1
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Peng R, Rochon K, Stagg SM, Mears JA. The Structure of the Drp1 Lattice on Membrane. bioRxiv 2024:2024.04.04.588123. [PMID: 38617273 PMCID: PMC11014616 DOI: 10.1101/2024.04.04.588123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Mitochondrial health relies on the membrane fission mediated by dynamin-related protein 1 (Drp1). Previous structural studies of Drp1 on remodeled membranes were hampered by heterogeneity, leaving a critical gap in the understanding of the mitochondrial fission mechanism. Here we present a cryo-electron microscopy structure of full-length human Drp1 decorated on membrane tubules. Using the reconstruction of average subtracted tubular regions (RASTR) technique, we report that Drp1 forms a locally ordered lattice along the tubule without global helical symmetry. The filaments in the lattice are similar to dynamin rungs with conserved stalk interactions. Adjacent filaments are connected by GTPase domain interactions in a novel stacked conformation. Additionally, we observed contact between Drp1 and membrane that can be assigned to variable domain sequence. We identified two states of the Drp1 lattice representing conformational changes related to membrane curvature differences. Together these structures revealed a putative mechanism by which Drp1 constricts mitochondria membranes in a stepwise, "ratchet" manner.
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Affiliation(s)
- Ruizhi Peng
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, USA
| | - Kristy Rochon
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, USA
- Department of Biological Sciences, Florida State University, Tallahassee, Florida, USA
| | - Jason A Mears
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
- Center for Mitochondrial Diseases, Case Western Reserve University School of Medicine, Cleveland, OH 44106 USA
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2
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Kleywegt GJ, Adams PD, Butcher SJ, Lawson CL, Rohou A, Rosenthal PB, Subramaniam S, Topf M, Abbott S, Baldwin PR, Berrisford JM, Bricogne G, Choudhary P, Croll TI, Danev R, Ganesan SJ, Grant T, Gutmanas A, Henderson R, Heymann JB, Huiskonen JT, Istrate A, Kato T, Lander GC, Lok SM, Ludtke SJ, Murshudov GN, Pye R, Pintilie GD, Richardson JS, Sachse C, Salih O, Scheres SHW, Schroeder GF, Sorzano COS, Stagg SM, Wang Z, Warshamanage R, Westbrook JD, Winn MD, Young JY, Burley SK, Hoch JC, Kurisu G, Morris K, Patwardhan A, Velankar S. Community recommendations on cryoEM data archiving and validation. IUCrJ 2024; 11:140-151. [PMID: 38358351 PMCID: PMC10916293 DOI: 10.1107/s2052252524001246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/06/2024] [Indexed: 02/16/2024]
Abstract
In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for the deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop's motivation and history, the topics discussed, and the resulting consensus recommendations. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations.
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Affiliation(s)
| | - Paul D. Adams
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- University of California, Berkeley, CA, USA
| | | | | | | | | | | | - Maya Topf
- Birkbeck, University of London, London, United Kingdom
| | | | | | | | | | | | | | | | - Sai J. Ganesan
- University of California at San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | | | | | | | - Ryan Pye
- EMBL-EBI, Cambridge, United Kingdom
| | | | | | | | | | | | | | | | | | - Zhe Wang
- EMBL-EBI, Cambridge, United Kingdom
| | | | | | - Martyn D. Winn
- Science and Technology Facilities Council, Research Complex at Harwell, Oxon, United Kingdom
| | - Jasmine Y. Young
- RCSB Protein Data Bank, The State University of New Jersey, NJ, USA
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3
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Kleywegt GJ, Adams PD, Butcher SJ, Lawson CL, Rohou A, Rosenthal PB, Subramaniam S, Topf M, Abbott S, Baldwin PR, Berrisford JM, Bricogne G, Choudhary P, Croll TI, Danev R, Ganesan SJ, Grant T, Gutmanas A, Henderson R, Heymann JB, Huiskonen JT, Istrate A, Kato T, Lander GC, Lok SM, Ludtke SJ, Murshudov GN, Pye R, Pintilie GD, Richardson JS, Sachse C, Salih O, Scheres SHW, Schroeder GF, Sorzano COS, Stagg SM, Wang Z, Warshamanage R, Westbrook JD, Winn MD, Young JY, Burley SK, Hoch JC, Kurisu G, Morris K, Patwardhan A, Velankar S. Community recommendations on cryoEM data archiving and validation: Outcomes of a wwPDB/EMDB workshop on cryoEM data management, deposition and validation. ArXiv 2024:arXiv:2311.17640v3. [PMID: 38076521 PMCID: PMC10705588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop's motivation and history, the topics discussed, and consensus recommendations resulting from the workshop. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations.
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Affiliation(s)
| | - Paul D Adams
- Lawrence Berkeley Laboratory, Berkeley, CA, USA and University of California, Berkeley, CA, USA
| | | | - Catherine L Lawson
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | | | | | | | - Maya Topf
- Birkbeck, University of London, London, UK
| | | | | | | | | | | | | | | | - Sai J Ganesan
- University of California at San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - John D Westbrook
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | - Martyn D Winn
- Science and Technology Facilities Council, Research Complex at Harwell, Oxon, UK
| | - Jasmine Y Young
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | - Stephen K Burley
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
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4
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Esfahani BG, Randolph PS, Peng R, Grant T, Stroupe ME, Stagg SM. SPOT-RASTR - a cryo-EM specimen preparation technique that overcomes problems with preferred orientation and the air/water interface. bioRxiv 2024:2024.01.24.577038. [PMID: 38501120 PMCID: PMC10945588 DOI: 10.1101/2024.01.24.577038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
In cryogenic electron microscopy (cryo-EM), specimen preparation remains a bottleneck despite recent advancements. Classical plunge freezing methods often result in issues like aggregation and preferred orientations at the air/water interface. Many alternative methods have been proposed, but there remains a lack a universal solution, and multiple techniques are often required for challenging samples. Here, we demonstrate the use of lipid nanotubes with nickel NTA headgroups as a platform for cryo-EM sample preparation. His-tagged specimens of interest are added to the tubules, and they can be frozen by conventional plunge freezing. We show that the nanotubes protect samples from the air/water interface and promote a wider range of orientations. The reconstruction of average subtracted tubular regions (RASTR) method allows for the removal of the nanotubule signal from the cryo-EM images resulting in isolated images of specimens of interest. Testing with β-galactosidase validates the method's ability to capture particles at lower concentrations, overcome preferred orientations, and achieve near-atomic resolution reconstructions. Since the nanotubules can be identified and targeted automatically at low magnification, the method enables fully automated data collection. Furthermore, the particles on the tubes can be automatically identified and centered using 2D classification enabling particle picking without requiring prior information. Altogether, our approach that we call specimen preparation on a tube RASTR (SPOT-RASTR) holds promise for overcoming air-water interface and preferred orientation challenges and offers the potential for fully automated cryo-EM data collection and structure determination.
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5
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Paraan M, Nasef M, Chou-Zheng L, Khweis SA, Schoeffler AJ, Hatoum-Aslan A, Stagg SM, Dunkle JA. The structure of a Type III-A CRISPR-Cas effector complex reveals conserved and idiosyncratic contacts to target RNA and crRNA among Type III-A systems. PLoS One 2023; 18:e0287461. [PMID: 37352230 PMCID: PMC10289348 DOI: 10.1371/journal.pone.0287461] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 06/06/2023] [Indexed: 06/25/2023] Open
Abstract
Type III CRISPR-Cas systems employ multiprotein effector complexes bound to small CRISPR RNAs (crRNAs) to detect foreign RNA transcripts and elicit a complex immune response that leads to the destruction of invading RNA and DNA. Type III systems are among the most widespread in nature, and emerging interest in harnessing these systems for biotechnology applications highlights the need for detailed structural analyses of representatives from diverse organisms. We performed cryo-EM reconstructions of the Type III-A Cas10-Csm effector complex from S. epidermidis bound to an intact, cognate target RNA and identified two oligomeric states, a 276 kDa complex and a 318 kDa complex. 3.1 Å density for the well-ordered 276 kDa complex allowed construction of atomic models for the Csm2, Csm3, Csm4 and Csm5 subunits within the complex along with the crRNA and target RNA. We also collected small-angle X-ray scattering data which was consistent with the 276 kDa Cas10-Csm architecture we identified. Detailed comparisons between the S. epidermidis Cas10-Csm structure and the well-resolved bacterial (S. thermophilus) and archaeal (T. onnurineus) Cas10-Csm structures reveal differences in how the complexes interact with target RNA and crRNA which are likely to have functional ramifications. These structural comparisons shed light on the unique features of Type III-A systems from diverse organisms and will assist in improving biotechnologies derived from Type III-A effector complexes.
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Affiliation(s)
- Mohammadreza Paraan
- National Center for In-situ Tomographic Ultramicroscopy, Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States of America
| | - Mohamed Nasef
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL, United States of America
| | - Lucy Chou-Zheng
- Department of Microbiology, University of Illinois, Urbana-Champaign, IL, United States of America
| | - Sarah A. Khweis
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL, United States of America
| | - Allyn J. Schoeffler
- Department of Chemistry and Biochemistry, Loyola University New Orleans, New Orleans, LA, United States of America
| | - Asma Hatoum-Aslan
- Department of Microbiology, University of Illinois, Urbana-Champaign, IL, United States of America
| | - Scott M. Stagg
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, United States of America
| | - Jack A. Dunkle
- Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, AL, United States of America
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6
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Rosenberry TL, Zhou HX, Stagg SM, Paravastu AK. Oligomer Formation by Amyloid-β42 in a Membrane-Mimicking Environment in Alzheimer's Disease. Molecules 2022; 27:8804. [PMID: 36557940 PMCID: PMC9781152 DOI: 10.3390/molecules27248804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/17/2022] [Accepted: 11/23/2022] [Indexed: 12/15/2022] Open
Abstract
The brains of Alzheimer's disease (AD) patients contain numerous amyloid plaques that are diagnostic of the disease. The plaques are primarily composed of the amyloidogenic peptides proteins Aβ40 and Aβ42, which are derived by the processing of the amyloid pre-cursor protein (APP) by two proteases called β-secretase and γ-secretase. Aβ42 differs from Aβ40 in having two additional hydrophobic amino acids, ILE and ALA, at the C-terminus. A small percentage of AD is autosomal dominant (ADAD) and linked either to the genes for the presenilins, which are part of γ-secretase, or APP. Because ADAD shares most pathogenic features with widespread late-onset AD, Aβ peptides have become the focus of AD research. Fibrils formed by the aggregation of these peptides are the major component of plaques and were initially targeted in AD therapy. However, the fact that the abundance of plaques does not correlate well with cognitive decline in AD patients has led investigators to examine smaller Aβ aggregates called oligomers. The low levels and heterogeneity of Aβ oligomers have made the determination of their structures difficult, but recent structure determinations of oligomers either formed or initiated in detergents have been achieved. We report here on the structures of these oligomers and suggest how they may be involved in AD.
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Affiliation(s)
- Terrone L. Rosenberry
- The Departments of Neuroscience and Pharmacology, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Huan-Xiang Zhou
- Departments of Chemistry and Physics, University of Illinois Chicago, Chicago, IL 60608, USA
| | - Scott M. Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- Department of Biological Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Anant K. Paravastu
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
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7
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Peng R, Fu X, Mendez JH, Randolph PS, Bammes BE, Stagg SM. Characterizing the resolution and throughput of the Apollo direct electron detector. J Struct Biol X 2022; 7:100080. [PMID: 36578473 PMCID: PMC9791170 DOI: 10.1016/j.yjsbx.2022.100080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/30/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
Advances in electron detection have been essential to the success of high-resolution cryo-EM structure determination. A new generation of direct electron detector called the Apollo, has been developed by Direct Electron. The Apollo uses a novel event-based MAPS detector custom designed for ultra-fast electron counting. We have evaluated this new camera, finding that it delivers high detective quantum efficiency (DQE) and low coincidence loss, enabling high-quality electron counting data acquisition at up to nearly 80 input electrons per pixel per second. We further characterized the performance of Apollo for single particle cryo-EM on real biological samples. Using mouse apoferritin, Apollo yielded better than 1.9 Å resolution reconstructions at all three tested dose rates from a half-day data collection session each. With longer collection time and improved specimen preparation, mouse apoferritin was reconstructed to 1.66 Å resolution. Applied to a more challenging small protein aldolase, we obtained a 2.24 Å resolution reconstruction. The high quality of the map indicates that the Apollo has sufficiently high DQE to reconstruct smaller proteins and complexes with high-fidelity. Our results demonstrate that the Apollo camera performs well across a broad range of dose rates and is capable of capturing high quality data that produce high-resolution reconstructions for large and small single particle samples.
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Affiliation(s)
- Ruizhi Peng
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
| | - Xiaofeng Fu
- Department of Biological Sciences, 319 Stadium Drive, Tallahassee, FL 32306, United States
| | - Joshua H. Mendez
- Simons Electron Microscopy Center, 89 Convent Avenue, New York, NY 10027, United States
| | - Peter S. Randolph
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
| | - Benjamin E. Bammes
- Direct Electron LP, 13240 Evening Creek Drive South, Suite 311, San Diego, CA 92128, United States
| | - Scott M. Stagg
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States,Department of Biological Sciences, 319 Stadium Drive, Tallahassee, FL 32306, United States,Corresponding author at: Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States
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8
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Bepler T, Borst AJ, Bouvette J, Cannone G, Chen S, Cheng A, Cheng A, Fan Q, Grollios F, Gupta H, Gupta M, Humphreys T, Kim PT, Kuang H, Li Y, Noble AJ, Punjani A, Rice WJ, Oscar S Sorzano C, Stagg SM, Strauss J, Yu L, Carragher B, Potter CS. Smart data collection for CryoEM. J Struct Biol 2022; 214:107913. [PMID: 36341954 DOI: 10.1016/j.jsb.2022.107913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/29/2022] [Accepted: 10/23/2022] [Indexed: 11/06/2022]
Abstract
This report provides an overview of the discussions, presentations, and consensus thinking from the Workshop on Smart Data Collection for CryoEM held at the New York Structural Biology Center on April 6-7, 2022. The goal of the workshop was to address next generation data collection strategies that integrate machine learning and real-time processing into the workflow to reduce or eliminate the need for operator intervention.
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Affiliation(s)
| | - Andrew J Borst
- University of Washington, Institute for Protein Design, Seattle, WA, USA
| | - Jonathan Bouvette
- National Institute of Environmental Health Sciences, NIH, Durham, NC, USA
| | - Giuseppe Cannone
- Laboratory for Molecular Biology, Medical Research Council, Cambridge, England
| | - Songye Chen
- California Institute of Technology, Pasadena, CA, USA
| | - Anchi Cheng
- New York Structural Biology Center, New York, NY, USA
| | - Ao Cheng
- Northwestern University, Evanston, IL, USA
| | - Quanfu Fan
- MIT-IBM Watson AI Lab, Cambridge, MA, USA
| | | | - Harshit Gupta
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Meghna Gupta
- University of California at San Francisco, San Francisco, CA, USA
| | | | - Paul T Kim
- New York Structural Biology Center, New York, NY, USA
| | - Huihui Kuang
- New York Structural Biology Center, New York, NY, USA
| | - Yilai Li
- University of Michigan, Ann Arbor, MI, USA
| | - Alex J Noble
- New York Structural Biology Center, New York, NY, USA
| | | | - William J Rice
- New York University School of Medicine, New York, NY, USA
| | | | | | - Joshua Strauss
- University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lingbo Yu
- ThermoFisher Scientific, Eindhoven, The Netherlands
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Abstract
![]()
Adeno-associated
virus (AAV) has a single-stranded DNA genome encapsidated
in a small icosahedrally symmetric protein shell with 60 subunits.
AAV is the leading delivery vector in emerging gene therapy treatments
for inherited disorders, so its structure and molecular interactions
with human hosts are of intense interest. A wide array of electron
microscopic approaches have been used to visualize the virus and its
complexes, depending on the scientific question, technology available,
and amenability of the sample. Approaches range from subvolume tomographic
analyses of complexes with large and flexible host proteins to detailed
analysis of atomic interactions within the virus and with small ligands
at resolutions as high as 1.6 Å. Analyses have led to the reclassification
of glycan receptors as attachment factors, to structures with a new-found
receptor protein, to identification of the epitopes of antibodies,
and a new understanding of possible neutralization mechanisms. AAV
is now well-enough characterized that it has also become a model system
for EM methods development. Heralding a new era, cryo-EM is now also
being deployed as an analytic tool in the process development and
production quality control of high value pharmaceutical biologics,
namely AAV vectors.
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Affiliation(s)
- Scott M Stagg
- Department of Biological Sciences, Florida State University, Tallahassee, Florida 32306, United States.,Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
| | - Craig Yoshioka
- Department of Biomedical Engineering, Oregon Health & Science University, Portland Oregon 97239, United States
| | - Omar Davulcu
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354, United States
| | - Michael S Chapman
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
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10
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Mehrani A, Stagg SM. Probing intracellular vesicle trafficking and membrane remodelling by cryo-EM. J Struct Biol 2022; 214:107836. [PMID: 35101600 PMCID: PMC8923612 DOI: 10.1016/j.jsb.2022.107836] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/07/2022] [Accepted: 01/24/2022] [Indexed: 11/25/2022]
Abstract
Protein transport between the membranous compartments of the eukaryotic cells is mediated by the constant fission and fusion of the membrane-bounded vesicles from a donor to an acceptor membrane. While there are many membrane remodelling complexes in eukaryotes, COPII, COPI, and clathrin-coated vesicles are the three principal classes of coat protein complexes that participate in vesicle trafficking in the endocytic and secretory pathways. These vesicle-coat proteins perform two key functions: deforming lipid bilayers into vesicles and encasing selective cargoes. The three trafficking complexes share some commonalities in their structural features but differ in their coat structures, mechanisms of cargo sorting, vesicle formation, and scission. While the structures of many of the proteins involved in vesicle formation have been determined in isolation by X-ray crystallography, elucidating the proteins' structures together with the membrane is better suited for cryogenic electron microscopy (cryo-EM). In recent years, advances in cryo-EM have led to solving the structures and mechanisms of several vesicle trafficking complexes and associated proteins.
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Affiliation(s)
- Atousa Mehrani
- Department of Chemistry and Biochemistry, Florida State University
| | - Scott M. Stagg
- Department of Biological Sciences, Florida State University,Institute of Molecular Biophysics, Florida State University
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11
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Paraan M, Mendez J, Sharum S, Kurtin D, He H, Stagg SM. The structures of natively assembled clathrin-coated vesicles. Sci Adv 2020; 6:eaba8397. [PMID: 32743076 PMCID: PMC7375819 DOI: 10.1126/sciadv.aba8397] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 06/05/2020] [Indexed: 05/19/2023]
Abstract
Clathrin-coated vesicles mediate trafficking of proteins and nutrients in the cell and between organelles. Proteins included in the clathrin-coated vesicles (CCVs) category include clathrin heavy chain (CHC), clathrin light chain (CLC), and a variety of adaptor protein complexes. Much is known about the structures of the individual CCV components, but data are lacking about the structures of the fully assembled complexes together with membrane and in complex with cargo. Here, we determined the structures of natively assembled CCVs in a variety of geometries. We show that the adaptor β2 appendages crosslink adjacent CHC β-propellers and that the appendage densities are enriched in CCV hexagonal faces. We resolve how adaptor protein 2 and other associated factors in hexagonal faces form an assembly hub with an extensive web of interactions between neighboring β-propellers and propose a structural model that explains how adaptor binding can direct the formation of pentagonal and hexagonal faces.
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Affiliation(s)
- Mohammadreza Paraan
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Joshua Mendez
- Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA
| | - Savanna Sharum
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Danielle Kurtin
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Huan He
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Scott M. Stagg
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, USA
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12
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Gao Y, Guo C, Watzlawik JO, Randolph PS, Lee EJ, Huang D, Stagg SM, Zhou HX, Rosenberry TL, Paravastu AK. Out-of-Register Parallel β-Sheets and Antiparallel β-Sheets Coexist in 150-kDa Oligomers Formed by Amyloid-β(1-42). J Mol Biol 2020; 432:4388-4407. [PMID: 32470558 DOI: 10.1016/j.jmb.2020.05.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/17/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022]
Abstract
We present solid-state NMR measurements of β-strand secondary structure and inter-strand organization within a 150-kDa oligomeric aggregate of the 42-residue variant of the Alzheimer's amyloid-β peptide (Aβ(1-42)). We build upon our previous report of a β-strand spanned by residues 30-42, which arranges into an antiparallel β-sheet. New results presented here indicate that there is a second β-strand formed by residues 11-24. Contrary to expectations, NMR data indicate that this second β-strand is organized into a parallel β-sheet despite the co-existence of an antiparallel β-sheet in the same structure. In addition, the in-register parallel β-sheet commonly observed for amyloid fibril structure does not apply to residues 11-24 in the 150-kDa oligomer. Rather, we present evidence for an inter-strand registry shift of three residues that likely alternate in direction between adjacent molecules along the β-sheet. We corroborated this unexpected scheme for β-strand organization using multiple two-dimensional NMR and 13C-13C dipolar recoupling experiments. Our findings indicate a previously unknown assembly pathway and inspire a suggestion as to why this aggregate does not grow to larger sizes.
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Affiliation(s)
- Yuan Gao
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Cong Guo
- Department of Physics and International Centre for Quantum and Molecular Structures, Shanghai University, 99 Shangda Road, Shanghai, China
| | - Jens O Watzlawik
- Departments of Neuroscience and Pharmacology, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Peter S Randolph
- Institute of Molecular Biophysics, Florida State University, Tallahasse, FL 32306, USA
| | - Elizabeth J Lee
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Danting Huang
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahasse, FL 32306, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Huan-Xiang Zhou
- Department of Chemistry and Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Terrone L Rosenberry
- Departments of Neuroscience and Pharmacology, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Anant K Paravastu
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA.
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13
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Randolph PS, Stagg SM. Reconstruction of Average Subtracted Tubular Regions (RASTR) enables structure determination of tubular filaments by cryo-EM. J Struct Biol X 2020; 4:100023. [PMID: 32647826 PMCID: PMC7337063 DOI: 10.1016/j.yjsbx.2020.100023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 02/14/2020] [Accepted: 03/04/2020] [Indexed: 01/17/2023]
Abstract
Tubules (filaments, membrane tubules, etc) that stray from perfect symmetry or have decorations can be difficult to process. New method Reconstruction of Average Subtracted Tubular Regions (RASTR), provides a way to isolate small areas of tubular architecture. Upweighted and masked areas can be treated as single particles and the structure can be resolved using conventional refinement. Successfully reconstructed protein filaments and membrane tubule decorations.
As the field of electron microscopy advances, the increasing complexity of samples being produced demand more involved processing methods. In this study, we have developed a new processing method for generating 3D reconstructions of tubular structures. Tubular biomolecules are common throughout many cellular processes and are appealing targets for biophysical research. Processing of tubules with helical symmetry is relatively straightforward for electron microscopy if the helical parameters are known, but tubular structures that deviate from helical symmetry (asymmetrical components, local but no global order, etc) present myriad issues. Here we present a new processing technique called Reconstruction of Average Subtracted Tubular Regions (RASTR), which was developed to reconstruct tubular structures without applying symmetry. We explain the RASTR approach and quantify its performance using three examples: a simulated symmetrical tubular filament, a symmetrical tubular filament from cryo-EM data, and a membrane tubule coated with locally ordered but not globally ordered proteins.
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Affiliation(s)
- Peter S Randolph
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.,Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
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14
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Zhang Y, Sui X, Stagg SM, Zhang J. FTIP - An Accurate and Efficient Method for Global Protein Surface Comparison. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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15
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Paraan M, Stagg SM. Cryo-EM of Intact Clathrin-Coated Vesicles Reveals Adaptor Distribution and Novel Interactions Between Subunits. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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16
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Slosarek EL, Schuh AL, Pustova I, Johnson A, Bird J, Johnson M, Frankel EB, Bhattacharya N, Hanna MG, Burke JE, Ruhl DA, Quinney K, Block S, Peotter JL, Chapman ER, Sheets MD, Butcher SE, Stagg SM, Audhya A. Pathogenic TFG Mutations Underlying Hereditary Spastic Paraplegia Impair Secretory Protein Trafficking and Axon Fasciculation. Cell Rep 2020; 24:2248-2260. [PMID: 30157421 PMCID: PMC6152936 DOI: 10.1016/j.celrep.2018.07.081] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 06/30/2018] [Accepted: 07/25/2018] [Indexed: 02/07/2023] Open
Abstract
Length-dependent axonopathy of the corticospinal tract causes lower limb spasticity and is characteristic of several neurological disorders, including hereditary spastic paraplegia (HSP) and amyotrophic lateral sclerosis. Mutations in Trk-fused gene (TFG) have been implicated in both diseases, but the pathomechanisms by which these alterations cause neuropathy remain unclear. Here, we biochemically and genetically define the impact of a mutation within the TFG coiled-coil domain, which underlies earlyonset forms of HSP. We find that the TFG (p.R106C) mutation alters compaction of TFG ring complexes, which play a critical role in the export of cargoes from the endoplasmic reticulum (ER). Using CRISPR-mediated genome editing, we engineered human stem cells that express the mutant form of TFG at endogenous levels and identified specific defects in secretion from the ER and axon fasciculation following neuronal differentiation. Together, our data highlight a key role for TFG-mediated protein transport in the pathogenesis of HSP. Slosarek et al. demonstrate that pathological mutations in TFG, which underlie various forms of neurodegenerative disease, impair secretory protein transport from the endoplasmic reticulum and compromise the ability of axons to self-associate. These findings highlight a critical function for the early secretory pathway in neuronal maintenance.
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Affiliation(s)
- Erin L Slosarek
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Amber L Schuh
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Iryna Pustova
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Adam Johnson
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Jennifer Bird
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Matthew Johnson
- Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - E B Frankel
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Nilakshee Bhattacharya
- Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Michael G Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Jordan E Burke
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - David A Ruhl
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Kyle Quinney
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Samuel Block
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Jennifer L Peotter
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Michael D Sheets
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA
| | - Samuel E Butcher
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, 440 Henry Mall, Madison, WI 53706, USA.
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17
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Nosrati M, Dey D, Mehrani A, Strassler SE, Zelinskaya N, Hoffer ED, Stagg SM, Dunham CM, Conn GL. Functionally critical residues in the aminoglycoside resistance-associated methyltransferase RmtC play distinct roles in 30S substrate recognition. J Biol Chem 2019; 294:17642-17653. [PMID: 31594862 DOI: 10.1074/jbc.ra119.011181] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/03/2019] [Indexed: 11/06/2022] Open
Abstract
Methylation of the small ribosome subunit rRNA in the ribosomal decoding center results in exceptionally high-level aminoglycoside resistance in bacteria. Enzymes that methylate 16S rRNA on N7 of nucleotide G1405 (m7G1405) have been identified in both aminoglycoside-producing and clinically drug-resistant pathogenic bacteria. Using a fluorescence polarization 30S-binding assay and a new crystal structure of the methyltransferase RmtC at 3.14 Å resolution, here we report a structure-guided functional study of 30S substrate recognition by the aminoglycoside resistance-associated 16S rRNA (m7G1405) methyltransferases. We found that the binding site for these enzymes in the 30S subunit directly overlaps with that of a second family of aminoglycoside resistance-associated 16S rRNA (m1A1408) methyltransferases, suggesting that both groups of enzymes may exploit the same conserved rRNA tertiary surface for docking to the 30S. Within RmtC, we defined an N-terminal domain surface, comprising basic residues from both the N1 and N2 subdomains, that directly contributes to 30S-binding affinity. In contrast, additional residues lining a contiguous adjacent surface on the C-terminal domain were critical for 16S rRNA modification but did not directly contribute to the binding affinity. The results from our experiments define the critical features of m7G1405 methyltransferase-substrate recognition and distinguish at least two distinct, functionally critical contributions of the tested enzyme residues: 30S-binding affinity and stabilizing a binding-induced 16S rRNA conformation necessary for G1405 modification. Our study sets the scene for future high-resolution structural studies of the 30S-methyltransferase complex and for potential exploitation of unique aspects of substrate recognition in future therapeutic strategies.
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Affiliation(s)
- Meisam Nosrati
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Debayan Dey
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Atousa Mehrani
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306
| | - Sarah E Strassler
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Natalia Zelinskaya
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Eric D Hoffer
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306
| | - Christine M Dunham
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Graeme L Conn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
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18
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Stagg SM. Quality versus resolution in cryo-EM maps. Acta Crystallogr A Found Adv 2019. [DOI: 10.1107/s0108767319095990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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19
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Meyer NL, Hu G, Davulcu O, Xie Q, Noble AJ, Yoshioka C, Gingerich DS, Trzynka A, David L, Stagg SM, Chapman MS. Structure of the gene therapy vector, adeno-associated virus with its cell receptor, AAVR. eLife 2019; 8:e44707. [PMID: 31115336 PMCID: PMC6561701 DOI: 10.7554/elife.44707] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/22/2019] [Indexed: 11/26/2022] Open
Abstract
Adeno-associated virus (AAV) vectors are preeminent in emerging clinical gene therapies. Generalizing beyond the most tractable genetic diseases will require modulation of cell specificity and immune neutralization. Interactions of AAV with its cellular receptor, AAVR, are key to understanding cell-entry and trafficking with the rigor needed to engineer tissue-specific vectors. Cryo-electron tomography shows ordered binding of part of the flexible receptor to the viral surface, with distal domains in multiple conformations. Regions of the virus and receptor in close physical proximity can be identified by cross-linking/mass spectrometry. Cryo-electron microscopy with a two-domain receptor fragment reveals the interactions at 2.4 Å resolution. AAVR binds between AAV's spikes on a plateau that is conserved, except in one clade whose structure is AAVR-incompatible. AAVR's footprint overlaps the epitopes of several neutralizing antibodies, prompting a re-evaluation of neutralization mechanisms. The structure provides a roadmap for experimental probing and manipulation of viral-receptor interactions.
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Affiliation(s)
- Nancy L Meyer
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
| | - Guiqing Hu
- Institute Molecular BiophysicsFlorida State UniversityTallahasseeUnited States
| | - Omar Davulcu
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
| | - Qing Xie
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
| | - Alex J Noble
- Institute Molecular BiophysicsFlorida State UniversityTallahasseeUnited States
| | - Craig Yoshioka
- OHSU Center for Spatial Systems BiomedicinePortlandUnited States
| | - Drew S Gingerich
- OHSU Center for Spatial Systems BiomedicinePortlandUnited States
| | - Andrew Trzynka
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
| | - Larry David
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
| | - Scott M Stagg
- Institute Molecular BiophysicsFlorida State UniversityTallahasseeUnited States
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeUnited States
| | - Michael Stewart Chapman
- Department of Biochemistry and Molecular BiologyOregon Health and Science UniversityPortlandUnited States
- Department of BiochemistryUniversity of MissouriColumbiaUnited States
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20
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Mendez JH, Stagg SM. Characterization of the DE64 Direct Electron Detector. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.3086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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21
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Stagg SM, Mendez JH. Throughput and Resolution with a Next Generation Direct Detector. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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22
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Mendez JH, Stagg SM. Assessing the quality of single particle reconstructions by atomic model building. J Struct Biol 2018; 204:276-282. [PMID: 30213768 PMCID: PMC6201253 DOI: 10.1016/j.jsb.2018.09.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 09/05/2018] [Accepted: 09/08/2018] [Indexed: 10/28/2022]
Abstract
The 2015/2016 Map Challenge challenged cryo-EM practitioners to process a series of publicly available cryo-EM datasets. As part of the challenge, metrics needed to be developed to assess and compare the quality of the different map submissions. The most common metric for assessing maps is determining the resolution by Fourier shell correlation (FSC), but there are well known instances where the resolution can be misleading. In this manuscript, we present a new approach for assessing the quality of a map by determining the map "modelability" rather than on resolution. We used the automated map tracing and modeling algorithms in Rosetta to generate populations of models, and then compared the populations between different map entries by the Rosetta score, RMSD to a reference model provided by the map challenge, and by pair-wise RMSDs between different models in the population. These metrics were used to determine statistically significant rankings for the map challengers for each dataset. The rankings revealed inconsistencies between the resolution by FSC, emphasized the importance of the interplay between number of particles contributing to a map and map quality, and revealed the importance of software familiarity on single particle reconstruction results. However, because multiple variables changed between map entries, it was challenging to derive best practices from the map challenge results.
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Affiliation(s)
- Joshua H Mendez
- Department of Physics, 77 Chieftan Way, Tallahassee, FL 32306, United States
| | - Scott M Stagg
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States; Department of Chemistry and Biochemistry, 95 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States.
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23
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Paraan M, Bhattacharya N, Uversky VN, Stagg SM. Flexibility of the Sec13/31 cage is influenced by the Sec31 C-terminal disordered domain. J Struct Biol 2018; 204:250-260. [PMID: 30172710 DOI: 10.1016/j.jsb.2018.08.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 08/23/2018] [Accepted: 08/29/2018] [Indexed: 01/30/2023]
Abstract
In COPII mediated vesicle formation, Sec13/Sec31 heterotetramers play a role in organizing the membranes into a spherical vesicle. There they oligomerize into a cage that interacts with the other COPII proteins to direct vesicle formation and concentrate cargo into a bud. In this role they must be flexible to accommodate different sizes and shapes of cargo, but also have elements that provide rigidity to help deform the membrane. Here we characterize the influence the C-terminal disordered region of Sec31 has on cage flexibility and rigidity. After deleting this region (residues 820-1220), we characterized Sec13/Sec31ΔC heterotetramers biophysically and structurally through cryo-EM. Our results show that Sec13/31ΔC self-assembles into canonical cuboctahedral cages in vitro at buffer conditions similar to wild type. The distribution of cage sizes indicated that unlike the wild type, Sec13/31ΔC cages have a more homogeneous geometry. However, the structure of cuboctahedrons exhibited more conformational heterogeneity than wild type. Through localized reconstruction of cage vertices and molecular dynamics flexible fitting we found a new hinge for the flexing of Sec31 β-propeller domain and more flexibility of the previously known hinge. Together, these results show that the C-terminal region of Sec31 regulates the flexing of other domains such that flexibility and rigidity are not compromised during transport of large and/or asymmetric cargo.
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Affiliation(s)
- Mohammadreza Paraan
- Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306, USA
| | - Nilakshee Bhattacharya
- Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA; Institute for Biological Instrumentation of the Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia
| | - Scott M Stagg
- Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306, USA; Department of Chemistry and Biochemistry, 95 Chieftain Way, Florida State University, Tallahassee, FL 32306, USA.
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24
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Abstract
The 3DEM map challenge provided an opportunity to test different algorithms and workflows for processing single particle cryo-EM data. We were interested in testing whether we could use the standard Appion workflow with minimal manual intervention to achieve similar or better resolution than other challengers. Another question we were interested in testing was what the influence of particle sorting and elimination would be on the resolution and quality of 3D reconstructions. Since apoferritin is historically a challenging particle for single particle reconstruction and the authors of the original map challenge data used only a fraction of the particles present in the dataset, we focused on the apoferritin dataset for our entry. We submitted a 3.7 Å map from 25,844 particles and a 3.6 Å map from 53,334 particles and after assessment were among the best of the apoferritin maps that were submitted. Here we present the details of our reconstruction strategy and compare our strategy to that of another high-scoring apoferritin map. Altogether, our results suggest that for a relatively conformationally homogeneous particle like apoferritin, including as many particles as possible after elimination of junk leads to the highest resolution, and the choice of parameters for custom mask creation can lead to subtle but significant changes in the resolution of 3D reconstructions.
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Affiliation(s)
- Scott M Stagg
- Institute of Molecular Biophysics, 91 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States; Department of Chemistry and Biochemistry, 95 Chieftain Way, Florida State University, Tallahassee, FL 32306, United States.
| | - Joshua H Mendez
- Department of Physics, 77 Chieftan Way, Tallahassee, FL 32306, United States
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25
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Kizziah JL, Manning KA, Dearborn AD, Wall EA, Klenow L, Hill RLL, Spilman MS, Stagg SM, Christie GE, Dokland T. Cleavage and Structural Transitions during Maturation of Staphylococcus aureus Bacteriophage 80α and SaPI1 Capsids. Viruses 2017; 9:v9120384. [PMID: 29258203 PMCID: PMC5744158 DOI: 10.3390/v9120384] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/08/2017] [Accepted: 12/15/2017] [Indexed: 12/21/2022] Open
Abstract
In the tailed bacteriophages, DNA is packaged into spherical procapsids, leading to expansion into angular, thin-walled mature capsids. In many cases, this maturation is accompanied by cleavage of the major capsid protein (CP) and other capsid-associated proteins, including the scaffolding protein (SP) that serves as a chaperone for the assembly process. Staphylococcus aureus bacteriophage 80α is capable of high frequency mobilization of mobile genetic elements called S. aureus pathogenicity islands (SaPIs), such as SaPI1. SaPI1 redirects the assembly pathway of 80α to form capsids that are smaller than those normally made by the phage alone. Both CP and SP of 80α are N-terminally processed by a host-encoded protease, Prp. We have analyzed phage mutants that express pre-cleaved or uncleavable versions of CP or SP, and show that the N-terminal sequence in SP is absolutely required for assembly, but does not need to be cleaved in order to produce viable capsids. Mutants with pre-cleaved or uncleavable CP display normal viability. We have used cryo-EM to solve the structures of mature capsids from an 80α mutant expressing uncleavable CP, and from wildtype SaPI1. Comparisons with structures of 80α and SaPI1 procapsids show that capsid maturation involves major conformational changes in CP, consistent with a release of the CP N-arm by SP. The hexamers reorganize during maturation to accommodate the different environments in the 80α and SaPI1 capsids.
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Affiliation(s)
- James L Kizziah
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Keith A Manning
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Altaira D Dearborn
- Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, The National Institutes of Health, Bethesda, MD 20892, USA.
| | - Erin A Wall
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
| | - Laura Klenow
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
| | - Rosanne L L Hill
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Michael S Spilman
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
| | - Gail E Christie
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
| | - Terje Dokland
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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26
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Tian S, Yu G, He H, Zhao Y, Liu P, Marshall AG, Demeler B, Stagg SM, Li H. Pih1p-Tah1p Puts a Lid on Hexameric AAA+ ATPases Rvb1/2p. Structure 2017; 25:1519-1529.e4. [PMID: 28919439 PMCID: PMC6625358 DOI: 10.1016/j.str.2017.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/11/2017] [Accepted: 08/07/2017] [Indexed: 11/21/2022]
Abstract
The Saccharomyces cerevisiae (Sc) R2TP complex affords an Hsp90-mediated and nucleotide-driven chaperone activity to proteins of small ribonucleoprotein particles (snoRNPs). The current lack of structural information on the ScR2TP complex, however, prevents a mechanistic understanding of this biological process. We characterized the structure of the ScR2TP complex made up of two AAA+ ATPases, Rvb1/2p, and two Hsp90 binding proteins, Tah1p and Pih1p, and its interaction with the snoRNP protein Nop58p by a combination of analytical ultracentrifugation, isothermal titration calorimetry, chemical crosslinking, hydrogen-deuterium exchange, and cryoelectron microscopy methods. We find that Pih1p-Tah1p interacts with Rvb1/2p cooperatively through the nucleotide-sensitive domain of Rvb1/2p. Nop58p further binds Pih1p-Tahp1 on top of the dome-shaped R2TP. Consequently, nucleotide binding releases Pih1p-Tah1p from Rvb1/2p, which offers a mechanism for nucleotide-driven binding and release of snoRNP intermediates.
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Affiliation(s)
- Shaoxiong Tian
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Ge Yu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Huan He
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Yu Zhao
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Peilu Liu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Alan G Marshall
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; Ion Cyclotron Resonance Program, The National High Magnetic Field Laboratory, Tallahassee, FL 32310, USA
| | - Borries Demeler
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Hong Li
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
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27
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Xie Q, Spear JM, Noble AJ, Sousa DR, Meyer NL, Davulcu O, Zhang F, Linhardt RJ, Stagg SM, Chapman MS. The 2.8 Å Electron Microscopy Structure of Adeno-Associated Virus-DJ Bound by a Heparinoid Pentasaccharide. Mol Ther Methods Clin Dev 2017; 5:1-12. [PMID: 28480299 PMCID: PMC5415311 DOI: 10.1016/j.omtm.2017.02.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 02/22/2017] [Indexed: 01/24/2023]
Abstract
Atomic structures of adeno-associated virus (AAV)-DJ, alone and in complex with fondaparinux, have been determined by cryoelectron microscopy at 3 Å resolution. The gene therapy vector, AAV-DJ, is a hybrid of natural serotypes that was previously derived by directed evolution, selecting for hepatocyte entry and resistance to neutralization by human serum. The structure of AAV-DJ differs from that of parental serotypes in two regions where neutralizing antibodies bind, so immune escape appears to have been the primary driver of AAV-DJ's directed evolution. Fondaparinux is an analog of cell surface heparan sulfate to which several AAVs bind during entry. Fondaparinux interacts with viral arginines at a known heparin binding site, without the large conformational changes whose presence was controversial in low-resolution imaging of AAV2-heparin complexes. The glycan density suggests multi-modal binding that could accommodate sequence variation and multivalent binding along a glycan polymer, consistent with a role in attachment, prior to more specific interactions with a receptor protein mediating entry.
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Affiliation(s)
- Qing Xie
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, USA
| | - John M. Spear
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306-4380, USA
| | - Alex J. Noble
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306-4380, USA
| | - Duncan R. Sousa
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306-4380, USA
| | - Nancy L. Meyer
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, USA
| | - Omar Davulcu
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, USA
| | - Fuming Zhang
- Departments of Chemical and Biological Engineering, Chemistry, and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Robert J. Linhardt
- Departments of Chemical and Biological Engineering, Chemistry, and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Scott M. Stagg
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306-4380, USA
| | - Michael S. Chapman
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, USA
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Tian S, Yu G, He H, Liu P, Marshall AG, Demeler B, Stagg SM, Li H. Structure and function of a snoRNP maturation complex. Acta Crystallogr A Found Adv 2017. [DOI: 10.1107/s0108767317097008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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29
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Lowry TW, Hariri H, Prommapan P, Kusi-Appiah A, Vafai N, Bienkiewicz EA, Van Winkle DH, Stagg SM, Lenhert S. Quantification of Protein-Induced Membrane Remodeling Kinetics In Vitro with Lipid Multilayer Gratings. Small 2016; 12:506-15. [PMID: 26649649 PMCID: PMC4843995 DOI: 10.1002/smll.201502398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/28/2015] [Indexed: 05/08/2023]
Abstract
The dynamic self-organization of lipids in biological systems is a highly regulated process that enables the compartmentalization of living systems at micro- and nanoscopic scales. Consequently, quantitative methods for assaying the kinetics of supramolecular remodeling such as vesicle formation from planar lipid bilayers or multilayers are needed to understand cellular self-organization. Here, a new nanotechnology-based method for quantitative measurements of lipid-protein interactions is presented and its suitability for quantifying the membrane binding, inflation, and budding activity of the membrane-remodeling protein Sar1 is demonstrated. Lipid multilayer gratings are printed onto surfaces using nanointaglio and exposed to Sar1, resulting in the inflation of lipid multilayers into unilamellar structures, which can be observed in a label-free manner by monitoring the diffracted light. Local variations in lipid multilayer volume on the surface is used to vary substrate availability in a microarray format. A quantitative model is developed that allows quantification of binding affinity (K D ) and kinetics (kon and koff ). Importantly, this assay is uniquely capable of quantifying membrane remodeling. Upon Sar1-induced inflation of single bilayers from surface supported multilayers, the semicylindrical grating lines are observed to remodel into semispherical buds when a critical radius of curvature is reached.
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Affiliation(s)
- Troy W. Lowry
- Department of Physics, Florida State University, Tallahassee, FL 32306-4350, USA
| | - Hanaa Hariri
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Plengchart Prommapan
- Department of Physics, Florida State University, Tallahassee, FL 32306-4350, USA
| | - Aubrey Kusi-Appiah
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA
| | - Nicholas Vafai
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA
| | - Ewa A. Bienkiewicz
- Department of Biomedical Science, College of Medicine, Florida State University, Tallahassee, FL 32306-4300, USA
| | - David H. Van Winkle
- Department of Physics, Florida State University, Tallahassee, FL 32306-4350, USA
| | - Scott M. Stagg
- Institute of Molecular Biophysics and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4380, USA
| | - Steven Lenhert
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4370, USA
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Abstract
A microfluidic platform is presented for preparing negatively stained grids for use in transmission electron microscopy (EM). The microfluidic device is composed of glass etched with readily fabricated features that facilitate the extraction of the grid poststaining and maintains the integrity of the sample. Utilization of this device simultaneously reduced environmental contamination on the grids and improved the homogeneity of the heavy metal stain needed to enhance visualization of biological specimens as compared to conventionally prepared EM grids. This easy-to-use EM grid preparation device provides the basis for future developments of systems with more integrated features, which will allow for high-throughput and dynamic structural biology studies.
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Affiliation(s)
- Nikita Mukhitov
- Department of Chemistry and Biochemistry, Florida State University , 95 Chieftain Way, Tallahassee, Florida 32306, United States
| | - John M Spear
- Institute of Molecular Biophysics, Florida State University , 91 Chieftain Way, Tallahassee, Florida 32306, United States
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Florida State University , 95 Chieftain Way, Tallahassee, Florida 32306, United States.,Institute of Molecular Biophysics, Florida State University , 91 Chieftain Way, Tallahassee, Florida 32306, United States
| | - Michael G Roper
- Department of Chemistry and Biochemistry, Florida State University , 95 Chieftain Way, Tallahassee, Florida 32306, United States
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31
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Noble AJ, Stagg SM. Automated batch fiducial-less tilt-series alignment in Appion using Protomo. J Struct Biol 2015; 192:270-8. [PMID: 26455557 PMCID: PMC4633401 DOI: 10.1016/j.jsb.2015.10.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/30/2015] [Accepted: 10/01/2015] [Indexed: 01/06/2023]
Abstract
The field of electron tomography has benefited greatly from manual and semi-automated approaches to marker-based tilt-series alignment that have allowed for the structural determination of multitudes of in situ cellular structures as well as macromolecular structures of individual protein complexes. The emergence of complementary metal-oxide semiconductor detectors capable of detecting individual electrons has enabled the collection of low dose, high contrast images, opening the door for reliable correlation-based tilt-series alignment. Here we present a set of automated, correlation-based tilt-series alignment, contrast transfer function (CTF) correction, and reconstruction workflows for use in conjunction with the Appion/Leginon package that are primarily targeted at automating structure determination with cryogenic electron microscopy.
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Affiliation(s)
- Alex J Noble
- Department of Physics, 77 Chieftan Way, Florida State University, Tallahassee, FL 32306, USA
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, 95 Chieftain Way, Florida State University, Tallahassee, FL 32306, USA; Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306, USA.
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32
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Spear JM, Noble AJ, Xie Q, Sousa DR, Chapman MS, Stagg SM. The influence of frame alignment with dose compensation on the quality of single particle reconstructions. J Struct Biol 2015; 192:196-203. [PMID: 26391007 DOI: 10.1016/j.jsb.2015.09.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/15/2015] [Accepted: 09/16/2015] [Indexed: 12/21/2022]
Abstract
As direct electron detection devices in cryo-electron microscopy become ubiquitous, the field is now ripe for new developments in image analysis techniques that take advantage of their increased SNR coupled with their high-throughput frame collection abilities. In approaching atomic resolution of native-like biomolecules, the accurate extraction of structural locations and orientations of side-chains from frames depends not only on the electron dose that a sample receives but also on the ability to accurately estimate the CTF. Here we use a new 2.8Å resolution structure of a recombinant gene therapy virus, AAV-DJ with Arixtra, imaged on an FEI Titan Krios with a DE-20 direct electron detector to probe new metrics including relative side-chain density and ResLog analysis for optimizing the compensation of electron beam damage and to characterize the factors that are limiting the resolution of the reconstruction. The influence of dose compensation on the accuracy of CTF estimation and particle classifiability are also presented. We show that rigorous dose compensation allows for better particle classifiability and greater recovery of structural information from negatively charged, electron-sensitive side-chains, resulting in a more accurate macromolecular model.
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Affiliation(s)
- John M Spear
- Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306-4380, United States
| | - Alex J Noble
- Department of Physics, 77 Chieftan Way, Florida State University, Tallahassee, FL 32306-4350, United States
| | - Qing Xie
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Duncan R Sousa
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306, United States
| | - Michael S Chapman
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, United States
| | - Scott M Stagg
- Institute of Molecular Biophysics, 91 Chieftan Way, Florida State University, Tallahassee, FL 32306-4380, United States; Departments of Chemistry and Biochemistry, 95 Chieftain Way, Florida State University, Tallahassee, FL 32306-4390, United States.
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33
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Noble AJ, Stagg SM. STRUCTURAL BIOLOGY. COPI gets a fancy new coat. Science 2015; 349:142-3. [PMID: 26160933 DOI: 10.1126/science.aac6537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Alex J Noble
- Department of Physics, Florida State University, 77 Chieftan Way, Tallahassee, FL 32306, USA
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL 32306, USA. Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA.
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Spear JM, Koborssy DA, Schwartz AB, Johnson AJ, Audhya A, Fadool DA, Stagg SM. Kv1.3 contains an alternative C-terminal ER exit motif and is recruited into COPII vesicles by Sec24a. BMC Biochem 2015; 16:16. [PMID: 26156069 PMCID: PMC4497498 DOI: 10.1186/s12858-015-0045-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/26/2015] [Indexed: 12/11/2022]
Abstract
Background Potassium channels play a fundamental role in resetting the resting membrane potential of excitable cells. Determining the intracellular trafficking and localization mechanisms of potassium channels provides a platform to fully characterize their maturation and functionality. Previous investigations have discovered residues or motifs that exist in their primary structure, which directly promote anterograde trafficking of nascent potassium channels. Recently, a non-conical di-acidic motif (E483/484) has been discovered in the C-terminus of the mammalian homologue of the Shaker voltage-gated potassium channel subfamily member 3 (Kv1.3), and was shown to disrupt the anterograde trafficking of Kv1.3. Results We have further investigated the intracellular trafficking requirements of Kv1.3 both in vivo and in vitro. First, three alternative C-terminal acidic residues, E443, E445, E447 were probed for their involvement within the early secretory pathway of Kv1.3. Single point (E443A, E445A, and E447A) and double point (E443A-E445A, E445A-E447A) mutations exhibited no significant changes in their endoplasmic reticulum (ER) retention. The triple point mutant E443A-E445A-E447A displayed a modest ER retention while deletion of the C-terminus showed dramatic ER retention. Second, we demonstrate in vivo the requirement for the Sec24a isoform to confer anterograde trafficking using a siRNA knockdown assay. Third, we show in vitro the association of recombinantly expressed Kv1.3 and Sec24a proteins. Conclusion These results expand upon previous studies aimed at deciphering the Kv1.3 secretory trafficking mechanisms and further show in vitro evidence of the association between Kv1.3 and the COPII cargo adaptor subunit isoform Sec24a. Electronic supplementary material The online version of this article (doi:10.1186/s12858-015-0045-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John M Spear
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
| | - Dolly Al Koborssy
- Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL, 32306, USA.
| | - Austin B Schwartz
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
| | - Adam J Johnson
- Biomolecular Chemistry, University of Wisconsin-Madison, 440 Henry Mall, Madison, WI, 53706, USA.
| | - Anjon Audhya
- Biomolecular Chemistry, University of Wisconsin-Madison, 440 Henry Mall, Madison, WI, 53706, USA.
| | - Debra A Fadool
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA. .,Program in Neuroscience, Florida State University, 1107 West Call Street, Tallahassee, FL, 32306, USA. .,Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL, 32306, USA.
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA. .,Department of Chemistry and Biochemistry, Florida State University, 91 Chieftan Way, Tallahassee, FL, 32306, USA.
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35
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Gianfelice A, Le PHB, Rigano LA, Saila S, Dowd GC, McDivitt T, Bhattacharya N, Hong W, Stagg SM, Ireton K. Host endoplasmic reticulum COPII proteins control cell-to-cell spread of the bacterial pathogen Listeria monocytogenes. Cell Microbiol 2015; 17:876-92. [PMID: 25529574 DOI: 10.1111/cmi.12409] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 12/14/2014] [Accepted: 12/15/2014] [Indexed: 12/22/2022]
Abstract
Listeria monocytogenes is a food-borne pathogen that uses actin-dependent motility to spread between human cells. Cell-to-cell spread involves the formation by motile bacteria of plasma membrane-derived structures termed 'protrusions'. In cultured enterocytes, the secreted Listeria protein InlC promotes protrusion formation by binding and inhibiting the human scaffolding protein Tuba. Here we demonstrate that protrusions are controlled by human COPII components that direct trafficking from the endoplasmic reticulum. Co-precipitation experiments indicated that the COPII proteins Sec31A and Sec13 interact directly with a Src homology 3 domain in Tuba. This interaction was antagonized by InlC. Depletion of Sec31A or Sec13 restored normal protrusion formation to a Listeria mutant lacking inlC, without affecting spread of wild-type bacteria. Genetic impairment of the COPII component Sar1 or treatment of cells with brefeldin A affected protrusions similarly to Sec31A or Sec13 depletion. These findings indicated that InlC relieves a host-mediated restriction of Listeria spread otherwise imposed by COPII. Inhibition of Sec31A, Sec13 or Sar1 or brefeldin A treatment also perturbed the structure of cell-cell junctions. Collectively, these findings demonstrate an important role for COPII in controlling Listeria spread. We propose that COPII may act by delivering host proteins that generate tension at cell junctions.
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Affiliation(s)
- Antonella Gianfelice
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Phuong H B Le
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Luciano A Rigano
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Susan Saila
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Georgina C Dowd
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Tina McDivitt
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Nilakshee Bhattacharya
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, Singapore
| | - Scott M Stagg
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Keith Ireton
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
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36
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Johnson A, Bhattacharya N, Hanna M, Pennington JG, Schuh AL, Wang L, Otegui MS, Stagg SM, Audhya A. TFG clusters COPII-coated transport carriers and promotes early secretory pathway organization. EMBO J 2015; 34:811-27. [PMID: 25586378 DOI: 10.15252/embj.201489032] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In mammalian cells, cargo-laden secretory vesicles leave the endoplasmic reticulum (ER) en route to ER-Golgi intermediate compartments (ERGIC) in a manner dependent on the COPII coat complex. We report here that COPII-coated transport carriers traverse a submicron, TFG (Trk-fused gene)-enriched zone at the ER/ERGIC interface. The architecture of TFG complexes as determined by three-dimensional electron microscopy reveals the formation of flexible, octameric cup-like structures, which are able to self-associate to generate larger polymers in vitro. In cells, loss of TFG function dramatically slows protein export from the ER and results in the accumulation of COPII-coated carriers throughout the cytoplasm. Additionally, the tight association between ER and ERGIC membranes is lost in the absence of TFG. We propose that TFG functions at the ER/ERGIC interface to locally concentrate COPII-coated transport carriers and link exit sites on the ER to ERGIC membranes. Our findings provide a new mechanism by which COPII-coated carriers are retained near their site of formation to facilitate rapid fusion with neighboring ERGIC membranes upon uncoating, thereby promoting interorganellar cargo transport.
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Affiliation(s)
- Adam Johnson
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | | | - Michael Hanna
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Janice G Pennington
- Departments of Botany and Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Amber L Schuh
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Lei Wang
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
| | - Marisa S Otegui
- Departments of Botany and Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA
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37
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Ramia NF, Spilman M, Tang L, Shao Y, Elmore J, Hale C, Cocozaki A, Bhattacharya N, Terns RM, Terns MP, Li H, Stagg SM. Essential structural and functional roles of the Cmr4 subunit in RNA cleavage by the Cmr CRISPR-Cas complex. Cell Rep 2014; 9:1610-1617. [PMID: 25482566 DOI: 10.1016/j.celrep.2014.11.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/14/2014] [Accepted: 11/05/2014] [Indexed: 10/24/2022] Open
Abstract
The Cmr complex is the multisubunit effector complex of the type III-B clustered regularly interspaced short palindromic repeats (CRISPR)-Cas immune system. The Cmr complex recognizes a target RNA through base pairing with the integral CRISPR RNA (crRNA) and cleaves the target at multiple regularly spaced locations within the complementary region. To understand the molecular basis of the function of this complex, we have assembled information from electron microscopic and X-ray crystallographic structural studies and mutagenesis of a complete Pyrococcus furiosus Cmr complex. Our findings reveal that four helically packed Cmr4 subunits, which make up the backbone of the Cmr complex, act as a platform to support crRNA binding and target RNA cleavage. Interestingly, we found a hook-like structural feature associated with Cmr4 that is likely the site of target RNA binding and cleavage. Our results also elucidate analogies in the mechanisms of crRNA and target molecule binding by the distinct Cmr type III-A and Cascade type I-E complexes.
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Affiliation(s)
- Nancy F Ramia
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Michael Spilman
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Li Tang
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Yaming Shao
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Joshua Elmore
- Departments of Biochemistry and Molecular Biology, Genetics, and Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Caryn Hale
- Departments of Biochemistry and Molecular Biology, Genetics, and Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Alexis Cocozaki
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | | | - Rebecca M Terns
- Departments of Biochemistry and Molecular Biology, Genetics, and Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Michael P Terns
- Departments of Biochemistry and Molecular Biology, Genetics, and Microbiology, University of Georgia, Athens, GA 30602, USA.
| | - Hong Li
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA.
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38
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Xie Q, Spilman M, Meyer NL, Lerch TF, Stagg SM, Chapman MS. Electron microscopy analysis of a disaccharide analog complex reveals receptor interactions of adeno-associated virus. J Struct Biol 2013; 184:129-35. [PMID: 24036405 DOI: 10.1016/j.jsb.2013.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 12/19/2022]
Abstract
Mechanistic studies of macromolecular complexes often feature X-ray structures of complexes with bound ligands. The attachment of adeno-associated virus (AAV) to cell surface glycosaminoglycans (GAGs) is an example that has not proven amenable to crystallography, because the binding of GAG analogs disrupts lattice contacts. The interactions of AAV with GAGs are of interest in mediating the cell specificity of AAV-based gene therapy vectors. Previous electron microscopy led to differing conclusions on the exact binding site and the existence of large ligand-induced conformational changes in the virus. Conformational changes are expected during cell entry, but it has remained unclear whether the electron microscopy provided evidence of their induction by GAG-binding. Taking advantage of automated data collection, careful processing and new methods of structure refinement, the structure of AAV-DJ complexed with sucrose octasulfate is determined by electron microscopy difference map analysis to 4.8Å resolution. At this higher resolution, individual sulfate groups are discernible, providing a stereochemical validation of map interpretation, and highlighting interactions with two surface arginines that have been implicated in genetic studies. Conformational changes induced by the SOS are modest and limited to the loop most directly interacting with the ligand. While the resolution attainable will depend on sample order and other factors, there are an increasing number of macromolecular complexes that can be studied by cryo-electron microscopy at resolutions beyond 5Å, for which the approaches used here could be used to characterize the binding of inhibitors and other small molecule effectors when crystallography is not tractable.
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Affiliation(s)
- Qing Xie
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health &v Science University, Portland, OR 97239-3098, USA
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39
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Sousa DR, Stagg SM, Stroupe ME. Cryo-EM structures of the actin:tropomyosin filament reveal the mechanism for the transition from C- to M-state. J Mol Biol 2013; 425:4544-55. [PMID: 24021812 DOI: 10.1016/j.jmb.2013.08.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 08/22/2013] [Accepted: 08/23/2013] [Indexed: 12/18/2022]
Abstract
Tropomyosin (Tm) is a key factor in the molecular mechanisms that regulate the binding of myosin motors to actin filaments (F-Actins) in most eukaryotic cells. This regulation is achieved by the azimuthal repositioning of Tm along the actin (Ac):Tm:troponin (Tn) thin filament to block or expose myosin binding sites on Ac. In striated muscle, including involuntary cardiac muscle, Tm regulates muscle contraction by coupling Ca(2+) binding to Tn with myosin binding to the thin filament. In smooth muscle, the switch is the posttranslational modification of the myosin. Depending on the activation state of Tn and the binding state of myosin, Tm can occupy the blocked, closed, or open position on Ac. Using native cryogenic 3DEM (three-dimensional electron microscopy), we have directly resolved and visualized cardiac and gizzard muscle Tm on filamentous Ac in the position that corresponds to the closed state. From the 8-Å-resolution structure of the reconstituted Ac:Tm filament formed with gizzard-derived Tm, we discuss two possible mechanisms for the transition from closed to open state and describe the role Tm plays in blocking myosin tight binding in the closed-state position.
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Affiliation(s)
- Duncan R Sousa
- Department of Biological Science and Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA; Department of Physiology and Biophysics, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118-2526, USA
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Noble AJ, Zhang Q, O'Donnell J, Hariri H, Bhattacharya N, Marshall AG, Stagg SM. A pseudoatomic model of the COPII cage obtained from cryo-electron microscopy and mass spectrometry. Nat Struct Mol Biol 2013; 20:167-73. [PMID: 23262493 PMCID: PMC3565055 DOI: 10.1038/nsmb.2467] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/09/2012] [Indexed: 12/23/2022]
Abstract
COPII vesicles transport proteins from the endoplasmic reticulum to the Golgi apparatus. Previous COPII-cage cryo-EM structures lacked the resolution necessary to determine the residues of Sec13 and Sec31 that mediate assembly and flexibility of the COPII cage. Here we present a 12-Å structure of the human COPII cage, where the tertiary structure of Sec13 and Sec31 is clearly identifiable. We employ this structure and a homology model of the Sec13-Sec31 complex to create a reliable pseudoatomic model of the COPII cage. We combined this model with hydrogen/deuterium-exchange MS analysis to characterize four distinct contact regions at the vertices of the COPII cage. Furthermore, we found that the two-fold symmetry of the Sec31 dimeric region in Sec13-Sec31 is broken upon cage formation and that the resulting hinge is essential to form the proper edge geometry in COPII cages.
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Affiliation(s)
- Alex J Noble
- Department of Physics, Florida State University, Tallahassee, Florida, USA
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Lerch TF, O’Donnell JK, Meyer NL, Xie Q, Taylor KA, Stagg SM, Chapman MS. Structure of AAV-DJ, a retargeted gene therapy vector: cryo-electron microscopy at 4.5 Å resolution. Structure 2012; 20:1310-20. [PMID: 22727812 PMCID: PMC3418430 DOI: 10.1016/j.str.2012.05.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/10/2012] [Accepted: 05/11/2012] [Indexed: 12/19/2022]
Abstract
AAV-DJ, a leading candidate vector for liver gene therapy, was created through random homologous recombination followed by directed evolution, selecting for in vivo liver tropism and resistance to in vitro immune neutralization. Here, the 4.5 Å resolution cryo-EM structure is determined for the engineered AAV vector, revealing structural features that illuminate its phenotype. The heparan sulfate receptor-binding site is little changed from AAV-2, and heparin-binding affinity is similar. A loop that is antigenic in other serotypes has a unique conformation in AAV-DJ that would conflict with the binding of an AAV-2 neutralizing monoclonal antibody. This is consistent with increased resistance to neutralization by human polyclonal sera, raising the possibility that changed tropism may be a secondary effect of altered immune interactions. The reconstruction exemplifies analysis of fine structural changes and the potential of cryo-EM, in favorable cases, to characterize mutant or ligand-bound complexes.
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Affiliation(s)
- Thomas F. Lerch
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Jason K. O’Donnell
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
| | - Nancy L. Meyer
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Qing Xie
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kenneth A. Taylor
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Scott M. Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Michael S. Chapman
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
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Bhattacharya N, O Donnell J, Stagg SM. The structure of the Sec13/31 COPII cage bound to Sec23. J Mol Biol 2012; 420:324-34. [PMID: 22543240 DOI: 10.1016/j.jmb.2012.04.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 04/03/2012] [Accepted: 04/23/2012] [Indexed: 02/03/2023]
Abstract
Structural studies have revealed some of the organizing principles and mechanisms involved in the assembly of the COPII coat including the location of the Sec23/24 adapter layer. Previous studies, however, were unable to unambiguously determine the positions of Sec23 and Sec24 in the coat. Here, we have determined a cryogenic electron microscopic structure of Sec13/31 together with Sec23. Electron tomography revealed that the binding of Sec23 induces Sec13/31 to form a variety of different geometries including a cuboctahedron, as was previously characterized for Sec13/31 alone. Single-particle reconstruction of the Sec13/31-23 cuboctahedra revealed that the binding of Sec23 induces a conformational change in Sec13/31, resulting in a more extended conformation. Docking Sec23 crystal structures into the electron microscopy map suggested that Sec24 projects its cargo binding surface out into the large open faces of the coat. These results have implications for the mechanisms by which COPII transports large cargos, cargos with large intracellular domains, and for tethering complexes that must project out of the coat in order to interact with their binding partners. Furthermore, Sec23 binds Sec13/31 at two unique sites in the coat, which suggests that each site may have unique roles in the mechanisms of COPII vesiculation.
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Stagg SM, Lander GC, Quispe J, Voss NR, Cheng A, Bradlow H, Bradlow S, Carragher B, Potter CS. Corrigendum to “A test-bed for optimizing high-resolution single particle reconstructions” [J. Struct. Biol. 163 (2008) 29–39]. J Struct Biol 2010. [DOI: 10.1016/j.jsb.2010.01.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Lander GC, Stagg SM, Voss NR, Cheng A, Fellmann D, Pulokas J, Yoshioka C, Irving C, Mulder A, Lau PW, Lyumkis D, Potter CS, Carragher B. Appion: an integrated, database-driven pipeline to facilitate EM image processing. J Struct Biol 2009; 166:95-102. [PMID: 19263523 DOI: 10.1016/j.jsb.2009.01.002] [Citation(s) in RCA: 664] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The use of cryoEM and three-dimensional image reconstruction is becoming increasingly common. Our vision for this technique is to provide a straightforward manner in which users can proceed from raw data to a reliable 3D reconstruction through a pipeline that both facilitates management of the processing steps and makes the results at each step more transparent. Tightly integrated with a relational SQL database, Appion is a modular and transparent pipeline that extends existing software applications and procedures. The user manages and controls the software modules via web-based forms, and all results are similarly available using web-based viewers directly linked to the underlying database, enabling even naive users to quickly deduce the quality of their results. The Appion API was designed with the principle that applications should be compatible with a broad range of specimens and that libraries and routines are modular and extensible. Presented here is a description of the design and architecture of the working Appion pipeline prototype and some results of its use.
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Affiliation(s)
- Gabriel C Lander
- National Resource for Automated Molecular Microscopy, The Scripps Research Institute, CB 129, 10550 North Torrey Pines Rd, La Jolla, CA 92037, USA
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Stagg SM, LaPointe P, Razvi A, Gürkan C, Potter CS, Carragher B, Balch WE. Structural basis for cargo regulation of COPII coat assembly. Cell 2008; 134:474-84. [PMID: 18692470 DOI: 10.1016/j.cell.2008.06.024] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Revised: 05/01/2008] [Accepted: 06/09/2008] [Indexed: 11/30/2022]
Abstract
Using cryo-electron microscopy, we have solved the structure of an icosidodecahedral COPII coat involved in cargo export from the endoplasmic reticulum (ER) coassembled from purified cargo adaptor Sec23-24 and Sec13-31 lattice-forming complexes. The coat structure shows a tetrameric assembly of the Sec23-24 adaptor layer that is well positioned beneath the vertices and edges of the Sec13-31 lattice. Fitting the known crystal structures of the COPII proteins into the density map reveals a flexible hinge region stemming from interactions between WD40 beta-propeller domains present in Sec13 and Sec31 at the vertices. The structure shows that the hinge region can direct geometric cage expansion to accommodate a wide range of bulky cargo, including procollagen and chylomicrons, that is sensitive to adaptor function in inherited disease. The COPII coat structure leads us to propose a mechanism by which cargo drives cage assembly and membrane curvature for budding from the ER.
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Affiliation(s)
- Scott M Stagg
- National Resource for Automated Molecular Microscopy, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Stagg SM, Lander GC, Quispe J, Voss NR, Cheng A, Bradlow H, Bradlow S, Carragher B, Potter CS. A test-bed for optimizing high-resolution single particle reconstructions. J Struct Biol 2008; 163:29-39. [PMID: 18534866 DOI: 10.1016/j.jsb.2008.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 03/04/2008] [Accepted: 04/01/2008] [Indexed: 01/08/2023]
Abstract
It is becoming routine for cryoEM single particle reconstructions to result in 3D electron density maps with resolutions of approximately 10A, but maps with resolutions of 5A or better are still celebrated events. The electron microscope has a resolving power to better than 2A, and thus should not be a limiting factor; instead the practical limitations in resolution most likely arise from a combination of specimen preparation methods, data collection parameters, and data analysis procedures. With the aid of a highly automated system for acquiring images, coupled to a relational database to keep track of all processing parameters, we have taken a systematic approach to optimizing parameters affecting the resolution of single particle reconstructions. Using GroEL as a test-bed, we performed a series of 3D reconstructions where we systematically varied the number of particles used in computing the map, the accelerating voltage of the microscope, and the electron dose used to acquire the images. We also investigated methods for excluding unacceptable or "bad" particles from contributing to the final 3D map. Using relatively standard instrumentation (Tecnai F20, 4K x 4K CCD, side entry cold stage) and a completely automated approach, these approaches resulted in a map with a nominal resolution of 5.4A (FSC(0.5)) in which secondary structure is clearly discernable and the handedness of some of the alpha-helices in the GroEL structure can be determined.
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Affiliation(s)
- Scott M Stagg
- The National Resource for Automated Molecular Microscopy, Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Stagg SM, LaPointe P, Balch WE. Structural design of cage and coat scaffolds that direct membrane traffic. Curr Opin Struct Biol 2007; 17:221-8. [PMID: 17395454 DOI: 10.1016/j.sbi.2007.03.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 01/31/2007] [Accepted: 03/16/2007] [Indexed: 11/20/2022]
Abstract
Trafficking within the exocytic and endocytic pathways of eukaryotic cells involves the generation of caged transport carriers that mediate communication between compartments through vesicle budding and fusion. Structural studies of vesicle cage structures using X-ray crystallography and cryo-electron microscopy approaches reveal new insight into cargo-dependent coat assembly mechanisms. Clathrin and coat protein complex II (COPII) use conserved primary element alpha-solenoid and WD40 structural motifs found in self-assembling cage scaffolds to generate unique geometries that sort cargo and produce vesicles. These studies emphasize molecular and structural principles that reflect the properties of self-assembling nanomachines to regulate cargo capacity in trafficking pathways.
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Affiliation(s)
- Scott M Stagg
- Department of Cell, The Scripps Research Institute, La Jolla, CA 92037, USA
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Abstract
Communication between compartments of the exocytic and endocytic pathways in eukaryotic cells involves transport carriers - vesicles and tubules - that mediate the vectorial movement of cargo. Recent studies of transport-carrier formation in the early secretory pathway have provided new insights into the mechanisms of cargo selection by coat protein complex-II (COPII) adaptor proteins, the construction of cage-protein scaffolds and fission. These studies are beginning to produce a unifying molecular and structural model of coat function in the formation and fission of vesicles and tubules in endomembrane traffic.
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Affiliation(s)
- Cemal Gürkan
- Department of Electron Microscopy and Molecular Pathology, the Cyprus Institute of Neurology and Genetics, International Airport Avenue #6, Agios Dometios, 1683, Nicosia, Cyprus
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Stagg SM, Lander GC, Pulokas J, Fellmann D, Cheng A, Quispe JD, Mallick SP, Avila RM, Carragher B, Potter CS. Automated cryoEM data acquisition and analysis of 284742 particles of GroEL. J Struct Biol 2006; 155:470-81. [PMID: 16762565 DOI: 10.1016/j.jsb.2006.04.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 04/07/2006] [Accepted: 04/14/2006] [Indexed: 12/01/2022]
Abstract
One of the goals in developing our automated electron microscopy data acquisition system, Leginon, was to improve both the ease of use and the throughput of the process of acquiring low dose images of macromolecular specimens embedded in vitreous ice. In this article, we demonstrate the potential of the Leginon system for high-throughput data acquisition by describing an experiment in which we acquired images of more than 280,000 particles of GroEL in a single 25 h session at the microscope. We also demonstrate the potential for an automated pipeline for molecular microscopy by showing that these particles can be subjected to completely automated procedures to reconstruct a three-dimensional (3D) density map to a resolution better than 8 A. In generating the 3D maps, we used a variety of metadata associated with the data acquisition and processing steps to sort and select the particles. These metadata provide a number of insights into factors that affect the quality of the acquired images and the resulting reconstructions. In particular, we show that the resolution of the reconstructed 3D density maps improves with decreasing ice thickness. These data provide a basis for assessing the capabilities of high-throughput macromolecular microscopy.
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Affiliation(s)
- Scott M Stagg
- The National Resource for Automated Molecular Microscopy, Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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