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Cooney I, Schubert HL, Cedeno K, Lin HJL, Price JC, Hill CP, Shen PS. Visualization of the Cdc48 AAA+ ATPase protein unfolding pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.13.540638. [PMID: 38654823 PMCID: PMC11037871 DOI: 10.1101/2023.05.13.540638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The Cdc48 AAA+ ATPase is an abundant and essential enzyme that unfolds substrates in multiple protein quality control pathways. The enzyme includes two conserved AAA+ ATPase cassettes, D1 and D2, that assemble as hexameric rings with D1 stacked above D2. Here, we report an ensemble of structures of Cdc48 affinity purified from lysate in complex with the adaptor Shp1 in the act of unfolding substrate. Our analysis reveals a continuum of structural snapshots that spans the entire translocation cycle. These data reveal new elements of Shp1-Cdc48 binding and support a "hand-over-hand" mechanism in which the sequential movement of individual subunits is closely coordinated. D1 hydrolyzes ATP and disengages from substrate prior to D2, while D2 rebinds ATP and re-engages with substrate prior to D1, thereby explaining the dominant role played by D2 in substrate translocation/unfolding.
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Affiliation(s)
- Ian Cooney
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Heidi L. Schubert
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Karina Cedeno
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Hsien-Jung L. Lin
- Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, UT, 84602, USA
| | - John C Price
- Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, UT, 84602, USA
| | - Christopher P Hill
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
| | - Peter S Shen
- Department of Biochemistry, 15 N. Medical Drive East, University of Utah, Salt Lake City, UT, 84112, USA
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2
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The Machinery of Exosomes: Biogenesis, Release, and Uptake. Int J Mol Sci 2023; 24:ijms24021337. [PMID: 36674857 PMCID: PMC9865891 DOI: 10.3390/ijms24021337] [Citation(s) in RCA: 81] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/31/2022] [Accepted: 01/04/2023] [Indexed: 01/12/2023] Open
Abstract
Exosomes are a subtype of membrane-contained vesicles 40-200 nm in diameter that are secreted by cells into their surroundings. By transporting proteins, lipids, mRNA, miRNA, lncRNA, and DNA, exosomes are able to perform such vital functions as maintaining cellular homeostasis, removing cellular debris, and facilitating intercellular and interorgan communication. Exosomes travel in all body fluids and deliver their molecular messages in autocrine, paracrine as well as endocrine manners. In recent years, there has been an increased interest in studying exosomes as diagnostic markers and therapeutic targets, since in many disease conditions this machinery becomes dysregulated or hijacked by pathological processes. Additionally, delivery of exosomes and exosomal miRNA has already been shown to improve systemic metabolism and inhibit progression of cancer development in mice. However, the subcellular machinery of exosomes, including their biogenesis, release and uptake, remains largely unknown. This review will bring molecular details of these processes up to date with the goal of expanding the knowledge basis for designing impactful exosome experiments in the future.
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3
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Abstract
The p97 AAA+ATPase is an essential and abundant regulator of protein homeostasis that plays a central role in unfolding ubiquitylated substrates. Here we report two cryo-EM structures of human p97 in complex with its p47 adaptor. One of the conformations is six-fold symmetric, corresponds to previously reported structures of p97, and lacks bound substrate. The other structure adopts a helical conformation, displays substrate running in an extended conformation through the pore of the p97 hexamer, and resembles structures reported for other AAA unfoldases. These findings support the model that p97 utilizes a "hand-over-hand" mechanism in which two residues of the substrate are translocated for hydrolysis of two ATPs, one in each of the two p97 AAA ATPase rings. Proteomics analysis supports the model that one p97 complex can bind multiple substrate adaptors or binding partners, and can process substrates with multiple types of ubiquitin modification.
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4
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Wang L, Toutkoushian H, Belyy V, Kokontis CY, Walter P. Conserved structural elements specialize ATAD1 as a membrane protein extraction machine. eLife 2022; 11:e73941. [PMID: 35550246 PMCID: PMC9273213 DOI: 10.7554/elife.73941] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
The mitochondrial AAA (ATPase Associated with diverse cellular Activities) protein ATAD1 (in humans; Msp1 in yeast) removes mislocalized membrane proteins, as well as stuck import substrates from the mitochondrial outer membrane, facilitating their re-insertion into their cognate organelles and maintaining mitochondria's protein import capacity. In doing so, it helps to maintain proteostasis in mitochondria. How ATAD1 tackles the energetic challenge to extract hydrophobic membrane proteins from the lipid bilayer and what structural features adapt ATAD1 for its particular function has remained a mystery. Previously, we determined the structure of Msp1 in complex with a peptide substrate (Wang et al., 2020). The structure showed that Msp1's mechanism follows the general principle established for AAA proteins while adopting several structural features that specialize it for its function. Among these features in Msp1 was the utilization of multiple aromatic amino acids to firmly grip the substrate in the central pore. However, it was not clear whether the aromatic nature of these amino acids were required, or if they could be functionally replaced by aliphatic amino acids. In this work, we determined the cryo-EM structures of the human ATAD1 in complex with a peptide substrate at near atomic resolution. The structures show that phylogenetically conserved structural elements adapt ATAD1 for its function while generally adopting a conserved mechanism shared by many AAA proteins. We developed a microscopy-based assay reporting on protein mislocalization, with which we directly assessed ATAD1's activity in live cells and showed that both aromatic amino acids in pore-loop 1 are required for ATAD1's function and cannot be substituted by aliphatic amino acids. A short α-helix at the C-terminus strongly facilitates ATAD1's oligomerization, a structural feature that distinguishes ATAD1 from its closely related proteins.
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Affiliation(s)
- Lan Wang
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Hannah Toutkoushian
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Vladislav Belyy
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
| | - Claire Y Kokontis
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California at San FranciscoSan FranciscoUnited States
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5
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An ESCRT/VPS4 envelopment trap to examine the mechanism of alphaherpesvirus assembly and transport in neurons. J Virol 2022; 96:e0217821. [PMID: 35045266 DOI: 10.1128/jvi.02178-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The assembly and egress of alphaherpesviruses, including Herpes simplex virus type 1 (HSV-1) and Pseudorabies virus (PRV), within neurons is poorly understood. A key unresolved question is the structure of the viral particle that moves by anterograde transport along the axon, and two alternative mechanisms have been described. In the "Married" model capsids acquire their envelopes in the cell body, then traffic along axons as enveloped virions within a bounding organelle. In the "Separate" model non-enveloped capsids travel from the cell body into and along the axon, eventually encountering their envelopment organelles at a distal site such as the nerve cell terminal. Here we describe an "envelopment trap" to test these models using the dominant negative terminal ESCRT component VPS4-EQ. GFP-tagged VPS4-EQ was used to arrest HSV-1 or PRV capsid envelopment, inhibit downstream trafficking and GFP-label envelopment intermediates. We found that GFP-VPS4-EQ inhibited trafficking of HSV-1 capsids into and along the neurites and axons of mouse CAD cells and rat embryonic primary cortical neurons, consistent with egress via the married pathway. In contrast, transport of HSV-1 capsids was unaffected in the neurites of human SK-N-SH neuroblastoma cells, consistent with the separate mechanism. Unexpectedly, PRV (generally thought to utilize the married pathway) also appeared to employ the separate mechanism in SK-N-SH cells. We propose that apparent differences in the methods of HSV-1 and PRV egress are more likely a reflection of the host neuron in which transport is studied, rather than true biological differences between the viruses themselves. IMPORTANCE Alphaherpesviruses, including Herpes simplex virus type 1 (HSV-1) and Pseudorabies virus (PRV), are pathogens of the nervous system. They replicate in the nerve cell body then travel great distances along axons to reach nerve termini and spread to adjacent epithelial cells, however key aspects of how these viruses travel along axons remain controversial. Here we test two alternative mechanisms for transport, the married and separate models, by blocking envelope assembly, a critical step in viral egress. When we arrest formation of the viral envelope using a mutated component of the cellular ESCRT apparatus we find that entry of viral particles into axons is blocked in some types of neuron, but not others. This approach allows us to determine whether envelope assembly occurs prior to entry of viruses into axons, or afterwards, and thus to distinguish between the alternative models for viral transport.
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Hurdiss DL, El Kazzi P, Bauer L, Papageorgiou N, Ferron FP, Donselaar T, van Vliet AL, Shamorkina TM, Snijder J, Canard B, Decroly E, Brancale A, Zeev-Ben-Mordehai T, Förster F, van Kuppeveld FJ, Coutard B. Fluoxetine targets an allosteric site in the enterovirus 2C AAA+ ATPase and stabilizes a ring-shaped hexameric complex. SCIENCE ADVANCES 2022; 8:eabj7615. [PMID: 34985963 PMCID: PMC8730599 DOI: 10.1126/sciadv.abj7615] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
Enteroviruses are globally prevalent human pathogens responsible for many diseases. The nonstructural protein 2C is a AAA+ helicase and plays a key role in enterovirus replication. Drug repurposing screens identified 2C-targeting compounds such as fluoxetine and dibucaine, but how they inhibit 2C is unknown. Here, we present a crystal structure of the soluble and monomeric fragment of coxsackievirus B3 2C protein in complex with (S)-fluoxetine (SFX), revealing an allosteric binding site. To study the functional consequences of SFX binding, we engineered an adenosine triphosphatase (ATPase)–competent, hexameric 2C protein. Using this system, we show that SFX, dibucaine, HBB [2-(α-hydroxybenzyl)-benzimidazole], and guanidine hydrochloride inhibit 2C ATPase activity. Moreover, cryo–electron microscopy analysis demonstrated that SFX and dibucaine lock 2C in a defined hexameric state, rationalizing their mode of inhibition. Collectively, these results provide important insights into 2C inhibition and a robust engineering strategy for structural, functional, and drug-screening analysis of 2C proteins.
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Affiliation(s)
- Daniel L. Hurdiss
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, Netherlands
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | | | - Lisa Bauer
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, Netherlands
| | | | | | - Tim Donselaar
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, Netherlands
| | - Arno L.W. van Vliet
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, Netherlands
| | - Tatiana M. Shamorkina
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Bruno Canard
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Etienne Decroly
- Aix Marseille Université, CNRS, AFMB UMR 7257, Marseille, France
| | - Andrea Brancale
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, King Edward VII Avenue, Cardiff CF10 3NB, UK
| | - Tzviya Zeev-Ben-Mordehai
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Friedrich Förster
- Cryo-Electron Microscopy, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Frank J.M. van Kuppeveld
- Virology Section, Infectious Diseases and Immunology Division, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584CL Utrecht, Netherlands
| | - Bruno Coutard
- Unité des Virus Émergents (UVE: Aix-Marseille Univ-IRD 190-Inserm 1207), Marseille, France
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7
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Ye X, Mayne L, Englander SW. A conserved strategy for structure change and energy transduction in Hsp104 and other AAA+ protein motors. J Biol Chem 2021; 297:101066. [PMID: 34384781 PMCID: PMC8449053 DOI: 10.1016/j.jbc.2021.101066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 01/09/2023] Open
Abstract
The superfamily of massively large AAA+ protein molecular machines functions to convert the chemical energy of cytosolic ATP into physicomechanical form and use it to perform an extraordinary number of physical operations on proteins, nucleic acids, and membrane systems. Cryo-EM studies now reveal some aspects of substrate handling at high resolution, but the broader interpretation of AAA+ functional properties is still opaque. This paper integrates recent hydrogen exchange results for the typical AAA+ protein Hsp104 with prior information on several near and distantly related others. The analysis points to a widely conserved functional strategy. Hsp104 cycles through a long-lived loosely-structured energy-input "open" state that releases spent ADP and rebinds cytosolic ATP. ATP-binding energy is transduced by allosteric structure change to poise the protein at a high energy level in a more tightly structured "closed" state. The briefly occupied energy-output closed state binds substrate strongly and is catalytically active. ATP hydrolysis permits energetically downhill structural relaxation, which is coupled to drive energy-requiring substrate processing. Other AAA+ proteins appear to cycle through states that are analogous functionally if not in structural detail. These results revise the current model for AAA+ function, explain the structural basis of single-molecule optical tweezer kinetic phases, identify the separate energetic roles of ATP binding and hydrolysis, and specify a sequence of structural and energetic events that carry AAA+ proteins unidirectionally around a functional cycle to propel their diverse physical tasks.
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Affiliation(s)
- Xiang Ye
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Leland Mayne
- Department of Biochemistry and Biophysics and Johnson Research Foundation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - S Walter Englander
- Department of Biochemistry and Biophysics and Johnson Research Foundation, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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8
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Damre M, Dayananda A, Varikoti RA, Stan G, Dima RI. Factors underlying asymmetric pore dynamics of disaggregase and microtubule-severing AAA+ machines. Biophys J 2021; 120:3437-3454. [PMID: 34181904 PMCID: PMC8391056 DOI: 10.1016/j.bpj.2021.05.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 04/11/2021] [Accepted: 05/19/2021] [Indexed: 11/26/2022] Open
Abstract
Disaggregation and microtubule-severing nanomachines from the AAA+ (ATPases associated with various cellular activities) superfamily assemble into ring-shaped hexamers that enable protein remodeling by coupling large-scale conformational changes with application of mechanical forces within a central pore by loops protruding within the pore. We probed the asymmetric pore motions and intraring interactions that support them by performing extensive molecular dynamics simulations of single-ring severing proteins and the double-ring disaggregase ClpB. Simulations reveal that dynamic stability of hexameric pores of severing proteins and of the nucleotide-binding domain 1 (NBD1) ring of ClpB, which belong to the same clade, involves a network of salt bridges that connect conserved motifs of central pore loops. Clustering analysis of ClpB highlights correlated motions of domains of neighboring protomers supporting strong interprotomer collaboration. Severing proteins have weaker interprotomer coupling and stronger intraprotomer stabilization through salt bridges involving pore loops. Distinct mechanisms are identified in the NBD2 ring of ClpB involving weaker interprotomer coupling through salt bridges formed by noncanonical loops and stronger intraprotomer coupling. Analysis of collective motions of PL1 loops indicates that the largest amplitude motions in the spiral complex of spastin and ClpB involve axial excursions of the loops, whereas for katanin they involve opening and closing of the central pore. All three motors execute primarily axial excursions in the ring complex. These results suggest distinct substrate processing mechanisms of remodeling and translocation by ClpB and spastin compared to katanin, thus providing dynamic support for the differential action of the two severing proteins. Relaxation dynamics of the distance between the PL1 loops and the center of mass of protomers reveals observation-time-dependent dynamics, leading to predicted relaxation times of tens to hundreds of microseconds on millisecond experimental timescales. For ClpB, the predicted relaxation time is in excellent agreement with the extracted time from smFRET experiments.
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Affiliation(s)
- Mangesh Damre
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio
| | - Ashan Dayananda
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio
| | | | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio.
| | - Ruxandra I Dima
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio.
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9
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Baldwin PR, Lyumkis D. Tools for visualizing and analyzing Fourier space sampling in Cryo-EM. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 160:53-65. [PMID: 32645314 PMCID: PMC7785567 DOI: 10.1016/j.pbiomolbio.2020.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 12/15/2022]
Abstract
A complete understanding of how an orientation distribution contributes to a cryo-EM reconstruction remains lacking. It is necessary to begin critically assessing the set of views to gain an understanding of its effect on experimental reconstructions. Toward that end, we recently suggested that the type of orientation distribution may alter resolution measures in a systematic manner. We introduced the sampling compensation factor (SCF), which incorporates how the collection geometry might change the spectral signal-to-noise ratio (SSNR), irrespective of the other experimental aspects. We show here that knowledge of the sampling restricted to spherical surfaces of sufficiently large radii in Fourier space is equivalent to knowledge of the set of projection views. Moreover, the SCF geometrical factor may be calculated from one such surface. To aid cryo-EM practitioners, we developed a graphical user interface (GUI) tool that evaluates experimental orientation distributions. The GUI returns plots of projection directions, sampling constrained to the surface of a sphere, the SCF value, the fraction of the empty region of Fourier space, and a histogram of the sampling values over the points on a sphere. Finally, a fixed tilt angle may be incorporated to determine how tilting the grid during collection may improve the distribution of views and Fourier space sampling. We advocate this simple conception of sampling and the use of such tools as a complement to the distribution of views to capture the different aspects of the effect of projection directions on cryo-EM reconstructions.
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Affiliation(s)
- Philip R Baldwin
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Dmitry Lyumkis
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA; Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N Torrey Pines Road, La Jolla, CA, 92037, USA.
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10
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Seu KG, Trump LR, Emberesh S, Lorsbach RB, Johnson C, Meznarich J, Underhill HR, Chou ST, Sakthivel H, Nassar NN, Seu KJ, Blanc L, Zhang W, Lutzko CM, Kalfa TA. VPS4A Mutations in Humans Cause Syndromic Congenital Dyserythropoietic Anemia due to Cytokinesis and Trafficking Defects. Am J Hum Genet 2020; 107:1149-1156. [PMID: 33186543 DOI: 10.1016/j.ajhg.2020.10.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/26/2020] [Indexed: 11/30/2022] Open
Abstract
The Congenital Dyserythropoietic Anemia (CDA) Registry was established with the goal to facilitate investigations of natural history, biology, and molecular pathogenetic mechanisms of CDA. Three unrelated individuals enrolled in the registry had a syndrome characterized by CDA and severe neurodevelopmental delay. They were found to have missense mutations in VPS4A, a gene coding for an ATPase that regulates the ESCRT-III machinery in a variety of cellular processes including cell division, endosomal vesicle trafficking, and viral budding. Bone marrow studies showed binucleated erythroblasts and erythroblasts with cytoplasmic bridges indicating abnormal cytokinesis and abscission. Circulating red blood cells were found to retain transferrin receptor (CD71) in their membrane, demonstrating that VPS4A is critical for normal reticulocyte maturation. Using proband-derived induced pluripotent stem cells (iPSCs), we have successfully modeled the hematologic aspects of this syndrome in vitro, recapitulating their dyserythropoietic phenotype. Our findings demonstrate that VPS4A mutations cause cytokinesis and trafficking defects leading to a human disease with detrimental effects to erythropoiesis and neurodevelopment.
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Affiliation(s)
- Katie G Seu
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
| | - Lisa R Trump
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Sana Emberesh
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Robert B Lorsbach
- Division of Pathology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Clarissa Johnson
- Pediatric Hematology-Oncology Cook Children's Medical Center, Fort Worth, TX 76104, USA
| | - Jessica Meznarich
- Division of Hematology-Oncology, Department of Pediatrics, University of Utah, Salt Lake City, UT 84132, USA; Primary Children's Hospital, Intermountain Healthcare, Salt Lake City, UT 84113, USA
| | - Hunter R Underhill
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, UT 84108, USA; Department of Radiology, University of Utah, Salt Lake City, UT 84108, USA
| | - Stella T Chou
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Haripriya Sakthivel
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Nicolas N Nassar
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Kalani J Seu
- Department of Chemistry, Earlham College, Richmond, IN 47374, USA
| | - Lionel Blanc
- Laboratory of Developmental Erythropoiesis, Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, Institute of Molecular Medicine, The Feinstein Institutes for Medical Research, Manhasset, NY 11030, USA; Les Nelkin Memorial Pediatric Oncology Laboratory, Institute of Molecular Medicine, The Feinstein Institutes for Medical Research, Manhasset, NY 11030, USA; Department of Molecular Medicine and Pediatrics, Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549, USA
| | - Wenying Zhang
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Laboratory of Genetics and Genomics, Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Carolyn M Lutzko
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA; Hoxworth Blood Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Theodosia A Kalfa
- Division of Hematology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
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11
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Neggers JE, Paolella BR, Asfaw A, Rothberg MV, Skipper TA, Yang A, Kalekar RL, Krill-Burger JM, Dharia NV, Kugener G, Kalfon J, Yuan C, Dumont N, Gonzalez A, Abdusamad M, Li YY, Spurr LF, Wu WW, Durbin AD, Wolpin BM, Piccioni F, Root DE, Boehm JS, Cherniack AD, Tsherniak A, Hong AL, Hahn WC, Stegmaier K, Golub TR, Vazquez F, Aguirre AJ. Synthetic Lethal Interaction between the ESCRT Paralog Enzymes VPS4A and VPS4B in Cancers Harboring Loss of Chromosome 18q or 16q. Cell Rep 2020; 33:108493. [PMID: 33326793 PMCID: PMC8374858 DOI: 10.1016/j.celrep.2020.108493] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 09/04/2020] [Accepted: 11/17/2020] [Indexed: 12/26/2022] Open
Abstract
Few therapies target the loss of tumor suppressor genes in cancer. We examine CRISPR-SpCas9 and RNA-interference loss-of-function screens to identify new therapeutic targets associated with genomic loss of tumor suppressor genes. The endosomal sorting complexes required for transport (ESCRT) ATPases VPS4A and VPS4B score as strong synthetic lethal dependencies. VPS4A is essential in cancers harboring loss of VPS4B adjacent to SMAD4 on chromosome 18q and VPS4B is required in tumors with co-deletion of VPS4A and CDH1 (E-cadherin) on chromosome 16q. We demonstrate that more than 30% of cancers selectively require VPS4A or VPS4B. VPS4A suppression in VPS4B-deficient cells selectively leads to ESCRT-III filament accumulation, cytokinesis defects, nuclear deformation, G2/M arrest, apoptosis, and potent tumor regression. CRISPR-SpCas9 screening and integrative genomic analysis reveal other ESCRT members, regulators of abscission, and interferon signaling as modifiers of VPS4A dependency. We describe a compendium of synthetic lethal vulnerabilities and nominate VPS4A and VPS4B as high-priority therapeutic targets for cancers with 18q or 16q loss. Neggers, Paolella, and colleagues identify the ATPases VPS4A and VPS4B as selective vulnerabilities and potential therapeutic targets in cancers harboring loss of chromosome 18q or 16q. In VPS4B-deficient cancers, VPS4A suppression leads to ESCRT-III dysfunction, nuclear deformation, and abscission defects. Moreover, ESCRT proteins and interferons can modulate dependency on VPS4A.
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Affiliation(s)
- Jasper E Neggers
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Brenton R Paolella
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Adhana Asfaw
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Michael V Rothberg
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Thomas A Skipper
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Annan Yang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Radha L Kalekar
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - John M Krill-Burger
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Neekesh V Dharia
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA; Cancer and Blood Disorders Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Guillaume Kugener
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Jérémie Kalfon
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Chen Yuan
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Nancy Dumont
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alfredo Gonzalez
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Mai Abdusamad
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Yvonne Y Li
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Liam F Spurr
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Westley W Wu
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Adam D Durbin
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA; Cancer and Blood Disorders Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Brian M Wolpin
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Federica Piccioni
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - David E Root
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Jesse S Boehm
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Andrew D Cherniack
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Aviad Tsherniak
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Andrew L Hong
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA; Cancer and Blood Disorders Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - William C Hahn
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Kimberly Stegmaier
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA; Cancer and Blood Disorders Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Todd R Golub
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Francisca Vazquez
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA.
| | - Andrew J Aguirre
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA.
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12
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Horváth P, Müller-Reichert T. A Structural View on ESCRT-Mediated Abscission. Front Cell Dev Biol 2020; 8:586880. [PMID: 33240884 PMCID: PMC7680848 DOI: 10.3389/fcell.2020.586880] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/16/2020] [Indexed: 11/25/2022] Open
Abstract
The endosomal sorting complex required for transport (ESCRT) mediates cellular processes that are related to membrane remodeling, such as multivesicular body (MVB) formation, viral budding and cytokinesis. Abscission is the final stage of cytokinesis that results in the physical separation of the newly formed two daughter cells. Although abscission has been investigated for decades, there are still fundamental open questions related to the spatio-temporal organization of the molecular machinery involved in this process. Reviewing knowledge obtained from in vitro as well as in vivo experiments, we give a brief overview on the role of ESCRT components in abscission mainly focussing on mammalian cells.
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Affiliation(s)
- Péter Horváth
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Thomas Müller-Reichert
- Experimental Center, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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13
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Huber ST, Mostafavi S, Mortensen SA, Sachse C. Structure and assembly of ESCRT-III helical Vps24 filaments. SCIENCE ADVANCES 2020; 6:eaba4897. [PMID: 32875105 PMCID: PMC7438092 DOI: 10.1126/sciadv.aba4897] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 07/08/2020] [Indexed: 06/11/2023]
Abstract
ESCRT-III proteins mediate a range of cellular membrane remodeling activities such as multivesicular body biogenesis, cytokinesis, and viral release. Critical to these processes is the assembly of ESCRT-III subunits into polymeric structures. In this study, we determined the cryo-EM structure of a helical assembly of Saccharomyces cerevisiae Vps24 at 3.2-Å resolution and found that Vps24 adopts an elongated open conformation. Vps24 forms a domain-swapped dimer extended into protofilaments that associate into a double-stranded apolar filament. We demonstrate that, upon binding negatively charged lipids, Vps24 homopolymer filaments undergo partial disassembly into shorter filament fragments and oligomers. Upon the addition of Vps24, Vps2, and Snf7, liposomes are deformed into neck and tubular structures by an ESCRT-III heteropolymer coat. The filamentous Vps24 homopolymer assembly structure and interaction studies reveal how Vps24 could introduce unique geometric properties to mixed-type ESCRT-III heteropolymers and contribute to the process of membrane scission events.
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Affiliation(s)
- Stefan T. Huber
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Siavash Mostafavi
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425 Jülich, Germany
- JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Simon A. Mortensen
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425 Jülich, Germany
- JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425 Jülich, Germany
- European Molecular Biology Laboratory (EMBL) Hamburg c/o DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Carsten Sachse
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons (ER-C-3/Structural Biology), Forschungszentrum Jülich, 52425 Jülich, Germany
- JuStruct: Jülich Center for Structural Biology, Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Chemistry, Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany
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14
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Ahmed I, Akram Z, Sahar MSU, Iqbal HMN, Landsberg MJ, Munn AL. WITHDRAWN: Structural studies of vitrified biological proteins and macromolecules - A review on the microimaging aspects of cryo-electron microscopy. Int J Biol Macromol 2020:S0141-8130(20)33915-5. [PMID: 32710963 DOI: 10.1016/j.ijbiomac.2020.07.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/03/2020] [Accepted: 07/15/2020] [Indexed: 02/08/2023]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Ishtiaq Ahmed
- School of Medical Science, Menzies Health Institute Queensland, Griffith University, Gold Coast campus, Parklands Drive, Southport, QLD 4222, Australia.
| | - Zain Akram
- School of Medical Science, Menzies Health Institute Queensland, Griffith University, Gold Coast campus, Parklands Drive, Southport, QLD 4222, Australia
| | - M Sana Ullah Sahar
- School of Engineering, Griffith University, Gold Coast campus, Parklands Drive, Southport, QLD 4222, Australia
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, CP 64849, Monterrey, N.L., Mexico.
| | - Michael J Landsberg
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Alan L Munn
- School of Medical Science, Menzies Health Institute Queensland, Griffith University, Gold Coast campus, Parklands Drive, Southport, QLD 4222, Australia
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15
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Guo P. High resolution structure of hexameric herpesvirus DNA-packaging motor elucidates revolving mechanism and ends 20-year fervent debate. Protein Cell 2020; 11:311-315. [PMID: 32314326 PMCID: PMC7196596 DOI: 10.1007/s13238-020-00714-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Peixuan Guo
- College of Pharmacy, College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, and Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.
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16
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Translation of the long-term fundamental studies on viral DNA packaging motors into nanotechnology and nanomedicine. SCIENCE CHINA-LIFE SCIENCES 2020; 63:1103-1129. [DOI: 10.1007/s11427-020-1752-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/04/2020] [Indexed: 02/07/2023]
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17
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Cianfrocco MA, Kellogg EH. What Could Go Wrong? A Practical Guide to Single-Particle Cryo-EM: From Biochemistry to Atomic Models. J Chem Inf Model 2020; 60:2458-2469. [PMID: 32078321 DOI: 10.1021/acs.jcim.9b01178] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cryo-electron microscopy (cryo-EM) has enjoyed explosive recent growth due to revolutionary advances in hardware and software, resulting in a steady stream of long-awaited, high-resolution structures with unprecedented atomic detail. With this comes an increased number of microscopes, cryo-EM facilities, and scientists eager to leverage the ability to determine protein structures without crystallization. However, numerous pitfalls and considerations beset the path toward high-resolution structures and are not necessarily obvious from literature surveys. Here, we detail the most common misconceptions when initiating a cryo-EM project and common technical hurdles, as well as their solutions, and we conclude with a vision for the future of this exciting field.
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Affiliation(s)
- Michael A Cianfrocco
- Life Sciences Institute and Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Elizabeth H Kellogg
- Department of Molecular Biology and Genetics,Cornell University, Ithaca, New York 14850, United States
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18
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Fei X, Bell TA, Jenni S, Stinson BM, Baker TA, Harrison SC, Sauer RT. Structures of the ATP-fueled ClpXP proteolytic machine bound to protein substrate. eLife 2020; 9:52774. [PMID: 32108573 PMCID: PMC7112951 DOI: 10.7554/elife.52774] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/27/2020] [Indexed: 01/11/2023] Open
Abstract
ClpXP is an ATP-dependent protease in which the ClpX AAA+ motor binds, unfolds, and translocates specific protein substrates into the degradation chamber of ClpP. We present cryo-EM studies of the E. coli enzyme that show how asymmetric hexameric rings of ClpX bind symmetric heptameric rings of ClpP and interact with protein substrates. Subunits in the ClpX hexamer assume a spiral conformation and interact with two-residue segments of substrate in the axial channel, as observed for other AAA+ proteases and protein-remodeling machines. Strictly sequential models of ATP hydrolysis and a power stroke that moves two residues of the substrate per translocation step have been inferred from these structural features for other AAA+ unfoldases, but biochemical and single-molecule biophysical studies indicate that ClpXP operates by a probabilistic mechanism in which five to eight residues are translocated for each ATP hydrolyzed. We propose structure-based models that could account for the functional results.
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Affiliation(s)
- Xue Fei
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Tristan A Bell
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Benjamin M Stinson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Howard Hughes Medical Institute, Chevy Chase, United States
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Chevy Chase, United States
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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19
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Wang L, Myasnikov A, Pan X, Walter P. Structure of the AAA protein Msp1 reveals mechanism of mislocalized membrane protein extraction. eLife 2020; 9:e54031. [PMID: 31999255 PMCID: PMC7018516 DOI: 10.7554/elife.54031] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 01/29/2020] [Indexed: 01/03/2023] Open
Abstract
The AAA protein Msp1 extracts mislocalized tail-anchored membrane proteins and targets them for degradation, thus maintaining proper cell organization. How Msp1 selects its substrates and firmly engages them during the energetically unfavorable extraction process remains a mystery. To address this question, we solved cryo-EM structures of Msp1-substrate complexes at near-atomic resolution. Akin to other AAA proteins, Msp1 forms hexameric spirals that translocate substrates through a central pore. A singular hydrophobic substrate recruitment site is exposed at the spiral's seam, which we propose positions the substrate for entry into the pore. There, a tight web of aromatic amino acids grips the substrate in a sequence-promiscuous, hydrophobic milieu. Elements at the intersubunit interfaces coordinate ATP hydrolysis with the subunits' positions in the spiral. We present a comprehensive model of Msp1's mechanism, which follows general architectural principles established for other AAA proteins yet specializes Msp1 for its unique role in membrane protein extraction.
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Affiliation(s)
- Lan Wang
- Howard Hughes Medical InstituteChevy Chase, MarylandUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Alexander Myasnikov
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Centre for Integrative Biology, Department of Integrated Structural Biology, IGBMC, CNRS, Inserm, Université de StrasbourgIllkirchFrance
| | - Xingjie Pan
- UCSF/UCB Graduate Program in Bioengineering, University of California, San FranciscoSan FranciscoUnited States
| | - Peter Walter
- Howard Hughes Medical InstituteChevy Chase, MarylandUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
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20
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Jessop M, Arragain B, Miras R, Fraudeau A, Huard K, Bacia-Verloop M, Catty P, Felix J, Malet H, Gutsche I. Structural insights into ATP hydrolysis by the MoxR ATPase RavA and the LdcI-RavA cage-like complex. Commun Biol 2020; 3:46. [PMID: 31992852 PMCID: PMC6987120 DOI: 10.1038/s42003-020-0772-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 01/11/2020] [Indexed: 01/13/2023] Open
Abstract
The hexameric MoxR AAA+ ATPase RavA and the decameric lysine decarboxylase LdcI form a 3.3 MDa cage, proposed to assist assembly of specific respiratory complexes in E. coli. Here, we show that inside the LdcI-RavA cage, RavA hexamers adopt an asymmetric spiral conformation in which the nucleotide-free seam is constrained to two opposite orientations. Cryo-EM reconstructions of free RavA reveal two co-existing structural states: an asymmetric spiral, and a flat C2-symmetric closed ring characterised by two nucleotide-free seams. The closed ring RavA state bears close structural similarity to the pseudo two-fold symmetric crystal structure of the AAA+ unfoldase ClpX, suggesting a common ATPase mechanism. Based on these structures, and in light of the current knowledge regarding AAA+ ATPases, we propose different scenarios for the ATP hydrolysis cycle of free RavA and the LdcI-RavA cage-like complex, and extend the comparison to other AAA+ ATPases of clade 7.
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Affiliation(s)
- Matthew Jessop
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Benoit Arragain
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Roger Miras
- Laboratoire de Chimie et Biologie des Métaux, Univ. Grenoble Alpes, CEA, CNRS, DRF, IRIG, UMR 5249, 17 rue des Martyrs, F-38054, Grenoble, France
| | - Angélique Fraudeau
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Karine Huard
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Maria Bacia-Verloop
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Patrice Catty
- Laboratoire de Chimie et Biologie des Métaux, Univ. Grenoble Alpes, CEA, CNRS, DRF, IRIG, UMR 5249, 17 rue des Martyrs, F-38054, Grenoble, France
| | - Jan Felix
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France.
| | - Hélène Malet
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France.
| | - Irina Gutsche
- Institut de Biologie Structurale, Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France.
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21
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Kater L, Wagener N, Berninghausen O, Becker T, Neupert W, Beckmann R. Structure of the Bcs1 AAA-ATPase suggests an airlock-like translocation mechanism for folded proteins. Nat Struct Mol Biol 2020; 27:142-149. [DOI: 10.1038/s41594-019-0364-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/13/2019] [Indexed: 11/09/2022]
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22
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Zehr EA, Szyk A, Szczesna E, Roll-Mecak A. Katanin Grips the β-Tubulin Tail through an Electropositive Double Spiral to Sever Microtubules. Dev Cell 2020; 52:118-131.e6. [PMID: 31735665 PMCID: PMC7060837 DOI: 10.1016/j.devcel.2019.10.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 09/11/2019] [Accepted: 10/14/2019] [Indexed: 11/16/2022]
Abstract
The AAA ATPase katanin severs microtubules. It is critical in cell division, centriole biogenesis, and neuronal morphogenesis. Its mutation causes microcephaly. The microtubule templates katanin hexamerization and activates its ATPase. The structural basis for these activities and how they lead to severing is unknown. Here, we show that β-tubulin tails are necessary and sufficient for severing. Cryoelectron microscopy (cryo-EM) structures reveal the essential tubulin tail glutamates gripped by a double spiral of electropositive loops lining the katanin central pore. Each spiral couples allosterically to the ATPase and binds alternating, successive substrate residues, with consecutive residues coordinated by adjacent protomers. This tightly couples tail binding, hexamerization, and ATPase activation. Hexamer structures in different states suggest an ATPase-driven, ratchet-like translocation of the tubulin tail through the pore. A disordered region outside the AAA core anchors katanin to the microtubule while the AAA motor exerts the forces that extract tubulin dimers and sever the microtubule.
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Affiliation(s)
- Elena A Zehr
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20982, USA
| | - Agnieszka Szyk
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20982, USA
| | - Ewa Szczesna
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20982, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20982, USA; Biochemistry and Biophysics Center, National Heart Lung and Blood Institute, Bethesda, MD 20892, USA.
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23
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Han H, Schubert HL, McCullough J, Monroe N, Purdy MD, Yeager M, Sundquist WI, Hill CP. Structure of spastin bound to a glutamate-rich peptide implies a hand-over-hand mechanism of substrate translocation. J Biol Chem 2019; 295:435-443. [PMID: 31767681 DOI: 10.1074/jbc.ac119.009890] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 11/11/2019] [Indexed: 11/06/2022] Open
Abstract
Many members of the AAA+ ATPase family function as hexamers that unfold their protein substrates. These AAA unfoldases include spastin, which plays a critical role in the architecture of eukaryotic cells by driving the remodeling and severing of microtubules, which are cytoskeletal polymers of tubulin subunits. Here, we demonstrate that a human spastin binds weakly to unmodified peptides from the C-terminal segment of human tubulin α1A/B. A peptide comprising alternating glutamate and tyrosine residues binds more tightly, which is consistent with the known importance of glutamylation for spastin microtubule severing activity. A cryo-EM structure of the spastin-peptide complex at 4.2 Å resolution revealed an asymmetric hexamer in which five spastin subunits adopt a helical, spiral staircase configuration that binds the peptide within the central pore, whereas the sixth subunit of the hexamer is displaced from the peptide/substrate, as if transitioning from one end of the helix to the other. This configuration differs from a recently published structure of spastin from Drosophila melanogaster, which forms a six-subunit spiral without a transitioning subunit. Our structure resembles other recently reported AAA unfoldases, including the meiotic clade relative Vps4, and supports a model in which spastin utilizes a hand-over-hand mechanism of tubulin translocation and microtubule remodeling.
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Affiliation(s)
- Han Han
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
| | - Heidi L Schubert
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
| | - John McCullough
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
| | - Nicole Monroe
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908; Department of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908; Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, Virginia 22908; Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia 22908
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112.
| | - Christopher P Hill
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112.
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24
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Shorter J, Southworth DR. Spiraling in Control: Structures and Mechanisms of the Hsp104 Disaggregase. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a034033. [PMID: 30745294 DOI: 10.1101/cshperspect.a034033] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hsp104 is a hexameric AAA+ ATPase and protein disaggregase found in yeast, which couples ATP hydrolysis to the dissolution of diverse polypeptides trapped in toxic preamyloid oligomers, phase-transitioned gels, disordered aggregates, amyloids, and prions. Hsp104 shows plasticity in disaggregating diverse substrates, but how its hexameric architecture operates as a molecular machine has remained unclear. Here, we highlight structural advances made via cryoelectron microscopy (cryo-EM) that enhance our mechanistic understanding of Hsp104 and other related AAA+ translocases. Hsp104 hexamers are dynamic and adopt open "lock-washer" spiral states and closed ring structures that envelope polypeptide substrate inside the axial channel. ATP hydrolysis-driven conformational changes at the spiral seam ratchet substrate deeper into the channel. Remarkably, this mode of polypeptide translocation is reminiscent of models for how hexameric helicases unwind DNA and RNA duplexes. Thus, Hsp104 likely adapts elements of a deeply rooted, ring-translocase mechanism to the specialized task of protein disaggregation.
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Affiliation(s)
- James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Daniel R Southworth
- Department of Biochemistry and Biophysics; and the Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, California 94158
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25
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Guo P, Driver D, Zhao Z, Zheng Z, Chan C, Cheng X. Controlling the Revolving and Rotating Motion Direction of Asymmetric Hexameric Nanomotor by Arginine Finger and Channel Chirality. ACS NANO 2019; 13:6207-6223. [PMID: 31067030 PMCID: PMC6595433 DOI: 10.1021/acsnano.8b08849] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Nanomotors in nanotechnology are as important as engines in daily life. Many ATPases are nanoscale biomotors classified into three categories based on the motion mechanisms in transporting substrates: linear, rotating, and the recently discovered revolving motion. Most biomotors adopt a multisubunit ring-shaped structure that hydrolyzes ATP to generate force. How these biomotors control the motion direction and regulate the sequential action of their multiple subunits is intriguing. Many ATPases are hexameric with each monomer containing a conserved arginine finger. This review focuses on recent findings on how the arginine finger controls motion direction and coordinates adjacent subunit interactions in both revolving and rotating biomotors. Mechanisms of intersubunit interactions and sequential movements of individual subunits are evidenced by the asymmetrical appearance of one dimer and four monomers in high-resolution structural complexes. The arginine finger is situated at the interface of two subunits and extends into the ATP binding pocket of the downstream subunit. An arginine finger mutation results in deficiency in ATP binding/hydrolysis, substrate binding, and transport, highlighting the importance of the arginine finger in regulating energy transduction and motor function. Additionally, the roles of channel chirality and channel size are discussed as related to controlling one-way trafficking and differentiating the revolving and rotating mechanisms. Finally, the review concludes by discussing the conformational changes and entropy conversion triggered by ATP binding/hydrolysis, offering a view different from the traditional concept of ATP-mediated mechanochemical energy coupling. The elucidation of the motion mechanism and direction control in ATPases could facilitate nanomotor fabrication in nanotechnology.
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Affiliation(s)
- Peixuan Guo
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
- E-mail:
| | - Dana Driver
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
| | - Zhengyi Zhao
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
| | - Zhen Zheng
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
| | - Chun Chan
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
| | - Xiaolin Cheng
- Center
for RNA Nanobiotechnology and Nanomedicine, College of Pharmacy
and College of Medicine, Dorothy M. Davis Heart and Lung Research
Institute, Comprehensive Cancer Center and College of Pharmacy, Biophysics
Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United
States
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26
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Deville C, Franke K, Mogk A, Bukau B, Saibil HR. Two-Step Activation Mechanism of the ClpB Disaggregase for Sequential Substrate Threading by the Main ATPase Motor. Cell Rep 2019; 27:3433-3446.e4. [PMID: 31216466 PMCID: PMC6593972 DOI: 10.1016/j.celrep.2019.05.075] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 04/26/2019] [Accepted: 05/20/2019] [Indexed: 11/20/2022] Open
Abstract
AAA+ proteins form asymmetric hexameric rings that hydrolyze ATP and thread substrate proteins through a central channel via mobile substrate-binding pore loops. Understanding how ATPase and threading activities are regulated and intertwined is key to understanding the AAA+ protein mechanism. We studied the disaggregase ClpB, which contains tandem ATPase domains (AAA1, AAA2) and shifts between low and high ATPase and threading activities. Coiled-coil M-domains repress ClpB activity by encircling the AAA1 ring. Here, we determine the mechanism of ClpB activation by comparing ATPase mechanisms and cryo-EM structures of ClpB wild-type and a constitutively active ClpB M-domain mutant. We show that ClpB activation reduces ATPase cooperativity and induces a sequential mode of ATP hydrolysis in the AAA2 ring, the main ATPase motor. AAA1 and AAA2 rings do not work synchronously but in alternating cycles. This ensures high grip, enabling substrate threading via a processive, rope-climbing mechanism.
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Affiliation(s)
- Célia Deville
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Kamila Franke
- Center for Molecular Biology of University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Bernd Bukau
- Center for Molecular Biology of University of Heidelberg (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Helen R Saibil
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK.
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27
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Ahmed I, Akram Z, Iqbal HMN, Munn AL. The regulation of Endosomal Sorting Complex Required for Transport and accessory proteins in multivesicular body sorting and enveloped viral budding - An overview. Int J Biol Macromol 2019; 127:1-11. [PMID: 30615963 DOI: 10.1016/j.ijbiomac.2019.01.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/03/2019] [Accepted: 01/03/2019] [Indexed: 02/07/2023]
Abstract
ESCRT (Endosomal Sorting Complex Required for Transport) machinery drives different cellular processes such as endosomal sorting, organelle biogenesis, vesicular trafficking, maintenance of plasma membrane integrity, membrane fission during cytokinesis and enveloped virus budding. The normal cycle of assembly and disassembly of some ESCRT complexes at the membrane requires the AAA-ATPase vacuolar protein sorting 4 (Vps4p). A number of ESCRT proteins are hijacked by clinically significant enveloped viruses including Ebola, and Human Immunodeficiency Virus (HIV) to enable enveloped virus budding and Vps4p provides energy for the disassembly/recycling of these ESCRT proteins. Several years ago, the failure of the terminal budding process of HIV following Vps4 protein inhibition was published; although at that time a detailed understanding of the molecular players was missing. However, later it was acknowledged that the ESCRT machinery has a role in enveloped virus budding from cells due to its role in the multivesicular body (MVB) sorting pathway. The MVB sorting pathway facilitates several cellular activities in uninfected cells, such as the down-regulation of signaling through cell surface receptors as well as the process of viral budding from infected host cells. In this review, we focus on summarising the functional organisation of ESCRT proteins at the membrane and the role of ESCRT machinery and Vps4p during MVB sorting and enveloped viral budding.
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Affiliation(s)
- Ishtiaq Ahmed
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia.
| | - Zain Akram
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N. L. CP 64849, Mexico
| | - Alan L Munn
- School of Medical Science, Menzies Health Institute Queensland, Griffith University (Gold Coast campus), Parklands Drive, Southport, QLD 4222, Australia.
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28
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Thaller DJ, Allegretti M, Borah S, Ronchi P, Beck M, Lusk CP. An ESCRT-LEM protein surveillance system is poised to directly monitor the nuclear envelope and nuclear transport system. eLife 2019; 8:e45284. [PMID: 30942170 PMCID: PMC6461442 DOI: 10.7554/elife.45284] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022] Open
Abstract
The integrity of the nuclear membranes coupled to the selective barrier of nuclear pore complexes (NPCs) are essential for the segregation of nucleoplasm and cytoplasm. Mechanical membrane disruption or perturbation to NPC assembly triggers an ESCRT-dependent surveillance system that seals nuclear pores: how these pores are sensed and sealed is ill defined. Using a budding yeast model, we show that the ESCRT Chm7 and the integral inner nuclear membrane (INM) protein Heh1 are spatially segregated by nuclear transport, with Chm7 being actively exported by Xpo1/Crm1. Thus, the exposure of the INM triggers surveillance with Heh1 locally activating Chm7. Sites of Chm7 hyperactivation show fenestrated sheets at the INM and potential membrane delivery at sites of nuclear envelope herniation. Our data suggest that perturbation to the nuclear envelope barrier would lead to local nuclear membrane remodeling to promote membrane sealing. Our findings have implications for disease mechanisms linked to NPC assembly and nuclear envelope integrity.
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Affiliation(s)
- David J Thaller
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
| | - Matteo Allegretti
- Structural and Computational Biology UnitEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - Sapan Borah
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
| | - Paolo Ronchi
- Electron Microscopy Core FacilityEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - Martin Beck
- Structural and Computational Biology UnitEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - C Patrick Lusk
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
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29
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The role of VPS4 in ESCRT-III polymer remodeling. Biochem Soc Trans 2019; 47:441-448. [DOI: 10.1042/bst20180026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/16/2019] [Accepted: 01/21/2019] [Indexed: 01/04/2023]
Abstract
Abstract
The endosomal sorting complex required for transport-III (ESCRT-III) and VPS4 catalyze a variety of membrane-remodeling processes in eukaryotes and archaea. Common to these processes is the dynamic recruitment of ESCRT-III proteins from the cytosol to the inner face of a membrane neck structure, their activation and filament formation inside or at the membrane neck and the subsequent or concomitant recruitment of the AAA-type ATPase VPS4. The dynamic assembly of ESCRT-III filaments and VPS4 on cellular membranes induces constriction of membrane necks with large diameters such as the cytokinetic midbody and necks with small diameters such as those of intraluminal vesicles or enveloped viruses. The two processes seem to use different sets of ESCRT-III filaments. Constriction is then thought to set the stage for membrane fission. Here, we review recent progress in understanding the structural transitions of ESCRT-III proteins required for filament formation, the functional role of VPS4 in dynamic ESCRT-III assembly and its active role in filament constriction. The recent data will be discussed in the context of different mechanistic models for inside-out membrane fission.
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30
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Cryo-EM structure of the essential ribosome assembly AAA-ATPase Rix7. Nat Commun 2019; 10:513. [PMID: 30705282 PMCID: PMC6355894 DOI: 10.1038/s41467-019-08373-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/28/2018] [Indexed: 01/24/2023] Open
Abstract
Rix7 is an essential type II AAA-ATPase required for the formation of the large ribosomal subunit. Rix7 has been proposed to utilize the power of ATP hydrolysis to drive the removal of assembly factors from pre-60S particles, but the mechanism of release is unknown. Rix7's mammalian homolog, NVL2 has been linked to cancer and mental illness disorders, highlighting the need to understand the molecular mechanisms of this essential machine. Here we report the cryo-EM reconstruction of the tandem AAA domains of Rix7 which form an asymmetric stacked homohexameric ring. We trapped Rix7 with a polypeptide in the central channel, revealing Rix7's role as a molecular unfoldase. The structure establishes that type II AAA-ATPases lacking the aromatic-hydrophobic motif within the first AAA domain can engage a substrate throughout the entire central channel. The structure also reveals that Rix7 contains unique post-α7 insertions within both AAA domains important for Rix7 function.
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31
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Structure and mechanism of the ESCRT pathway AAA+ ATPase Vps4. Biochem Soc Trans 2019; 47:37-45. [PMID: 30647138 PMCID: PMC6393862 DOI: 10.1042/bst20180260] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 10/24/2018] [Accepted: 10/29/2018] [Indexed: 01/05/2023]
Abstract
The progression of ESCRT (Endosomal Sorting Complexes Required for Transport) pathways, which mediate numerous cellular membrane fission events, is driven by the enzyme Vps4. Understanding of Vps4 mechanism is, therefore, of fundamental importance in its own right and, moreover, it is highly relevant to the understanding of many related AAA+ ATPases that function in multiple facets of cell biology. Vps4 unfolds its ESCRT-III protein substrates by translocating them through its central hexameric pore, thereby driving membrane fission and recycling of ESCRT-III subunits. This mini-review focuses on recent advances in Vps4 structure and mechanism, including ideas about how Vps4 translocates and unfolds ESCRT-III subunits. Related AAA+ ATPases that share structural features with Vps4 and likely utilize an equivalent mechanism are also discussed.
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32
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Cryo-EM structures of the archaeal PAN-proteasome reveal an around-the-ring ATPase cycle. Proc Natl Acad Sci U S A 2018; 116:534-539. [PMID: 30559193 PMCID: PMC6329974 DOI: 10.1073/pnas.1817752116] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteasomes are ATP-dependent proteases that occur in all three domains of life, and are the principal molecular machines for the regulated degradation of intracellular proteins. The eukaryotic 26S proteasome has been extensively characterized. However, its evolutionary precursor, the archaeal proteasome–ATPase complex, remains poorly understood. The inherent instability of these primordial protein complexes has so far hindered attempts for detailed structure determination. Using cryo-EM single-particle analysis, we were able to determine the structure of an archaeal PAN-proteasome, which is a complex of the proteolytic core and the ATPase PAN (proteasome-activating nucleotidase). The structures reported here not only provide insights into the functional cycle of PAN-proteasomes, they reveal a fundamental mechanism of ATPase operation. Proteasomes occur in all three domains of life, and are the principal molecular machines for the regulated degradation of intracellular proteins. They play key roles in the maintenance of protein homeostasis, and control vital cellular processes. While the eukaryotic 26S proteasome is extensively characterized, its putative evolutionary precursor, the archaeal proteasome, remains poorly understood. The primordial archaeal proteasome consists of a 20S proteolytic core particle (CP), and an AAA-ATPase module. This minimal complex degrades protein unassisted by non-ATPase subunits that are present in a 26S proteasome regulatory particle (RP). Using cryo-EM single-particle analysis, we determined structures of the archaeal CP in complex with the AAA-ATPase PAN (proteasome-activating nucleotidase). Five conformational states were identified, elucidating the functional cycle of PAN, and its interaction with the CP. Coexisting nucleotide states, and correlated intersubunit signaling features, coordinate rotation of the PAN-ATPase staircase, and allosterically regulate N-domain motions and CP gate opening. These findings reveal the structural basis for a sequential around-the-ring ATPase cycle, which is likely conserved in AAA-ATPases.
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33
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Su M. goCTF: Geometrically optimized CTF determination for single-particle cryo-EM. J Struct Biol 2018; 205:22-29. [PMID: 30496818 DOI: 10.1016/j.jsb.2018.11.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/20/2018] [Accepted: 11/26/2018] [Indexed: 10/27/2022]
Abstract
Preferred particle orientation represents a recurring problem in single-particle cryogenic electron microcopy (cryo-EM). A specimen-independent approach through tilting has been attempted to increase particle orientation coverage, thus minimizing anisotropic three-dimensional (3D) reconstruction. However, focus gradient is a critical issue hindering tilt applications from being a general practice in single-particle cryo-EM. The present study describes a newly developed geometrically optimized approach, goCTF, to reliably determine the global focus gradient. A novel strategy of determining contrast transfer function (CTF) parameters from a sector of the signal preserved power spectrum is applied to increase reliability. Subsequently, per-particle based local focus refinement is conducted in an iterative manner to further improve the defocus accuracy. Novel diagnosis methods using a standard deviation defocus plot and goodness of fit heatmap have also been proposed to evaluate CTF fitting quality prior to 3D refinement. In a benchmark study, goCTF processed a published single-particle cryo-EM dataset for influenza hemagglutinin trimer collected at a 40-degree specimen tilt. The resulting 3D reconstruction map was improved from 4.1 Å to 3.7 Å resolution. The goCTF program is built on the open-source code of CTFFIND4, which adopts a consistent user interface for ease of use.
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Affiliation(s)
- Min Su
- University of Michigan Life Sciences Institute, Ann Arbor 48109, USA.
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34
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McCullough J, Frost A, Sundquist WI. Structures, Functions, and Dynamics of ESCRT-III/Vps4 Membrane Remodeling and Fission Complexes. Annu Rev Cell Dev Biol 2018; 34:85-109. [PMID: 30095293 PMCID: PMC6241870 DOI: 10.1146/annurev-cellbio-100616-060600] [Citation(s) in RCA: 162] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The endosomal sorting complexes required for transport (ESCRT) pathway mediates cellular membrane remodeling and fission reactions. The pathway comprises five core complexes: ALIX, ESCRT-I, ESCRT-II, ESCRT-III, and Vps4. These soluble complexes are typically recruited to target membranes by site-specific adaptors that bind one or both of the early-acting ESCRT factors: ALIX and ESCRT-I/ESCRT-II. These factors, in turn, nucleate assembly of ESCRT-III subunits into membrane-bound filaments that recruit the AAA ATPase Vps4. Together, ESCRT-III filaments and Vps4 remodel and sever membranes. Here, we review recent advances in our understanding of the structures, activities, and mechanisms of the ESCRT-III and Vps4 machinery, including the first high-resolution structures of ESCRT-III filaments, the assembled Vps4 enzyme in complex with an ESCRT-III substrate, the discovery that ESCRT-III/Vps4 complexes can promote both inside-out and outside-in membrane fission reactions, and emerging mechanistic models for ESCRT-mediated membrane fission.
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Affiliation(s)
- John McCullough
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA;
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA
- Chan Zuckerberg Biohub, San Francisco, California 94158, USA
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA;
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35
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Nithianantham S, McNally FJ, Al-Bassam J. Structural basis for disassembly of katanin heterododecamers. J Biol Chem 2018; 293:10590-10605. [PMID: 29752405 DOI: 10.1074/jbc.ra117.001215] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 04/20/2018] [Indexed: 11/06/2022] Open
Abstract
The reorganization of microtubules in mitosis, meiosis, and development requires the microtubule-severing activity of katanin. Katanin is a heterodimer composed of an ATPase associated with diverse cellular activities (AAA) subunit and a regulatory subunit. Microtubule severing requires ATP hydrolysis by katanin's conserved AAA ATPase domains. Whereas other AAA ATPases form stable hexamers, we show that katanin forms only a monomer or dimers of heterodimers in solution. Katanin oligomers consistent with hexamers of heterodimers or heterododecamers were only observed for an ATP hydrolysis-deficient mutant in the presence of ATP. X-ray structures of katanin's AAA ATPase in monomeric nucleotide-free and pseudo-oligomeric ADP-bound states revealed conformational changes in the AAA subdomains that explained the structural basis for the instability of the katanin heterododecamer. We propose that the rapid dissociation of katanin AAA oligomers may lead to an autoinhibited state that prevents inappropriate microtubule severing or that cyclical disassembly into heterodimers may critically contribute to the microtubule-severing mechanism.
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Affiliation(s)
- Stanley Nithianantham
- From the Department of Molecular Cellular Biology University of California, Davis, California 95616
| | - Francis J McNally
- From the Department of Molecular Cellular Biology University of California, Davis, California 95616
| | - Jawdat Al-Bassam
- From the Department of Molecular Cellular Biology University of California, Davis, California 95616
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36
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Caspi Y, Dekker C. Dividing the Archaeal Way: The Ancient Cdv Cell-Division Machinery. Front Microbiol 2018; 9:174. [PMID: 29551994 PMCID: PMC5840170 DOI: 10.3389/fmicb.2018.00174] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/25/2018] [Indexed: 01/06/2023] Open
Abstract
Cell division in most prokaryotes is mediated by the well-studied fts genes, with FtsZ as the principal player. In many archaeal species, however, division is orchestrated differently. The Crenarchaeota phylum of archaea features the action of the three proteins, CdvABC. This Cdv system is a unique and less-well-studied division mechanism that merits closer inspection. In vivo, the three Cdv proteins form a composite band that contracts concomitantly with the septum formation. Of the three Cdv proteins, CdvA is the first to be recruited to the division site, while CdvB and CdvC are thought to participate in the active part of the Cdv division machinery. Interestingly, CdvB shares homology with a family of proteins from the eukaryotic ESCRT-III complex, and CdvC is a homolog of the eukaryotic Vps4 complex. These two eukaryotic complexes are key factors in the endosomal sorting complex required for transport (ESCRT) pathway, which is responsible for various budding processes in eukaryotic cells and which participates in the final stages of division in Metazoa. There, ESCRT-III forms a contractile machinery that actively cuts the membrane, whereas Vps4, which is an ATPase, is necessary for the turnover of the ESCRT membrane-abscission polymers. In contrast to CdvB and CdvC, CdvA is unique to the archaeal Crenarchaeota and Thaumarchaeota phyla. The Crenarchaeota division mechanism has often been suggested to represent a simplified version of the ESCRT division machinery thus providing a model system to study the evolution and mechanism of cell division in higher organisms. However, there are still many open questions regarding this parallelism and the division mechanism of Crenarchaeota. Here, we review the existing data on the role of the Cdv proteins in the division process of Crenarchaeota as well as concisely review the ESCRT system in eukaryotes. We survey the similarities and differences between the division and abscission mechanisms in the two cases. We suggest that the Cdv system functions differently in archaea than ESCRT does in eukaryotes, and that, unlike the eukaryotic case, the Cdv system's main function may be related to surplus membrane invagination and cell-wall synthesis.
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Affiliation(s)
- Yaron Caspi
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands
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37
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38
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39
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Han H, Monroe N, Sundquist WI, Shen PS, Hill CP. The AAA ATPase Vps4 binds ESCRT-III substrates through a repeating array of dipeptide-binding pockets. eLife 2017; 6:31324. [PMID: 29165244 PMCID: PMC5716660 DOI: 10.7554/elife.31324] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 11/21/2017] [Indexed: 01/02/2023] Open
Abstract
The hexameric AAA ATPase Vps4 drives membrane fission by remodeling and disassembling ESCRT-III filaments. Building upon our earlier 4.3 Å resolution cryo-EM structure (Monroe et al., 2017), we now report a 3.2 Å structure of Vps4 bound to an ESCRT-III peptide substrate. The new structure reveals that the peptide approximates a β-strand conformation whose helical symmetry matches that of the five Vps4 subunits it contacts directly. Adjacent Vps4 subunits make equivalent interactions with successive substrate dipeptides through two distinct classes of side chain binding pockets formed primarily by Vps4 pore loop 1. These pockets accommodate a wide range of residues, while main chain hydrogen bonds may help dictate substrate-binding orientation. The structure supports a ‘conveyor belt’ model of translocation in which ATP binding allows a Vps4 subunit to join the growing end of the helix and engage the substrate, while hydrolysis and release promotes helix disassembly and substrate release at the lagging end.
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Affiliation(s)
- Han Han
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Nicole Monroe
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Peter S Shen
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Christopher P Hill
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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40
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Adell MAY, Migliano SM, Upadhyayula S, Bykov YS, Sprenger S, Pakdel M, Vogel GF, Jih G, Skillern W, Behrouzi R, Babst M, Schmidt O, Hess MW, Briggs JA, Kirchhausen T, Teis D. Recruitment dynamics of ESCRT-III and Vps4 to endosomes and implications for reverse membrane budding. eLife 2017; 6:31652. [PMID: 29019322 PMCID: PMC5665648 DOI: 10.7554/elife.31652] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 09/25/2017] [Indexed: 12/18/2022] Open
Abstract
The ESCRT machinery mediates reverse membrane scission. By quantitative fluorescence lattice light-sheet microscopy, we have shown that ESCRT-III subunits polymerize rapidly on yeast endosomes, together with the recruitment of at least two Vps4 hexamers. During their 3–45 s lifetimes, the ESCRT-III assemblies accumulated 75–200 Snf7 and 15–50 Vps24 molecules. Productive budding events required at least two additional Vps4 hexamers. Membrane budding was associated with continuous, stochastic exchange of Vps4 and ESCRT-III components, rather than steady growth of fixed assemblies, and depended on Vps4 ATPase activity. An all-or-none step led to final release of ESCRT-III and Vps4. Tomographic electron microscopy demonstrated that acute disruption of Vps4 recruitment stalled membrane budding. We propose a model in which multiple Vps4 hexamers (four or more) draw together several ESCRT-III filaments. This process induces cargo crowding and inward membrane buckling, followed by constriction of the nascent bud neck and ultimately ILV generation by vesicle fission.
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Affiliation(s)
- Manuel Alonso Y Adell
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Simona M Migliano
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Srigokul Upadhyayula
- Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Yury S Bykov
- Structural and Computational Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Simon Sprenger
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Mehrshad Pakdel
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Georg F Vogel
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Division of Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Gloria Jih
- Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Wesley Skillern
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States
| | - Reza Behrouzi
- Department of Cell Biology, Harvard Medical School, Boston, United States
| | - Markus Babst
- Department of Biology, University of Utah, Utah, United States.,Center for Cell and Genome Science, University of Utah, Utah, United States
| | - Oliver Schmidt
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael W Hess
- Division of Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - John Ag Briggs
- Structural and Computational Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Tomas Kirchhausen
- Department of Pediatrics, Harvard Medical School, Boston, United States.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, United States.,Department of Cell Biology, Harvard Medical School, Boston, United States
| | - David Teis
- Division of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.,Austrian Drug Screening Institute, Innsbruck, Austria
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41
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Katanin spiral and ring structures shed light on power stroke for microtubule severing. Nat Struct Mol Biol 2017; 24:717-725. [PMID: 28783150 PMCID: PMC7152510 DOI: 10.1038/nsmb.3448] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/07/2017] [Indexed: 01/07/2023]
Abstract
Microtubule-severing enzymes katanin, spastin and fidgetin are AAA ATPases important for the biogenesis and maintenance of complex microtubule arrays in axons, spindles and cilia. Because of a lack of known 3D structures for these enzymes, their mechanism of action has remained poorly understood. Here we report the X-ray crystal structure of the monomeric AAA katanin module from Caenorhabditis elegans and cryo-EM reconstructions of the hexamer in two conformations. The structures reveal an unexpected asymmetric arrangement of the AAA domains mediated by structural elements unique to microtubule-severing enzymes and critical for their function. The reconstructions show that katanin cycles between open spiral and closed ring conformations, depending on the ATP occupancy of a gating protomer that tenses or relaxes interprotomer interfaces. Cycling of the hexamer between these conformations would provide the power stroke for microtubule severing.
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42
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Deville C, Carroni M, Franke KB, Topf M, Bukau B, Mogk A, Saibil HR. Structural pathway of regulated substrate transfer and threading through an Hsp100 disaggregase. SCIENCE ADVANCES 2017; 3:e1701726. [PMID: 28798962 PMCID: PMC5544394 DOI: 10.1126/sciadv.1701726] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/05/2017] [Indexed: 05/03/2023]
Abstract
Refolding aggregated proteins is essential in combating cellular proteotoxic stress. Together with Hsp70, Hsp100 chaperones, including Escherichia coli ClpB, form a powerful disaggregation machine that threads aggregated polypeptides through the central pore of tandem adenosine triphosphatase (ATPase) rings. To visualize protein disaggregation, we determined cryo-electron microscopy structures of inactive and substrate-bound ClpB in the presence of adenosine 5'-O-(3-thiotriphosphate), revealing closed AAA+ rings with a pronounced seam. In the substrate-free state, a marked gradient of resolution, likely corresponding to mobility, spans across the AAA+ rings with a dynamic hotspot at the seam. On the seam side, the coiled-coil regulatory domains are locked in a horizontal, inactive orientation. On the opposite side, the regulatory domains are accessible for Hsp70 binding, substrate targeting, and activation. In the presence of the model substrate casein, the polypeptide threads through the entire pore channel and increased nucleotide occupancy correlates with higher ATPase activity. Substrate-induced domain displacements indicate a pathway of regulated substrate transfer from Hsp70 to the ClpB pore, inside which a spiral of loops contacts the substrate. The seam pore loops undergo marked displacements, along with ordering of the regulatory domains. These asymmetric movements suggest a mechanism for ATPase activation and substrate threading during disaggregation.
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Affiliation(s)
- Célia Deville
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Marta Carroni
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Kamila B. Franke
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Maya Topf
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Bernd Bukau
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of the Heidelberg University, German Cancer Research Center, Heidelberg, Germany
| | - Helen R. Saibil
- Department of Crystallography, Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
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43
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Addressing preferred specimen orientation in single-particle cryo-EM through tilting. Nat Methods 2017; 14:793-796. [PMID: 28671674 DOI: 10.1038/nmeth.4347] [Citation(s) in RCA: 558] [Impact Index Per Article: 79.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/18/2017] [Indexed: 12/18/2022]
Abstract
We present a strategy for tackling preferred specimen orientation in single-particle cryogenic electron microscopy by employing tilts during data collection. We also describe a tool to quantify the resulting directional resolution using 3D Fourier shell correlation volumes. We applied these methods to determine the structures at near-atomic resolution of the influenza hemagglutinin trimer, which adopts a highly preferred specimen orientation, and of ribosomal biogenesis intermediates, which adopt moderately preferred orientations.
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