv U. Effect of ionic strength on the assembly of simian vacuolating virus capsid protein around poly(styrene sulfonate). THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:107. [PMID: 37917241 DOI: 10.1140/epje/s10189-023-00363-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 10/09/2023] [Indexed: 11/04/2023]
Abstract
Virus-like particles (VLPs) are noninfectious nanocapsules that can be used for drug delivery or vaccine applications. VLPs can be assembled from virus capsid proteins around a condensing agent, such as RNA, DNA, or a charged polymer. Electrostatic interactions play an important role in the assembly reaction. VLPs assemble from many copies of capsid protein, with a combinatorial number of intermediates. Hence, the mechanism of the reaction is poorly understood. In this paper, we combined solution small-angle X-ray scattering (SAXS), cryo-transmission electron microscopy (TEM), and computational modeling to determine the effect of ionic strength on the assembly of Simian Vacuolating Virus 40 (SV40)-like particles. We mixed poly(styrene sulfonate) with SV40 capsid protein pentamers at different ionic strengths. We then characterized the assembly product by SAXS and cryo-TEM. To analyze the data, we performed Langevin dynamics simulations using a coarse-grained model that revealed incomplete, asymmetric VLP structures consistent with the experimental data. We found that close to physiological ionic strength, [Formula: see text] VLPs coexisted with VP1 pentamers. At lower or higher ionic strengths, incomplete particles coexisted with pentamers and [Formula: see text] particles. Including the simulated structures was essential to explain the SAXS data in a manner that is consistent with the cryo-TEM images.
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Affiliation(s)
- Roi Asor
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel
| | - Surendra W Singaram
- Department of Physics, Brandeis University, 415 South Street, Waltham, 02453, MA, USA
| | - Yael Levi-Kalisman
- Institute of Life Sciences and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel
| | - Michael F Hagan
- Department of Physics, Brandeis University, 415 South Street, Waltham, 02453, MA, USA.
| | - Uri Raviv
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401, Jerusalem, Israel.
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4
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Waltmann C, Kennedy NW, Mills CE, Roth EW, Ikonomova SP, Tullman-Ercek D, Olvera de la Cruz M. Kinetic Growth of Multicomponent Microcompartment Shells. ACS NANO 2023; 17:15751-15762. [PMID: 37552700 DOI: 10.1021/acsnano.3c03353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
An important goal of systems and synthetic biology is to produce high value chemical species in large quantities. Microcompartments, which are protein nanoshells encapsulating catalytic enzyme cargo, could potentially function as tunable nanobioreactors inside and outside cells to generate these high value species. Modifying the morphology of microcompartments through genetic engineering of shell proteins is one viable strategy to tune cofactor and metabolite access to encapsulated enzymes. However, this is a difficult task without understanding how changing interactions between the many different types of shell proteins and enzymes affect microcompartment assembly and shape. Here, we use multiscale molecular dynamics and experimental data to describe assembly pathways available to microcompartments composed of multiple types of shell proteins with varied interactions. As the average interaction between the enzyme cargo and the multiple types of shell proteins is weakened, the shell assembly pathway transitions from (i) nucleating on the enzyme cargo to (ii) nucleating in the bulk and then binding the cargo as it grows to (iii) an empty shell. Atomistic simulations and experiments using the 1,2-propanediol utilization microcompartment system demonstrate that shell protein interactions are highly varied and consistent with our multicomponent, coarse-grained model. Furthermore, our results suggest that intrinsic bending angles control the size of these microcompartments. Overall, our simulations and experiments provide guidance to control microcomparmtent size and assembly by modulating the interactions between shell proteins.
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Affiliation(s)
- Curt Waltmann
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Nolan W Kennedy
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Carolyn E Mills
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Eric W Roth
- Northwestern University Atomic and Nanoscale Characterization Experimentation Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Svetlana P Ikonomova
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Danielle Tullman-Ercek
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Monica Olvera de la Cruz
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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5
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Cardoso-Lima R, Santos-Oliveira R, Souza PFN, Barbosa LRS, Wuite GJL, Alencar LMR. Physical virology: how physics is enabling a better understanding of recent viral invaders. Biophys Rev 2023; 15:611-623. [PMID: 37681101 PMCID: PMC10480132 DOI: 10.1007/s12551-023-01075-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/04/2023] [Indexed: 09/09/2023] Open
Abstract
The world is frequently afflicted by several viral outbreaks that bring diseases and health crises. It is vital to comprehend how viral assemblies' fundamental components work to counteract them. Determining the ultrastructure and nanomechanical characteristics of viruses from a physical standpoint helps categorize their mechanical characteristics, offers insight into new treatment options, and/or shows weak spots that can clarify methods for medication targeting. This study compiles the findings from studies on the ultrastructure and nanomechanical behavior of SARS-CoV-2, ZIKV (Zika virus), and CHIKV (Chikungunya virus) viral particles. With results that uncovered aspects of the organization and the spatial distribution of the proteins on the surface of the viral particle as well as the deformation response of the particles when applied a recurring loading force, this review aims to provide further discussion on the mechanical properties of viral particles at the nanoscale, offering new prospects that could be employed for designing strategies for the prevention and treatment of viral diseases. Supplementary Information The online version contains supplementary material available at 10.1007/s12551-023-01075-4.
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Affiliation(s)
- Ruana Cardoso-Lima
- Physics Department, Laboratory of Biophysics and Nanosystems, Federal University of Maranhão, São Luís, MA Brazil
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Ralph Santos-Oliveira
- Brazilian Nuclear Energy Commission, Nuclear Engineering Institute, Rio de Janeiro, 21941906 Brazil
- Laboratory of Nanoradiopharmacy, Rio de Janeiro State University, Rio de Janeiro, 23070200 Brazil
| | - Pedro Filho Noronha Souza
- Department of Biochemistry, Federal University of Ceará, Fortaleza, CE Brazil
- Drug Research and Development Center, Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, CE Brazil
| | - Leandro R. S. Barbosa
- Department of General Physics, Institute of Physics, University of São Paulo, São Paulo, SP 05508-000 Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-100 Brazil
| | - Gijs J. L. Wuite
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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Abstract
The use of biological enzyme catalysts could have huge ramifications for chemical industries. However, these enzymes are often inactive in nonbiological conditions, such as high temperatures, present in industrial settings. Here, we show that the enzyme PETase (polyethylene terephthalate [PET]), with potential application in plastic recycling, is stabilized at elevated temperature through complexation with random copolymers. We demonstrate this through simulations and experiments on different types of substrates. Our simulations also provide strategies for designing more enzymatically active complexes by altering polymer composition and enzyme charge distribution. Engineered and native enzymes are poised to solve challenges in medicine, bioremediation, and biotechnology. One important goal is the possibility of upcycling polymers using enzymes. However, enzymes are often inactive in industrial, nonbiological conditions. It is particularly difficult to protect water-soluble enzymes at elevated temperatures by methods that preserve their functionality. Through atomistic and coarse-grained molecular dynamics simulations that capture protein conformational change, we show that an enzyme, PETase (polyethylene terephthalate [PET]), can be stabilized at elevated temperatures by complexation with random copolymers into nanoscale aggregates that do not precipitate into macroscopic phases. We demonstrated the efficiency of the method by simulating complexes of random copolymers and the enzyme PETase, which depolymerizes PET, a highly used polymer. These polymers are more industrially viable than peptides and can target specific domains on an enzyme. We design the mean composition of the random copolymers to control the polymer–enzyme surface contacts and the polymer conformation. When positioned on or near the active site, these polymer contacts can further stabilize the conformation of the active site at elevated temperatures. We explore the experimental implications of this active site stabilization method and show that PETase-random copolymer complexes have enhanced activity on both small molecule substrates and solid PET films. These results provide guidelines for engineering enzyme–polymer complexes with enhanced enzyme functionality in nonbiological environments.
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7
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Abstract
We introduce Viral Phrenology, a new scheme for understanding the genomic composition of spherical viruses based on the locations of their structural protrusions. We used icosahedral point arrays to classify 135 distinct viral capsids collected from over 600 capsids available in the VIPERdb. Using gauge points of point arrays, we found 149 unique structural protrusions. We then show how to use the locations of these protrusions to determine the genetic composition of the virus. We then show that ssDNA, dsDNA, dsRNA and ssRNA viruses use different arrangements for distributing their protrusions. We also found that Triangulation number is also partially dependent on the structural protrusions. This analysis begins to tie together Baltimore Classification and Triangulation number using point arrays.
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8
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Zhang W, Jia Q, Teng Y, Yang M, Zhang H, Zhang XE, Wang P, Ge J, Cao S, Li F. An Ultrastable Virus-Like Particle with a Carbon Dot Core and Expanded Sequence Plasticity. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2101717. [PMID: 34302443 DOI: 10.1002/smll.202101717] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/06/2021] [Indexed: 06/13/2023]
Abstract
Ordered bio-inorganic hybridization has evolved for the generation of high-performance materials in living organisms and inspires novel strategies to design artificial hybrid materials. Virus-like particles (VLPs) are attracting extensive interest as self-assembling systems and platforms in the fields of biotechnology and nanotechnology. However, as soft nanomaterials, their structural stability remains a general and fundamental problem in various applications. Here, an ultrastable VLP assembled from the major capsid protein (VP1) of simian virus 40 is reported, which contains a carbon dot (C-dot) core. Co-assembly of VP1 with C-dots led to homogeneous T = 1 VLPs with a fourfold increase in VLP yields. The resultant hybrid VLPs showed markedly enhanced structural stability and sequence plasticity. C-dots and a polyhistidine tag fused to the inner-protruding N-terminus of VP1 contributed synergistically to these enhancements, where extensive and strong noncovalent interactions on the C-dot/VP1 interfaces are responsible according to cryo-EM 3D reconstruction, molecular simulation, and affinity measurements. C-dot-enhanced ultrastable VLPs can serve as a new platform, enabling the fabrication of new architectures for bioimaging, theranostics, nanovaccines, etc. The hybridization strategy is simple and can easily be extended to other VLPs and protein nanoparticle systems.
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Affiliation(s)
- Wenjing Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qingyan Jia
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yibo Teng
- Wuhan Ready science and technology corporation Ltd, Wuhan, 430064, China
| | - Mengsi Yang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xian-En Zhang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing, 100101, China
| | - Pengfei Wang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jiechao Ge
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Sheng Cao
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Feng Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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9
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Li Y, Kennedy NW, Li S, Mills CE, Tullman-Ercek D, Olvera de la Cruz M. Computational and Experimental Approaches to Controlling Bacterial Microcompartment Assembly. ACS CENTRAL SCIENCE 2021; 7:658-670. [PMID: 34056096 PMCID: PMC8155464 DOI: 10.1021/acscentsci.0c01699] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Indexed: 05/13/2023]
Abstract
Bacterial microcompartments compartmentalize the enzymes that aid chemical and energy production in many bacterial species. They are postulated to help bacteria survive in hostile environments. Metabolic engineers are interested in repurposing these organelles for non-native functions. Here, we use computational, theoretical, and experimental approaches to determine mechanisms that effectively control microcompartment self-assembly. We find, via multiscale modeling and mutagenesis studies, the interactions responsible for the binding of hexamer-forming proteins in a model system, the propanediol utilization bacterial microcompartments from Salmonella enterica serovar Typhimurium LT2. We determine how the changes in the microcompartment hexamer protein preferred angles and interaction strengths can modify the assembled morphologies. We demonstrate that such altered strengths and angles are achieved via amino acid mutations. A thermodynamic model provides guidelines to design microcompartments of various morphologies. These findings yield insight in controlled protein assembly and provide principles for assembling microcompartments for biochemical or energy applications as nanoreactors.
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Affiliation(s)
- Yaohua Li
- Department
of Material Science and Engineering, Northwestern
University, Evanston, Illinois 60208, United States
- Applied
Physics Program, Northwestern University, Evanston, Illinois 60208, United States
| | - Nolan W. Kennedy
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Interdisciplinary
Biological Sciences Graduate Program, Northwestern
University, Evanston, Illinois 60208, United States
| | - Siyu Li
- Department
of Material Science and Engineering, Northwestern
University, Evanston, Illinois 60208, United States
| | - Carolyn E. Mills
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Danielle Tullman-Ercek
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- E-mail:
| | - Monica Olvera de la Cruz
- Department
of Material Science and Engineering, Northwestern
University, Evanston, Illinois 60208, United States
- Applied
Physics Program, Northwestern University, Evanston, Illinois 60208, United States
- Department
of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- E-mail:
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10
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Asor R, Schlicksup CJ, Zhao Z, Zlotnick A, Raviv U. Rapidly Forming Early Intermediate Structures Dictate the Pathway of Capsid Assembly. J Am Chem Soc 2020; 142:7868-7882. [PMID: 32233479 PMCID: PMC7242811 DOI: 10.1021/jacs.0c01092] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There are ∼1030 possible intermediates on the assembly path from hepatitis B capsid protein dimers to the 120-dimer capsid. If every intermediate was tested, assembly would often get stuck in an entropic trap and essentially every capsid would follow a unique assembly path. Yet, capsids assemble rapidly with minimal trapped intermediates, a realization of the Levinthal paradox. To understand the fundamental mechanisms of capsid assembly, it is critical to resolve the early stages of the reaction. We have used time-resolved small angle X-ray scattering, which is sensitive to solute size and shape and has millisecond temporal resolution. Scattering curves were fit to a thermodynamically curated library of assembly intermediates, using the principle of maximum entropy. Maximum entropy also provides a physical rationale for the selection of species. We found that the capsid assembly pathway was exquisitely sensitive to initial assembly conditions. With the mildest conditions tested, the reaction appeared to be two-state from dimer to 120-dimer capsid with some dimers-of-dimers and trimers-of-dimers. In slightly more aggressive conditions, we observed transient accumulation of a decamer-of-dimers and the appearance of 90-dimer capsids. In conditions where there is measurable kinetic trapping, we found that highly diverse early intermediates accumulated within a fraction of a second and propagated into long-lived kinetically trapped states (≥90-mer). In all cases, intermediates between 35 and 90 subunits did not accumulate. These results are consistent with the presence of low barrier paths that connect early and late intermediates and direct the ultimate assembly path to late intermediates where assembly can be paused.
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Affiliation(s)
- Roi Asor
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Christopher John Schlicksup
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana 47405, United States
| | - Zhongchao Zhao
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana 47405, United States
| | - Adam Zlotnick
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, Indiana 47405, United States
| | - Uri Raviv
- Institute of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 9190401, Israel
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