1
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Banerjee A, Mathew S, Naqvi MM, Yilmaz SZ, Zacharopoulou M, Doruker P, Kumita JR, Yang SH, Gur M, Itzhaki LS, Gordon R, Bahar I. Influence of point mutations on PR65 conformational adaptability: Insights from molecular simulations and nanoaperture optical tweezers. SCIENCE ADVANCES 2024; 10:eadn2208. [PMID: 38820156 PMCID: PMC11141623 DOI: 10.1126/sciadv.adn2208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 04/29/2024] [Indexed: 06/02/2024]
Abstract
PR65 is the HEAT repeat scaffold subunit of the heterotrimeric protein phosphatase 2A (PP2A) and an archetypal tandem repeat protein. Its conformational mechanics plays a crucial role in PP2A function by opening/closing substrate binding/catalysis interface. Using in silico saturation mutagenesis, we identified PR65 "hinge" residues whose substitutions could alter its conformational adaptability and thereby PP2A function, and selected six mutations that were verified to be expressed and soluble. Molecular simulations and nanoaperture optical tweezers revealed consistent results on the specific effects of the mutations on the structure and dynamics of PR65. Two mutants observed in simulations to stabilize extended/open conformations exhibited higher corner frequencies and lower translational scattering in experiments, indicating a shift toward extended conformations, whereas another displayed the opposite features, confirmed by both simulations and experiments. The study highlights the power of single-molecule nanoaperture-based tweezers integrated with in silico approaches for exploring the effect of mutations on protein structure and dynamics.
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Affiliation(s)
- Anupam Banerjee
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Samuel Mathew
- Department of Electrical and Computer Engineering, University of Victoria, Victoria V8P 5C2, Canada
| | - Mohsin M. Naqvi
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Sema Z. Yilmaz
- Department of Mechanical Engineering, Istanbul Technical University, 34437 Istanbul, Turkey
| | - Maria Zacharopoulou
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Pemra Doruker
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Janet R. Kumita
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Shang-Hua Yang
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Mert Gur
- Department of Mechanical Engineering, Istanbul Technical University, 34437 Istanbul, Turkey
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Laura S. Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Reuven Gordon
- Department of Electrical and Computer Engineering, University of Victoria, Victoria V8P 5C2, Canada
| | - Ivet Bahar
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
- Department of Biochemistry and Cell Biology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
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2
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Li L, Liu X, Yang S, Li M, Wu Y, Hu S, Wang W, Jiang A, Zhang Q, Zhang J, Ma X, Hu J, Zhao Q, Liu Y, Li D, Hu J, Yang C, Feng W, Wang X. The HEAT repeat protein HPO-27 is a lysosome fission factor. Nature 2024; 628:630-638. [PMID: 38538795 DOI: 10.1038/s41586-024-07249-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/28/2024] [Indexed: 04/06/2024]
Abstract
Lysosomes are degradation and signalling centres crucial for homeostasis, development and ageing1. To meet diverse cellular demands, lysosomes remodel their morphology and function through constant fusion and fission2,3. Little is known about the molecular basis of fission. Here we identify HPO-27, a conserved HEAT repeat protein, as a lysosome scission factor in Caenorhabditis elegans. Loss of HPO-27 impairs lysosome fission and leads to an excessive tubular network that ultimately collapses. HPO-27 and its human homologue MROH1 are recruited to lysosomes by RAB-7 and enriched at scission sites. Super-resolution imaging, negative-staining electron microscopy and in vitro reconstitution assays reveal that HPO-27 and MROH1 self-assemble to mediate the constriction and scission of lysosomal tubules in worms and mammalian cells, respectively, and assemble to sever supported membrane tubes in vitro. Loss of HPO-27 affects lysosomal morphology, integrity and degradation activity, which impairs animal development and longevity. Thus, HPO-27 and MROH1 act as self-assembling scission factors to maintain lysosomal homeostasis and function.
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Affiliation(s)
- Letao Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
| | - Xilu Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shanshan Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Meijiao Li
- State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
- Southwest United Graduate School, Kunming, China
| | - Yanwei Wu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Siqi Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wenjuan Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Amin Jiang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Qianqian Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Junbing Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaoli Ma
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Junyan Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Qiaohong Zhao
- State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
| | - Yubing Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chonglin Yang
- State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
- Southwest United Graduate School, Kunming, China
| | - Wei Feng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
| | - Xiaochen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
- Southwest United Graduate School, Kunming, China.
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong, China.
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3
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Kaynak BT, Dahmani ZL, Doruker P, Banerjee A, Yang SH, Gordon R, Itzhaki LS, Bahar I. Cooperative mechanics of PR65 scaffold underlies the allosteric regulation of the phosphatase PP2A. Structure 2023; 31:607-618.e3. [PMID: 36948205 PMCID: PMC10164121 DOI: 10.1016/j.str.2023.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/25/2023] [Accepted: 02/23/2023] [Indexed: 03/24/2023]
Abstract
PR65, a horseshoe-shaped scaffold composed of 15 HEAT (observed in Huntingtin, elongation factor 3, protein phosphatase 2A, and the yeast kinase TOR1) repeats, forms, together with catalytic and regulatory subunits, the heterotrimeric protein phosphatase PP2A. We examined the role of PR65 in enabling PP2A enzymatic activity with computations at various levels of complexity, including hybrid approaches that combine full-atomic and elastic network models. Our study points to the high flexibility of this scaffold allowing for end-to-end distance fluctuations of 40-50 Å between compact and extended conformations. Notably, the intrinsic dynamics of PR65 facilitates complexation with the catalytic subunit and is retained in the PP2A complex enabling PR65 to engage the two domains of the catalytic subunit and provide the mechanical framework for enzymatic activity, with support from the regulatory subunit. In particular, the intra-repeat coils at the C-terminal arm play an important role in allosterically mediating the collective dynamics of PP2A, pointing to target sites for modulating PR65 function.
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Affiliation(s)
- Burak T Kaynak
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA; Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Zakaria L Dahmani
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Pemra Doruker
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Anupam Banerjee
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA; Laufer Center for Physical and Quantitative Biology, and Department of Biochemistry and Cell Biology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Shang-Hua Yang
- Department of Electrical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Reuven Gordon
- Department of Electrical and Computer Engineering, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Ivet Bahar
- Laufer Center for Physical and Quantitative Biology, and Department of Biochemistry and Cell Biology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA.
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4
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A topological data analytic approach for discovering biophysical signatures in protein dynamics. PLoS Comput Biol 2022; 18:e1010045. [PMID: 35500014 PMCID: PMC9098046 DOI: 10.1371/journal.pcbi.1010045] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 05/12/2022] [Accepted: 03/22/2022] [Indexed: 12/02/2022] Open
Abstract
Identifying structural differences among proteins can be a non-trivial task. When contrasting ensembles of protein structures obtained from molecular dynamics simulations, biologically-relevant features can be easily overshadowed by spurious fluctuations. Here, we present SINATRA Pro, a computational pipeline designed to robustly identify topological differences between two sets of protein structures. Algorithmically, SINATRA Pro works by first taking in the 3D atomic coordinates for each protein snapshot and summarizing them according to their underlying topology. Statistically significant topological features are then projected back onto a user-selected representative protein structure, thus facilitating the visual identification of biophysical signatures of different protein ensembles. We assess the ability of SINATRA Pro to detect minute conformational changes in five independent protein systems of varying complexities. In all test cases, SINATRA Pro identifies known structural features that have been validated by previous experimental and computational studies, as well as novel features that are also likely to be biologically-relevant according to the literature. These results highlight SINATRA Pro as a promising method for facilitating the non-trivial task of pattern recognition in trajectories resulting from molecular dynamics simulations, with substantially increased resolution. Structural features of proteins often serve as signatures of their biological function and molecular binding activity. Elucidating these structural features is essential for a full understanding of underlying biophysical mechanisms. While there are existing methods aimed at identifying structural differences between protein variants, such methods do not have the capability to jointly infer both geometric and dynamic changes, simultaneously. In this paper, we propose SINATRA Pro, a computational framework for extracting key structural features between two sets of proteins. SINATRA Pro robustly outperforms standard techniques in pinpointing the physical locations of both static and dynamic signatures across various types of protein ensembles, and it does so with improved resolution.
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5
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Basu S, Rajendra KC, Alagar S, Bahadur RP. Impaired nuclear transport induced by juvenile ALS causing P525L mutation in NLS domain of FUS: A molecular mechanistic study. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140766. [PMID: 35134572 DOI: 10.1016/j.bbapap.2022.140766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 01/15/2022] [Accepted: 01/28/2022] [Indexed: 12/30/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and fronto-temporal lobar degeneration (FTLD) are progressive neurological disorders affecting motor neurons. Cellular aggregates of fused in sarcoma (FUS) protein are found in cytoplasm of ALS and FTLD patients. Nuclear localisation signal (NLS) domain of FUS binds to Karyopherin β2 (Kapβ2), which drives nuclear transport of FUS from cytoplasm. Several pathogenic mutations are reported in FUS NLS, which are associated with its impaired nuclear transport and cytoplasmic mis-localisation. P525L mutation in NLS is most commonly found in cases of juvenile ALS (jALS), which affects individuals below 25 years of age. jALS progresses aggressively causing death within a year of its onset. This study elucidates the molecular mechanism behind jALS-causing P525L mutation hindering nuclear transport of FUS. We perform multiple molecular dynamics simulations in aqueous and hydrophobic solvent to understand the effect of the mutation at molecular level. Dynamics of Kapβ2-FUS complex is better captured in hydrophobic solvent compared to aqueous solvent. P525 and Y526 (PY-motif) of NLS exhibit fine-tuned stereochemical arrangement, which is essential for optimum Kapβ2 binding. P525L causes loss of several native contacts at interface leading to weaker binding, which promotes self-aggregation of FUS in cytoplasm. Native complex samples closed conformation, while mutant complex exhibits open conformation exposing hydrophilic residues of Kapβ2 to hydrophobic solvent. Mutant complex also fails to exhibit spring-like motion essential for its transport through nuclear pore complex. This study provides a mechanistic insight of binding affinity between NLS and Kapβ2 that inhibits self-aggregation of FUS preventing the disease condition.
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Affiliation(s)
- Sushmita Basu
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - K C Rajendra
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Suresh Alagar
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ranjit Prasad Bahadur
- Computational Structural Biology Lab, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
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6
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Synakewicz M, Eapen RS, Perez-Riba A, Rowling PJE, Bauer D, Weißl A, Fischer G, Hyvönen M, Rief M, Itzhaki LS, Stigler J. Unraveling the Mechanics of a Repeat-Protein Nanospring: From Folding of Individual Repeats to Fluctuations of the Superhelix. ACS NANO 2022. [PMID: 35258937 DOI: 10.1101/2021.03.27.437344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Tandem-repeat proteins comprise small secondary structure motifs that stack to form one-dimensional arrays with distinctive mechanical properties that are proposed to direct their cellular functions. Here, we use single-molecule optical tweezers to study the folding of consensus-designed tetratricopeptide repeats (CTPRs), superhelical arrays of short helix-turn-helix motifs. We find that CTPRs display a spring-like mechanical response in which individual repeats undergo rapid equilibrium fluctuations between partially folded and unfolded conformations. We rationalize the force response using Ising models and dissect the folding pathway of CTPRs under mechanical load, revealing how the repeat arrays form from the center toward both termini simultaneously. Most strikingly, we also directly observe the protein's superhelical tertiary structure in the force signal. Using protein engineering, crystallography, and single-molecule experiments, we show that the superhelical geometry can be altered by carefully placed amino acid substitutions, and we examine how these sequence changes affect intrinsic repeat stability and inter-repeat coupling. Our findings provide the means to dissect and modulate repeat-protein stability and dynamics, which will be essential for researchers to understand the function of natural repeat proteins and to exploit artificial repeats proteins in nanotechnology and biomedical applications.
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Affiliation(s)
- Marie Synakewicz
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Rohan S Eapen
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Albert Perez-Riba
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Pamela J E Rowling
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Daniela Bauer
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Andreas Weißl
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Gerhard Fischer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Matthias Rief
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Johannes Stigler
- Gene Center Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 München, Germany
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7
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Synakewicz M, Eapen RS, Perez-Riba A, Rowling PJE, Bauer D, Weißl A, Fischer G, Hyvönen M, Rief M, Itzhaki LS, Stigler J. Unraveling the Mechanics of a Repeat-Protein Nanospring: From Folding of Individual Repeats to Fluctuations of the Superhelix. ACS NANO 2022; 16:3895-3905. [PMID: 35258937 PMCID: PMC8944806 DOI: 10.1021/acsnano.1c09162] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Tandem-repeat proteins comprise small secondary structure motifs that stack to form one-dimensional arrays with distinctive mechanical properties that are proposed to direct their cellular functions. Here, we use single-molecule optical tweezers to study the folding of consensus-designed tetratricopeptide repeats (CTPRs), superhelical arrays of short helix-turn-helix motifs. We find that CTPRs display a spring-like mechanical response in which individual repeats undergo rapid equilibrium fluctuations between partially folded and unfolded conformations. We rationalize the force response using Ising models and dissect the folding pathway of CTPRs under mechanical load, revealing how the repeat arrays form from the center toward both termini simultaneously. Most strikingly, we also directly observe the protein's superhelical tertiary structure in the force signal. Using protein engineering, crystallography, and single-molecule experiments, we show that the superhelical geometry can be altered by carefully placed amino acid substitutions, and we examine how these sequence changes affect intrinsic repeat stability and inter-repeat coupling. Our findings provide the means to dissect and modulate repeat-protein stability and dynamics, which will be essential for researchers to understand the function of natural repeat proteins and to exploit artificial repeats proteins in nanotechnology and biomedical applications.
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Affiliation(s)
- Marie Synakewicz
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Rohan S. Eapen
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Albert Perez-Riba
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Pamela J. E. Rowling
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Daniela Bauer
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Andreas Weißl
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Gerhard Fischer
- Department
of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Marko Hyvönen
- Department
of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Matthias Rief
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Laura S. Itzhaki
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Johannes Stigler
- Gene
Center Munich, Ludwig-Maximilians-Universität
München, Feodor-Lynen-Straße 25, 81377 München, Germany
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8
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Tracy TE, Madero-Pérez J, Swaney DL, Chang TS, Moritz M, Konrad C, Ward ME, Stevenson E, Hüttenhain R, Kauwe G, Mercedes M, Sweetland-Martin L, Chen X, Mok SA, Wong MY, Telpoukhovskaia M, Min SW, Wang C, Sohn PD, Martin J, Zhou Y, Luo W, Trojanowski JQ, Lee VMY, Gong S, Manfredi G, Coppola G, Krogan NJ, Geschwind DH, Gan L. Tau interactome maps synaptic and mitochondrial processes associated with neurodegeneration. Cell 2022; 185:712-728.e14. [PMID: 35063084 PMCID: PMC8857049 DOI: 10.1016/j.cell.2021.12.041] [Citation(s) in RCA: 108] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 10/20/2021] [Accepted: 12/22/2021] [Indexed: 12/21/2022]
Abstract
Tau (MAPT) drives neuronal dysfunction in Alzheimer disease (AD) and other tauopathies. To dissect the underlying mechanisms, we combined an engineered ascorbic acid peroxidase (APEX) approach with quantitative affinity purification mass spectrometry (AP-MS) followed by proximity ligation assay (PLA) to characterize Tau interactomes modified by neuronal activity and mutations that cause frontotemporal dementia (FTD) in human induced pluripotent stem cell (iPSC)-derived neurons. We established interactions of Tau with presynaptic vesicle proteins during activity-dependent Tau secretion and mapped the Tau-binding sites to the cytosolic domains of integral synaptic vesicle proteins. We showed that FTD mutations impair bioenergetics and markedly diminished Tau’s interaction with mitochondria proteins, which were downregulated in AD brains of multiple cohorts and correlated with disease severity. These multimodal and dynamic Tau interactomes with exquisite spatial resolution shed light on Tau’s role in neuronal function and disease and highlight potential therapeutic targets to block Tau-mediated pathogenesis. By combining APEX and AP-MS proteomic approaches, Tau interactome mapping reveals that Tau interactors are modified by neuronal activity and FTD mutations in human iPSC-derived neurons.
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Affiliation(s)
- Tara E Tracy
- Gladstone Institutes, San Francisco, CA 94158, USA; Buck Institute for Research on Aging, Novato, CA 94945, USA.
| | - Jesus Madero-Pérez
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA.
| | - Danielle L Swaney
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Timothy S Chang
- Department of Neurology, Movement Disorders Program and Program in Neurogenetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Michelle Moritz
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA
| | - Csaba Konrad
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | | | - Erica Stevenson
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ruth Hüttenhain
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
| | - Grant Kauwe
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Maria Mercedes
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Lauren Sweetland-Martin
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Xu Chen
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Sue-Ann Mok
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Man Ying Wong
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | | | - Sang-Won Min
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Chao Wang
- Gladstone Institutes, San Francisco, CA 94158, USA
| | | | | | - Yungui Zhou
- Gladstone Institutes, San Francisco, CA 94158, USA
| | - Wenjie Luo
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - John Q Trojanowski
- Center for Neurodegenerative Disease Research, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Virginia M Y Lee
- Center for Neurodegenerative Disease Research, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shiaoching Gong
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA
| | - Giovanni Coppola
- Department of Neurology, Movement Disorders Program and Program in Neurogenetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, CA 90095, USA
| | - Nevan J Krogan
- Gladstone Institutes, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; Quantitative Biosciences Institute (QBI), University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daniel H Geschwind
- Department of Neurology, Movement Disorders Program and Program in Neurogenetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Institute of Precision Health, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Li Gan
- Helen and Robert Appel Alzheimer Disease Research Institute, Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA.
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9
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Lu J, Wu T, Zhang B, Liu S, Song W, Qiao J, Ruan H. Types of nuclear localization signals and mechanisms of protein import into the nucleus. Cell Commun Signal 2021; 19:60. [PMID: 34022911 PMCID: PMC8140498 DOI: 10.1186/s12964-021-00741-y] [Citation(s) in RCA: 136] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 04/16/2021] [Indexed: 12/28/2022] Open
Abstract
Nuclear localization signals (NLS) are generally short peptides that act as a signal fragment that mediates the transport of proteins from the cytoplasm into the nucleus. This NLS-dependent protein recognition, a process necessary for cargo proteins to pass the nuclear envelope through the nuclear pore complex, is facilitated by members of the importin superfamily. Here, we summarized the types of NLS, focused on the recently reported related proteins containing nuclear localization signals, and briefly summarized some mechanisms that do not depend on nuclear localization signals into the nucleus. Video Abstract.
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Affiliation(s)
- Juane Lu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Tao Wu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Biao Zhang
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Suke Liu
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Wenjun Song
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
| | - Jianjun Qiao
- Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin, China
- Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
| | - Haihua Ruan
- Tianjin Key Laboratory of Food Science and Biotechnology, College of Biotechnology and Food Science, Tianjin University of Commerce, Tianjin, China
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10
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The Role of Protein Disorder in Nuclear Transport and in Its Subversion by Viruses. Cells 2020; 9:cells9122654. [PMID: 33321790 PMCID: PMC7764567 DOI: 10.3390/cells9122654] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/08/2020] [Accepted: 12/08/2020] [Indexed: 12/12/2022] Open
Abstract
The transport of host proteins into and out of the nucleus is key to host function. However, nuclear transport is restricted by nuclear pores that perforate the nuclear envelope. Protein intrinsic disorder is an inherent feature of this selective transport barrier and is also a feature of the nuclear transport receptors that facilitate the active nuclear transport of cargo, and the nuclear transport signals on the cargo itself. Furthermore, intrinsic disorder is an inherent feature of viral proteins and viral strategies to disrupt host nucleocytoplasmic transport to benefit their replication. In this review, we highlight the role that intrinsic disorder plays in the nuclear transport of host and viral proteins. We also describe viral subversion mechanisms of the host nuclear transport machinery in which intrinsic disorder is a feature. Finally, we discuss nuclear import and export as therapeutic targets for viral infectious disease.
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11
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Díaz-García C, Hornos F, Giudici AM, Cámara-Artigas A, Luque-Ortega JR, Arbe A, Rizzuti B, Alfonso C, Forwood JK, Iovanna JL, Gómez J, Prieto M, Coutinho A, Neira JL. Human importin α3 and its N-terminal truncated form, without the importin-β-binding domain, are oligomeric species with a low conformational stability in solution. Biochim Biophys Acta Gen Subj 2020; 1864:129609. [PMID: 32234409 DOI: 10.1016/j.bbagen.2020.129609] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 03/13/2020] [Accepted: 03/26/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Eukaryotic cells have a continuous transit of macromolecules between the cytoplasm and the nucleus. Several carrier proteins are involved in this transport. One of them is importin α, which must form a complex with importin β to accomplish its function, by domain-swapping its 60-residue-long N terminus. There are several human isoforms of importin α; among them, importin α3 has a particularly high flexibility. METHODS We studied the conformational stability of intact importin α3 (Impα3) and its truncated form, where the 64-residue-long, N-terminal importin-β-binding domain (IBB) has been removed (ΔImpα3), in a wide pH range, with several spectroscopic, biophysical, biochemical methods and with molecular dynamics (MD). RESULTS Both species acquired native-like structure between pH 7 and 10.0, where Impα3 was a dimer (with an apparent self-association constant of ~10 μM) and ΔImpα3 had a higher tendency to self-associate than the intact species. The acquisition of secondary, tertiary and quaternary structure, and the burial of hydrophobic patches, occurred concomitantly. Both proteins unfolded irreversibly at physiological pH, by using either temperature or chemical denaturants, through several partially folded intermediates. The MD simulations support the presence of these intermediates. CONCLUSIONS The thermal stability of Impα3 at physiological pH was very low, but was higher than that of ΔImpα3. Both proteins were stable in a narrow pH range, and they unfolded at physiological pH populating several intermediate species. GENERAL SIGNIFICANCE The low conformational stability explains the flexibility of Impα3, which is needed to carry out its recognition of complex cargo sequences.
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Affiliation(s)
- Clara Díaz-García
- iBB- Institute for Bioengineering and Bioscience, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisboa, Portugal
| | - Felipe Hornos
- IDIBE, Universidad Miguel Hernández, 03202 Elche, Alicante, Spain
| | | | - Ana Cámara-Artigas
- Departamento de Química y Física, Research Center CIAIMBITAL, Universidad de Almería- ceiA3, 04120 Almería, Spain
| | - Juan Román Luque-Ortega
- Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Arantxa Arbe
- Centro de Física de Materiales (CFM) (CSIC-UPV/EHU), Materials Physics Center (MPC), 20018 San Sebastián, Spain
| | - Bruno Rizzuti
- CNR-NANOTEC, Licryl-UOS Cosenza and CEMIF.Cal, Department of Physics, University of Calabria, Via P. Bucci, Cubo 31 C, 87036 Arcavacata di Rende, Cosenza, Italy
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas Margarita Salas (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
| | - Juan L Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13288 Marseille, France
| | - Javier Gómez
- IDIBE, Universidad Miguel Hernández, 03202 Elche, Alicante, Spain
| | - Manuel Prieto
- iBB- Institute for Bioengineering and Bioscience, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisboa, Portugal
| | - Ana Coutinho
- iBB- Institute for Bioengineering and Bioscience, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisboa, Portugal; Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisboa, Portugal
| | - José L Neira
- IDIBE, Universidad Miguel Hernández, 03202 Elche, Alicante, Spain; Instituto de Biocomputación y Física de Sistemas Complejos, Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50009 Zaragoza, Spain.
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12
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Yang SNY, Atkinson SC, Wang C, Lee A, Bogoyevitch MA, Borg NA, Jans DA. The broad spectrum antiviral ivermectin targets the host nuclear transport importin α/β1 heterodimer. Antiviral Res 2020; 177:104760. [PMID: 32135219 DOI: 10.1016/j.antiviral.2020.104760] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Infection by RNA viruses such as human immunodeficiency virus (HIV)-1, influenza, and dengue virus (DENV) represent a major burden for human health worldwide. Although RNA viruses replicate in the infected host cell cytoplasm, the nucleus is central to key stages of the infectious cycle of HIV-1 and influenza, and an important target of DENV nonstructural protein 5 (NS5) in limiting the host antiviral response. We previously identified the small molecule ivermectin as an inhibitor of HIV-1 integrase nuclear entry, subsequently showing ivermectin could inhibit DENV NS5 nuclear import, as well as limit infection by viruses such as HIV-1 and DENV. We show here that ivermectin's broad spectrum antiviral activity relates to its ability to target the host importin (IMP) α/β1 nuclear transport proteins responsible for nuclear entry of cargoes such as integrase and NS5. We establish for the first time that ivermectin can dissociate the preformed IMPα/β1 heterodimer, as well as prevent its formation, through binding to the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity. We show that ivermectin inhibits NS5-IMPα interaction in a cell context using quantitative bimolecular fluorescence complementation. Finally, we show for the first time that ivermectin can limit infection by the DENV-related West Nile virus at low (μM) concentrations. Since it is FDA approved for parasitic indications, ivermectin merits closer consideration as a broad spectrum antiviral of interest.
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Affiliation(s)
- Sundy N Y Yang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Sarah C Atkinson
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Chunxiao Wang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Alexander Lee
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Marie A Bogoyevitch
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Australia
| | - Natalie A Borg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - David A Jans
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia.
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13
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Llabrés S, Tsenkov MI, MacGowan SA, Barton GJ, Zachariae U. Disease related single point mutations alter the global dynamics of a tetratricopeptide (TPR) α-solenoid domain. J Struct Biol 2020; 209:107405. [PMID: 31628985 PMCID: PMC6961204 DOI: 10.1016/j.jsb.2019.107405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 10/04/2019] [Accepted: 10/15/2019] [Indexed: 01/18/2023]
Abstract
Tetratricopeptide repeat (TPR) proteins belong to the class of α-solenoid proteins, in which repetitive units of α-helical hairpin motifs stack to form superhelical, often highly flexible structures. TPR domains occur in a wide variety of proteins, and perform key functional roles including protein folding, protein trafficking, cell cycle control and post-translational modification. Here, we look at the TPR domain of the enzyme O-linked GlcNAc-transferase (OGT), which catalyses O-GlcNAcylation of a broad range of substrate proteins. A number of single-point mutations in the TPR domain of human OGT have been associated with the disease Intellectual Disability (ID). By extended steered and equilibrium atomistic simulations, we show that the OGT-TPR domain acts as an elastic nanospring, and that each of the ID-related local mutations substantially affect the global dynamics of the TPR domain. Since the nanospring character of the OGT-TPR domain is key to its function in binding and releasing OGT substrates, these changes of its biomechanics likely lead to defective substrate interaction. We find that neutral mutations in the human population, selected by analysis of the gnomAD database, do not incur these changes. Our findings may not only help to explain the ID phenotype of the mutants, but also aid the design of TPR proteins with tailored biomechanical properties.
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Affiliation(s)
- Salomé Llabrés
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK.
| | - Maxim I Tsenkov
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Stuart A MacGowan
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Geoffrey J Barton
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Ulrich Zachariae
- Computational Biology, School of Life Sciences, University of Dundee, Dundee, UK; Physics, School of Science and Engineering, University of Dundee, Dundee, UK.
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14
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Disclosing the Impact of Carcinogenic SF3b Mutations on Pre-mRNA Recognition Via All-Atom Simulations. Biomolecules 2019; 9:biom9100633. [PMID: 31640290 PMCID: PMC6843770 DOI: 10.3390/biom9100633] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/15/2019] [Accepted: 10/17/2019] [Indexed: 02/07/2023] Open
Abstract
The spliceosome accurately promotes precursor messenger-RNA splicing by recognizing specific noncoding intronic tracts including the branch point sequence (BPS) and the 3'-splice-site (3'SS). Mutations of Hsh155 (yeast)/SF3B1 (human), which is a protein of the SF3b factor involved in BPS recognition and induces altered BPS binding and 3'SS selection, lead to mis-spliced mRNA transcripts. Although these mutations recur in hematologic malignancies, the mechanism by which they change gene expression remains unclear. In this study, multi-microsecond-long molecular-dynamics simulations of eighth distinct ∼700,000 atom models of the spliceosome Bact complex, and gene sequencing of SF3B1, disclose that these carcinogenic isoforms destabilize intron binding and/or affect the functional dynamics of Hsh155/SF3B1 only when binding non-consensus BPSs, as opposed to the non-pathogenic variants newly annotated here. This pinpoints a cross-talk between the distal Hsh155 mutation and BPS recognition sites. Our outcomes unprecedentedly contribute to elucidating the principles of pre-mRNA recognition, which provides critical insights on the mechanism underlying constitutive/alternative/aberrant splicing.
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15
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Tessier TM, Dodge MJ, Prusinkiewicz MA, Mymryk JS. Viral Appropriation: Laying Claim to Host Nuclear Transport Machinery. Cells 2019; 8:E559. [PMID: 31181773 PMCID: PMC6627039 DOI: 10.3390/cells8060559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022] Open
Abstract
Protein nuclear transport is an integral process to many cellular pathways and often plays a critical role during viral infection. To overcome the barrier presented by the nuclear membrane and gain access to the nucleus, virally encoded proteins have evolved ways to appropriate components of the nuclear transport machinery. By binding karyopherins, or the nuclear pore complex, viral proteins influence their own transport as well as the transport of key cellular regulatory proteins. This review covers how viral proteins can interact with different components of the nuclear import machinery and how this influences viral replicative cycles. We also highlight the effects that viral perturbation of nuclear transport has on the infected host and how we can exploit viruses as tools to study novel mechanisms of protein nuclear import. Finally, we discuss the possibility that drugs targeting these transport pathways could be repurposed for treating viral infections.
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Affiliation(s)
- Tanner M Tessier
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Mackenzie J Dodge
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Martin A Prusinkiewicz
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Joe S Mymryk
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
- Department of Otolaryngology, Head & Neck Surgery, The University of Western Ontario, London, ON N6A 3K7, Canada.
- Department of Oncology, The University of Western Ontario, London, ON N6A 3K7, Canada.
- London Regional Cancer Program, Lawson Health Research Institute, London, ON N6A 5W9, Canada.
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16
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Yang SNY, Atkinson SC, Fraser JE, Wang C, Maher B, Roman N, Forwood JK, Wagstaff KM, Borg NA, Jans DA. Novel Flavivirus Antiviral That Targets the Host Nuclear Transport Importin α/β1 Heterodimer. Cells 2019; 8:cells8030281. [PMID: 30909636 PMCID: PMC6468590 DOI: 10.3390/cells8030281] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 12/20/2022] Open
Abstract
Dengue virus (DENV) threatens almost 70% of the world’s population, with no effective vaccine or therapeutic currently available. A key contributor to infection is nuclear localisation in the infected cell of DENV nonstructural protein 5 (NS5) through the action of the host importin (IMP) α/β1 proteins. Here, we used a range of microscopic, virological and biochemical/biophysical approaches to show for the first time that the small molecule GW5074 has anti-DENV action through its novel ability to inhibit NS5–IMPα/β1 interaction in vitro as well as NS5 nuclear localisation in infected cells. Strikingly, GW5074 not only inhibits IMPα binding to IMPβ1, but can dissociate preformed IMPα/β1 heterodimer, through targeting the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity, as shown using analytical ultracentrifugation, thermostability analysis and circular dichroism measurements. Importantly, GW5074 has strong antiviral activity at low µM concentrations against not only DENV-2, but also zika virus and West Nile virus. This work highlights DENV NS5 nuclear targeting as a viable target for anti-flaviviral therapeutics.
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Affiliation(s)
- Sundy N Y Yang
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Sarah C Atkinson
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Johanna E Fraser
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Chunxiao Wang
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Belinda Maher
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Noelia Roman
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia.
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW 2650, Australia.
| | - Kylie M Wagstaff
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - Natalie A Borg
- Infection & Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
| | - David A Jans
- Nuclear Signaling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic. 3800, Australia.
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17
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Duan Z, Xu H, Ji X, Zhao J, Xu H, Hu Y, Deng S, Hu S, Liu X. Importin α5 negatively regulates importin β1-mediated nuclear import of Newcastle disease virus matrix protein and viral replication and pathogenicity in chicken fibroblasts. Virulence 2018. [PMID: 29532715 PMCID: PMC5955436 DOI: 10.1080/21505594.2018.1449507] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The matrix (M) protein of Newcastle disease virus (NDV) is demonstrated to localize in the nucleus via intrinsic nuclear localization signal (NLS), but cellular proteins involved in the nuclear import of NDV M protein and the role of M's nuclear localization in the replication and pathogenicity of NDV remain unclear. In this study, importin β1 was screened to interact with NDV M protein by yeast two-hybrid screening. This interaction was subsequently confirmed by co-immunoprecipitation and pull-down assays. In vitro binding studies indicated that the NLS region of M protein and the amino acids 336–433 of importin β1 that belonged to the RanGTP binding region were important for binding. Importantly, a recombinant virus with M/NLS mutation resulted in a pathotype change of NDV and attenuated viral replication and pathogenicity in chicken fibroblasts and SPF chickens. In agreement with the binding data, nuclear import of NDV M protein in digitonin-permeabilized HeLa cells required both importin β1 and RanGTP. Interestingly, importin α5 was verified to interact with M protein through binding importin β1. However, importin β1 or importin α5 depletion by siRNA resulted in different results, which showed the obviously cytoplasmic or nuclear accumulation of M protein and the remarkably decreased or increased replication ability and pathogenicity of NDV in chicken fibroblasts, respectively. Our findings therefore demonstrate for the first time the nuclear import mechanism of NDV M protein and the negative regulation role of importin α5 in importin β1-mediated nuclear import of M protein and the replication and pathogenicity of a paramyxovirus.
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Affiliation(s)
- Zhiqiang Duan
- a Key Laboratory of Animal Genetics, Breeding and Reproduction in The Plateau Mountainous Region, Ministry of Education , Guizhou University , Guiyang , China.,b College of Animal Science , Guizhou University , Guiyang , China
| | - Haixu Xu
- c Key Laboratory of Animal Infectious Diseases of Ministry of Agriculture , Yangzhou University , Yangzhou , China
| | - Xinqin Ji
- a Key Laboratory of Animal Genetics, Breeding and Reproduction in The Plateau Mountainous Region, Ministry of Education , Guizhou University , Guiyang , China.,b College of Animal Science , Guizhou University , Guiyang , China
| | - Jiafu Zhao
- a Key Laboratory of Animal Genetics, Breeding and Reproduction in The Plateau Mountainous Region, Ministry of Education , Guizhou University , Guiyang , China.,b College of Animal Science , Guizhou University , Guiyang , China
| | - Houqiang Xu
- a Key Laboratory of Animal Genetics, Breeding and Reproduction in The Plateau Mountainous Region, Ministry of Education , Guizhou University , Guiyang , China.,b College of Animal Science , Guizhou University , Guiyang , China
| | - Yan Hu
- b College of Animal Science , Guizhou University , Guiyang , China
| | - Shanshan Deng
- b College of Animal Science , Guizhou University , Guiyang , China
| | - Shunlin Hu
- c Key Laboratory of Animal Infectious Diseases of Ministry of Agriculture , Yangzhou University , Yangzhou , China
| | - Xiufan Liu
- c Key Laboratory of Animal Infectious Diseases of Ministry of Agriculture , Yangzhou University , Yangzhou , China
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18
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Papasergi-Scott MM, Stoveken HM, MacConnachie L, Chan PY, Gabay M, Wong D, Freeman RS, Beg AA, Tall GG. Dual phosphorylation of Ric-8A enhances its ability to mediate G protein α subunit folding and to stimulate guanine nucleotide exchange. Sci Signal 2018; 11:11/532/eaap8113. [PMID: 29844055 DOI: 10.1126/scisignal.aap8113] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Resistance to inhibitors of cholinesterase-8A (Ric-8A) and Ric-8B are essential biosynthetic chaperones for heterotrimeric G protein α subunits. We provide evidence for the direct regulation of Ric-8A cellular activity by dual phosphorylation. Using proteomics, Western blotting, and mutational analyses, we determined that Ric-8A was constitutively phosphorylated at five serines and threonines by the protein kinase CK2. Phosphorylation of Ser435 and Thr440 in rat Ric-8A (corresponding to Ser436 and Thr441 in human Ric-8A) was required for high-affinity binding to Gα subunits, efficient stimulation of Gα subunit guanine nucleotide exchange, and mediation of Gα subunit folding. The CK2 consensus sites that contain Ser435 and Thr440 are conserved in Ric-8 homologs from worms to mammals. We found that the homologous residues in mouse Ric-8B, Ser468 and Ser473, were also phosphorylated. Mutation of the genomic copy of ric-8 in Caenorhabditis elegans to encode alanine in the homologous sites resulted in characteristic ric-8 reduction-of-function phenotypes that are associated with defective Gq and Gs signaling, including reduced locomotion and defective egg laying. The C. elegans ric-8 phosphorylation site mutant phenotypes were partially rescued by chemical stimulation of Gq signaling. These results indicate that dual phosphorylation represents a critical form of conserved Ric-8 regulation and demonstrate that Ric-8 proteins are needed for effective Gα signaling. The position of the CK2-phosphorylated sites within a structural model of Ric-8A reveals that these sites contribute to a key acidic and negatively charged surface that may be important for its interactions with Gα subunits.
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Affiliation(s)
- Makaía M Papasergi-Scott
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Hannah M Stoveken
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lauren MacConnachie
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Pui-Yee Chan
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Meital Gabay
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Dorothy Wong
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Robert S Freeman
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Asim A Beg
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Gregory G Tall
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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19
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Curvature of designed armadillo repeat proteins allows modular peptide binding. J Struct Biol 2018; 201:108-117. [DOI: 10.1016/j.jsb.2017.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/15/2017] [Accepted: 08/28/2017] [Indexed: 11/17/2022]
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20
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Duan Z, Zhao J, Xu H, Xu H, Ji X, Chen X, Xiong J. Characterization of the nuclear import pathway for BLM protein. Arch Biochem Biophys 2017; 634:57-68. [PMID: 29017749 DOI: 10.1016/j.abb.2017.09.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 01/13/2023]
Abstract
Numerous studies have shown that nuclear localization of BLM protein, a member of the RecQ helicases, mediated by nuclear localization signal (NLS) is critical for DNA recombination, replication and transcription, but the mechanism by which BLM protein is imported into the nucleus remains unknown. In this study, the nuclear import pathway for BLM was investigated. We found that nuclear import of BLM was inhibited by two dominant-negative mutants of importin β1 and NTF2/E42K, which lacks the ability to bind Ran and RanGDP, respectively, but was not inhibited by the Ran/Q69L, which is deficient in GTP hydrolysis. Further studies revealed that nuclear import of BLM was reconstituted using importin β1, RanGDP and NTF2 in digitonin-permeabilized HeLa cells. Moreover, BLM had direct binding to importin β1 through its NLS domain with the 14-16 HEAT repeats of importin β1. Furthermore, importin β1, Ran or NTF2 depletion by siRNA disrupted the accumulation of BLM protein in the nucleus. These results showed that BLM enters the nucleus via the importin β1, RanGDP and NTF2 dependent pathway, demonstrating for the first time the nuclear trafficking mechanism of a DNA helicase.
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Affiliation(s)
- Zhiqiang Duan
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Animal Science, Guizhou University, Guiyang 550025, China
| | - Jiafu Zhao
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Animal Science, Guizhou University, Guiyang 550025, China
| | - Houqiang Xu
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Animal Science, Guizhou University, Guiyang 550025, China.
| | - Haixu Xu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China
| | - Xinqin Ji
- College of Animal Science, Guizhou University, Guiyang 550025, China
| | - Xiang Chen
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, Guizhou University, Guiyang 550025, China; College of Animal Science, Guizhou University, Guiyang 550025, China
| | - Jianming Xiong
- College of Animal Science, Guizhou University, Guiyang 550025, China
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21
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Kapinos LE, Huang B, Rencurel C, Lim RYH. Karyopherins regulate nuclear pore complex barrier and transport function. J Cell Biol 2017; 216:3609-3624. [PMID: 28864541 PMCID: PMC5674887 DOI: 10.1083/jcb.201702092] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 06/16/2017] [Accepted: 08/08/2017] [Indexed: 01/01/2023] Open
Abstract
Kapinos et al. show that nuclear pore complex permeability and cargo release functionalities are concomitantly regulated by karyopherin occupancy and turnover in a systematic continuum. This highlights increasingly important roles for the soluble nucleocytoplasmic transport machinery that depart from established views of the nuclear pore complex selectivity mechanism. Nucleocytoplasmic transport is sustained by karyopherins (Kaps) and a Ran guanosine triphosphate (RanGTP) gradient that imports nuclear localization signal (NLS)–specific cargoes (NLS-cargoes) into the nucleus. However, how nuclear pore complex (NPC) barrier selectivity, Kap traffic, and NLS-cargo release are systematically linked and simultaneously regulated remains incoherent. In this study, we show that Kapα facilitates Kapβ1 turnover and occupancy at the NPC in a RanGTP-dependent manner that is directly coupled to NLS-cargo release and NPC barrier function. This is underpinned by the binding affinity of Kapβ1 to phenylalanine–glycine nucleoporins (FG Nups), which is comparable with RanGTP·Kapβ1, but stronger for Kapα·Kapβ1. On this basis, RanGTP is ineffective at releasing standalone Kapβ1 from NPCs. Depleting Kapα·Kapβ1 by RanGTP further abrogates NPC barrier function, whereas adding back Kapβ1 rescues it while Kapβ1 turnover softens it. Therefore, the FG Nups are necessary but insufficient for NPC barrier function. We conclude that Kaps constitute integral constituents of the NPC whose barrier, transport, and cargo release functionalities establish a continuum under a mechanism of Kap-centric control.
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Affiliation(s)
- Larisa E Kapinos
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Binlu Huang
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Chantal Rencurel
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
| | - Roderick Y H Lim
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel, Switzerland
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22
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Gupta A, Kailasam S, Bansal M. Insights into the Structural Dynamics of Nucleocytoplasmic Transport of tRNA by Exportin-t. Biophys J 2016; 110:1264-79. [PMID: 27028637 DOI: 10.1016/j.bpj.2016.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 01/21/2016] [Accepted: 02/05/2016] [Indexed: 12/29/2022] Open
Abstract
Exportin-t (Xpot) transports mature 5'- and 3'-end processed tRNA from the nucleus to the cytoplasm by associating with a small G-protein Ran (RAs-related nuclear protein), in the nucleus. The release of tRNA in cytoplasm involves RanGTP hydrolysis. Despite the availability of crystal structures of nuclear and cytosolic forms of Xpot, the molecular details regarding the sequential events leading to tRNA release and subsequent conformational changes occurring in Xpot remain unknown. We have performed a combination of classical all-atom and accelerated molecular dynamics simulations on a set of complexes involving Xpot to study a range of features including conformational flexibility of free and cargo-bound Xpot and functionally critical contacts between Xpot and its cargo. The systems investigated include free Xpot and its different complexes, bound either to Ran (GTP/GDP) or tRNA or both. This approach provided a statistically reliable estimate of structural dynamics of Xpot after cargo release. The mechanistic basis for Xpot opening after cargo release has been explained in terms of dynamic structural hinges, about which neighboring region could be displaced to facilitate the nuclear to cytosolic state transition. Post-RanGTP hydrolysis, a cascade of events including local conformational change in RanGTP and loss of critical contacts at Xpot/tRNA interface suggest factors responsible for eventual release of tRNA. The level of flexibility in different Xpot complexes varied depending on the arrangement of individual HEAT repeats. Current study provides one of the most comprehensive and robust analysis carried out on this protein using molecular dynamics schemes.
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Affiliation(s)
- Asmita Gupta
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | | | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India.
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23
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Cretu C, Schmitzová J, Ponce-Salvatierra A, Dybkov O, De Laurentiis EI, Sharma K, Will CL, Urlaub H, Lührmann R, Pena V. Molecular Architecture of SF3b and Structural Consequences of Its Cancer-Related Mutations. Mol Cell 2016; 64:307-319. [PMID: 27720643 DOI: 10.1016/j.molcel.2016.08.036] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/25/2016] [Accepted: 08/30/2016] [Indexed: 11/17/2022]
Abstract
SF3b is a heptameric protein complex of the U2 small nuclear ribonucleoprotein (snRNP) that is essential for pre-mRNA splicing. Mutations in the largest SF3b subunit, SF3B1/SF3b155, are linked to cancer and lead to alternative branch site (BS) selection. Here we report the crystal structure of a human SF3b core complex, revealing how the distinctive conformation of SF3b155's HEAT domain is maintained by multiple contacts with SF3b130, SF3b10, and SF3b14b. Protein-protein crosslinking enabled the localization of the BS-binding proteins p14 and U2AF65 within SF3b155's HEAT-repeat superhelix, which together with SF3b14b forms a composite RNA-binding platform. SF3b155 residues, the mutation of which leads to cancer, contribute to the tertiary structure of the HEAT superhelix and its surface properties in the proximity of p14 and U2AF65. The molecular architecture of SF3b reveals the spatial organization of cancer-related SF3b155 mutations and advances our understanding of their effects on SF3b structure and function.
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Affiliation(s)
- Constantin Cretu
- Research Group Macromolecular Crystallography, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Jana Schmitzová
- Research Group Macromolecular Crystallography, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Almudena Ponce-Salvatierra
- Research Group Macromolecular Crystallography, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Max Planck Research Group Nucleic Acid Chemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Olexandr Dybkov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Evelina I De Laurentiis
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Kundan Sharma
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Bioanalytics Group, Institute for Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Vladimir Pena
- Research Group Macromolecular Crystallography, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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24
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Rakesh R, Joseph AP, Bhaskara RM, Srinivasan N. Structural and mechanistic insights into human splicing factor SF3b complex derived using an integrated approach guided by the cryo-EM density maps. RNA Biol 2016; 13:1025-1040. [PMID: 27618338 DOI: 10.1080/15476286.2016.1218590] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Pre-mRNA splicing in eukaryotes is performed by the spliceosome, a highly complex macromolecular machine. SF3b is a multi-protein complex which recognizes the branch point adenosine of pre-mRNA as part of a larger U2 snRNP or U11/U12 di-snRNP in the dynamic spliceosome machinery. Although a cryo-EM map is available for human SF3b complex, the structure and relative spatial arrangement of all components in the complex are not yet known. We have recognized folds of domains in various proteins in the assembly and generated comparative models. Using an integrative approach involving structural and other experimental data, guided by the available cryo-EM density map, we deciphered a pseudo-atomic model of the closed form of SF3b which is found to be a "fuzzy complex" with highly flexible components and multiplicity of folds. Further, the model provides structural information for 5 proteins (SF3b10, SF3b155, SF3b145, SF3b130 and SF3b14b) and localization information for 4 proteins (SF3b10, SF3b145, SF3b130 and SF3b14b) in the assembly for the first time. Integration of this model with the available U11/U12 di-snRNP cryo-EM map enabled elucidation of an open form. This now provides new insights on the mechanistic features involved in the transition between closed and open forms pivoted by a hinge region in the SF3b155 protein that also harbors cancer causing mutations. Moreover, the open form guided model of the 5' end of U12 snRNA, which includes the branch point duplex, shows that the architecture of SF3b acts as a scaffold for U12 snRNA: pre-mRNA branch point duplex formation with potential implications for branch point adenosine recognition fidelity.
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Affiliation(s)
- Ramachandran Rakesh
- a Molecular Biophysics Unit, Indian Institute of Science , Bangalore , India
| | - Agnel Praveen Joseph
- b National Center for Biological Sciences, TIFR, GKVK Campus , Bangalore , India
| | - Ramachandra M Bhaskara
- a Molecular Biophysics Unit, Indian Institute of Science , Bangalore , India.,b National Center for Biological Sciences, TIFR, GKVK Campus , Bangalore , India
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25
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Alvisi G, Jans DA. Secret life of importin-β; solenoid flexibility as the key to transport through the nuclear pore. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:703-4. [PMID: 27303790 DOI: 10.1107/s2059798316008263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Gualtiero Alvisi
- Department of Molecular Medicine, University of Padua, 35121 Padua, Italy
| | - David A Jans
- Department of Biochemistry and Molecular Biology, Monash University, 3800 Clayton, Victoria, Australia
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26
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Tauchert MJ, Hémonnot C, Neumann P, Köster S, Ficner R, Dickmanns A. Impact of the crystallization condition on importin-β conformation. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:705-17. [DOI: 10.1107/s2059798316004940] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 03/23/2016] [Indexed: 11/10/2022]
Abstract
In eukaryotic cells, the exchange of macromolecules between the nucleus and cytoplasm is highly selective and requires specialized soluble transport factors. Many of them belong to the importin-β superfamily, the members of which share an overall superhelical structure owing to the tandem arrangement of a specific motif, the HEAT repeat. This structural organization leads to great intrinsic flexibility, which in turn is a prerequisite for the interaction with a variety of proteins and for its transport function. During the passage from the aqueous cytosol into the nucleus, the receptor passes the gated channel of the nuclear pore complex filled with a protein meshwork of unknown organization, which seems to be highly selective owing to the presence of FG-repeats, which are peptides with hydrophobic patches. Here, the structural changes of free importin-β from a single organism, crystallized in polar (salt) or apolar (PEG) buffer conditions, are reported. This allowed analysis of the structural changes, which are attributable to the surrounding milieu and are not affected by bound interaction partners. The importin-β structures obtained exhibit significant conformational changes and suggest an influence of the polarity of the environment, resulting in an extended conformation in the PEG condition. The significance of this observation is supported by SAXS experiments and the analysis of other crystal structures of importin-β deposited in the Protein Data Bank.
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27
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Halder K, Dölker N, Van Q, Gregor I, Dickmanns A, Baade I, Kehlenbach RH, Ficner R, Enderlein J, Grubmüller H, Neumann H. MD simulations and FRET reveal an environment-sensitive conformational plasticity of importin-β. Biophys J 2016. [PMID: 26200863 DOI: 10.1016/j.bpj.2015.06.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The nuclear pore complex mediates nucleocytoplasmic transport of macromolecules in eukaryotic cells. Transport through the pore is restricted by a hydrophobic selectivity filter comprising disordered phenylalanine-glycine-rich repeats of nuclear pore proteins. Exchange through the pore requires specialized transport receptors, called exportins and importins, that interact with cargo proteins in a RanGTP-dependent manner. These receptors are highly flexible superhelical structures composed of HEAT-repeat motifs that adopt various degrees of extension in crystal structures. Here, we performed molecular-dynamics simulations using crystal structures of Importin-β in its free form or in complex with nuclear localization signal peptides as the starting conformation. Our simulations predicted that initially compact structures would adopt extended conformations in hydrophilic buffers, while contracted conformations would dominate in more hydrophobic solutions, mimicking the environment of the nuclear pore. We confirmed this experimentally by Förster resonance energy transfer experiments using dual-fluorophore-labeled Importin-β. These observations explain seemingly contradictory crystal structures and suggest a possible mechanism for cargo protection during passage of the nuclear pore. Such hydrophobic switching may be a general principle for environmental control of protein function.
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Affiliation(s)
- Kangkan Halder
- Free Floater (Junior) Research Group "Applied Synthetic Biology", Institute for Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany
| | - Nicole Dölker
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Qui Van
- Third Institute of Physics-Biophysics, Georg-August University Göttingen, Göttingen, Germany
| | - Ingo Gregor
- Third Institute of Physics-Biophysics, Georg-August University Göttingen, Göttingen, Germany
| | - Achim Dickmanns
- Institute for Microbiology and Genetics, Department of Molecular Structural Biology, Georg-August University Göttingen, Göttingen, Germany
| | - Imke Baade
- Department of Molecular Biology, Faculty of Medicine, Georg-August University Göttingen, Göttingen, Germany
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, Georg-August University Göttingen, Göttingen, Germany
| | - Ralf Ficner
- Institute for Microbiology and Genetics, Department of Molecular Structural Biology, Georg-August University Göttingen, Göttingen, Germany
| | - Jörg Enderlein
- Third Institute of Physics-Biophysics, Georg-August University Göttingen, Göttingen, Germany
| | - Helmut Grubmüller
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Heinz Neumann
- Free Floater (Junior) Research Group "Applied Synthetic Biology", Institute for Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany.
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28
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Monecke T, Dickmanns A, Weiss MS, Port SA, Kehlenbach RH, Ficner R. Combining dehydration, construct optimization and improved data collection to solve the crystal structure of a CRM1-RanGTP-SPN1-Nup214 quaternary nuclear export complex. Acta Crystallogr F Struct Biol Commun 2015; 71:1481-7. [PMID: 26625290 PMCID: PMC4666476 DOI: 10.1107/s2053230x15021524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/13/2015] [Indexed: 11/10/2022] Open
Abstract
High conformational flexibility is an intrinsic and indispensable property of nuclear transport receptors, which makes crystallization and structure determination of macromolecular complexes containing exportins or importins particularly challenging. Here, the crystallization and structure determination of a quaternary nuclear export complex consisting of the exportin CRM1, the small GTPase Ran in its GTP-bound form, the export cargo SPN1 and an FG repeat-containing fragment of the nuclear pore complex component nucleoporin Nup214 fused to maltose-binding protein is reported. Optimization of constructs, seeding and the development of a sophisticated protocol including successive PEG-mediated crystal dehydration as well as additional post-mounting steps were essential to obtain well diffracting crystals.
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Affiliation(s)
- Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Manfred S. Weiss
- Macromolecular Crystallography (HZB-MX), Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Sarah A. Port
- Institut für Molekularbiologie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Ralph H. Kehlenbach
- Institut für Molekularbiologie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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29
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Dickmanns A, Monecke T, Ficner R. Structural Basis of Targeting the Exportin CRM1 in Cancer. Cells 2015; 4:538-68. [PMID: 26402707 PMCID: PMC4588050 DOI: 10.3390/cells4030538] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/07/2015] [Accepted: 09/11/2015] [Indexed: 12/19/2022] Open
Abstract
Recent studies have demonstrated the interference of nucleocytoplasmic trafficking with the establishment and maintenance of various cancers. Nucleocytoplasmic transport is highly regulated and coordinated, involving different nuclear transport factors or receptors, importins and exportins, that mediate cargo transport from the cytoplasm into the nucleus or the other way round, respectively. The exportin CRM1 (Chromosome region maintenance 1) exports a plethora of different protein cargoes and ribonucleoprotein complexes. Structural and biochemical analyses have enabled the deduction of individual steps of the CRM1 transport cycle. In addition, CRM1 turned out to be a valid target for anticancer drugs as it exports numerous proto-oncoproteins and tumor suppressors. Clearly, detailed understanding of the flexibility, regulatory features and cooperative binding properties of CRM1 for Ran and cargo is a prerequisite for the design of highly effective drugs. The first compound found to inhibit CRM1-dependent nuclear export was the natural drug Leptomycin B (LMB), which blocks export by competitively interacting with a highly conserved cleft on CRM1 required for nuclear export signal recognition. Clinical studies revealed serious side effects of LMB, leading to a search for alternative natural and synthetic drugs and hence a multitude of novel therapeutics. The present review examines recent progress in understanding the binding mode of natural and synthetic compounds and their inhibitory effects.
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Affiliation(s)
- Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
| | - Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, GZMB, Georg-August-Universität Göttingen, Justus-von-Liebig-Weg 11, Göttingen 37077, Germany.
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Abstract
The human genome encodes seven isoforms of importin α which are grouped into three subfamilies known as α1, α2 and α3. All isoforms share a fundamentally conserved architecture that consists of an N-terminal, autoinhibitory, importin-β-binding (IBB) domain and a C-terminal Arm (Armadillo)-core that associates with nuclear localization signal (NLS) cargoes. Despite striking similarity in amino acid sequence and 3D structure, importin-α isoforms display remarkable substrate specificity in vivo. In the present review, we look at key differences among importin-α isoforms and provide a comprehensive inventory of known viral and cellular cargoes that have been shown to associate preferentially with specific isoforms. We illustrate how the diversification of the adaptor importin α into seven isoforms expands the dynamic range and regulatory control of nucleocytoplasmic transport, offering unexpected opportunities for pharmacological intervention. The emerging view of importin α is that of a key signalling molecule, with isoforms that confer preferential nuclear entry and spatiotemporal specificity on viral and cellular cargoes directly linked to human diseases.
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Molecular determinants for nuclear import of influenza A PB2 by importin α isoforms 3 and 7. Structure 2015; 23:374-84. [PMID: 25599645 DOI: 10.1016/j.str.2014.11.015] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/14/2014] [Accepted: 11/18/2014] [Indexed: 11/23/2022]
Abstract
Influenza A virus polymerase subunit PB2 is a major virulence determinant implicated in pathogenicity and host adaptation. During cross-species virus transfer from avian to mammalian cells, PB2 switches specificity from importin α3 to α7. This specificity is not recapitulated in vitro, where PB2 binds all importin α isoforms with comparably high affinity. In this study, we investigated the structure, conformational dynamics, and autoinhibition of importin α isoforms 1, 3, and 7 in complex with PB2. Our data suggest that association of PB2 with α3 and α7 is favored by reduced autoinhibition of these isoforms and by the unique structure of the nuclear localization signal (NLS) domain of PB2. We propose that by recruiting importin α3 or α7 in the absence of importin β, PB2 reduces the complexity of adaptor-mediated import to a pseudo-bimolecular reaction, thereby acquiring a kinetic advantage over classical NLS cargos, which form an import complex only when importin α and β are simultaneously available.
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Monecke T, Dickmanns A, Ficner R. Allosteric control of the exportin CRM1 unraveled by crystal structure analysis. FEBS J 2014; 281:4179-94. [PMID: 24823279 PMCID: PMC4231977 DOI: 10.1111/febs.12842] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 01/07/2023]
Abstract
Nucleocytoplasmic trafficking in eukaryotic cells is a highly regulated and coordinated process which involves an increasing variety of soluble nuclear transport receptors. Generally, transport receptors specifically bind their cargo and facilitate its transition through nuclear pore complexes, aqueous channels connecting the two compartments. Directionality of such transport events by receptors of the importin β superfamily requires the interaction with the small GTPase Ras-related nuclear antigen (Ran). While importins need RanGTP to release their cargo in the nucleus and thus to terminate import, exportins recruit cargo in the RanGTP-bound state. The exportin chromosome region maintenance 1 (CRM1) is a highly versatile transport receptor that exports a plethora of different protein and RNP cargoes. Moreover, binding of RanGTP and of cargo to CRM1 are highly cooperative events despite the fact that cargo and RanGTP do not interact directly in crystal structures of assembled export complexes. Integrative approaches have recently unraveled the individual steps of the CRM1 transport cycle at a structural level and explained how the HEAT-repeat architecture of CRM1 provides a framework for the key elements to mediate allosteric interactions with RanGTP, Ran binding proteins and cargo. Moreover, during the last decade, CRM1 has become a more and more appreciated target for anti-cancer drugs. Hence, detailed understanding of the flexibility, the regulatory features and the positive binding cooperativity between CRM1, Ran and cargo is a prerequisite for the development of highly effective drugs. Here we review recent structural advances in the characterization of CRM1 and CRM1-containing complexes with a special emphasis on X-ray crystallographic studies.
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Affiliation(s)
- Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, Germany
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Dian C, Bernaudat F, Langer K, Oliva MF, Fornerod M, Schoehn G, Müller CW, Petosa C. Structure of a truncation mutant of the nuclear export factor CRM1 provides insights into the auto-inhibitory role of its C-terminal helix. Structure 2013; 21:1338-49. [PMID: 23850454 DOI: 10.1016/j.str.2013.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 11/23/2022]
Abstract
Chromosome region maintenance 1/exportin1/Xpo1 (CRM1) associates with the GTPase Ran to mediate the nuclear export of proteins bearing a leucine-rich nuclear export signal (NES). CRM1 consists of helical hairpin HEAT repeats and a C-terminal helical extension (C-extension) that inhibits the binding of NES-bearing cargos. We report the crystal structure and small-angle X-ray scattering analysis of a human CRM1 mutant with enhanced NES-binding activity due to deletion of the C-extension. We show that loss of the C-extension leads to a repositioning of CRM1's C-terminal repeats and to a more extended overall conformation. Normal mode analysis predicts reduced rigidity for the deletion mutant, consistent with an observed decrease in thermal stability. Point mutations that destabilize the C-extension shift CRM1 to the more extended conformation, reduce thermal stability, and enhance NES-binding activity. These findings suggest that an important mechanism by which the C-extension regulates CRM1's cargo-binding affinity is by modulating the conformation and flexibility of its HEAT repeats.
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Affiliation(s)
- Cyril Dian
- Université de Grenoble Alpes, Institut de Biologie Structurale, 38027 Grenoble, France
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34
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Taltynov O, Demeulemeester J, Christ F, De Houwer S, Tsirkone VG, Gerard M, Weeks SD, Strelkov SV, Debyser Z. Interaction of transportin-SR2 with Ras-related nuclear protein (Ran) GTPase. J Biol Chem 2013; 288:25603-25613. [PMID: 23878195 DOI: 10.1074/jbc.m113.484345] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) and other lentiviruses are capable of infecting non-dividing cells and, therefore, need to be imported into the nucleus before integration into the host cell chromatin. Transportin-SR2 (TRN-SR2, Transportin-3, TNPO3) is a cellular karyopherin implicated in nuclear import of HIV-1. A model in which TRN-SR2 imports the viral preintegration complex into the nucleus is supported by direct interaction between TRN-SR2 and HIV-1 integrase (IN). Residues in the C-terminal domain of HIV-1 IN that mediate binding to TRN-SR2 were recently delineated. As for most nuclear import cargoes, the driving force behind HIV-1 preintegration complex import is likely a gradient of the GDP- and GTP-bound forms of Ran, a small GTPase. In this study we offer biochemical and structural characterization of the interaction between TRN-SR2 and Ran. By size exclusion chromatography we demonstrate stable complex formation of TRN-SR2 and RanGTP in solution. Consistent with the behavior of normal nuclear import cargoes, HIV-1 IN is released from the complex with TRN-SR2 by RanGTP. Although in concentrated solutions TRN-SR2 by itself was predominantly present as a dimer, the TRN-SR2-RanGTP complex was significantly more compact. Further analysis supported a model wherein one monomer of TRN-SR2 is bound to one monomer of RanGTP. Finally, we present a homology model of the TRN-SR2-RanGTP complex that is in excellent agreement with the experimental small angle x-ray scattering data.
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Affiliation(s)
- Oliver Taltynov
- From the Laboratory for Molecular Virology and Gene Therapy and
| | | | - Frauke Christ
- From the Laboratory for Molecular Virology and Gene Therapy and
| | | | - Vicky G Tsirkone
- Laboratory for Biocrystallography, KU Leuven, B-3000 Leuven, Belgium
| | - Melanie Gerard
- From the Laboratory for Molecular Virology and Gene Therapy and
| | - Stephen D Weeks
- Laboratory for Biocrystallography, KU Leuven, B-3000 Leuven, Belgium
| | - Sergei V Strelkov
- Laboratory for Biocrystallography, KU Leuven, B-3000 Leuven, Belgium
| | - Zeger Debyser
- From the Laboratory for Molecular Virology and Gene Therapy and.
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35
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Monecke T, Haselbach D, Voß B, Russek A, Neumann P, Thomson E, Hurt E, Zachariae U, Stark H, Grubmüller H, Dickmanns A, Ficner R. Structural basis for cooperativity of CRM1 export complex formation. Proc Natl Acad Sci U S A 2013; 110:960-5. [PMID: 23277578 PMCID: PMC3549083 DOI: 10.1073/pnas.1215214110] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In eukaryotes, the nucleocytoplasmic transport of macromolecules is mainly mediated by soluble nuclear transport receptors of the karyopherin-β superfamily termed importins and exportins. The highly versatile exportin chromosome region maintenance 1 (CRM1) is essential for nuclear depletion of numerous structurally and functionally unrelated protein and ribonucleoprotein cargoes. CRM1 has been shown to adopt a toroidal structure in several functional transport complexes and was thought to maintain this conformation throughout the entire nucleocytoplasmic transport cycle. We solved crystal structures of free CRM1 from the thermophilic eukaryote Chaetomium thermophilum. Surprisingly, unbound CRM1 exhibits an overall extended and pitched superhelical conformation. The two regulatory regions, namely the acidic loop and the C-terminal α-helix, are dramatically repositioned in free CRM1 in comparison with the ternary CRM1-Ran-Snurportin1 export complex. Single-particle EM analysis demonstrates that, in a noncrystalline environment, free CRM1 exists in equilibrium between extended, superhelical and compact, ring-like conformations. Molecular dynamics simulations show that the C-terminal helix plays an important role in regulating the transition from an extended to a compact conformation and reveal how the binding site for nuclear export signals of cargoes is modulated by different CRM1 conformations. Combining these results, we propose a model for the cooperativity of CRM1 export complex assembly involving the long-range allosteric communication between the distant binding sites of GTP-bound Ran and cargo.
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MESH Headings
- Active Transport, Cell Nucleus
- Allosteric Regulation
- Amino Acid Sequence
- Binding Sites
- Chaetomium/chemistry
- Chaetomium/genetics
- Chaetomium/metabolism
- Crystallography, X-Ray
- Fungal Proteins/chemistry
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Fungal Proteins/ultrastructure
- Karyopherins/chemistry
- Karyopherins/genetics
- Karyopherins/metabolism
- Karyopherins/ultrastructure
- Microscopy, Electron
- Models, Biological
- Models, Molecular
- Molecular Dynamics Simulation
- Molecular Sequence Data
- Multiprotein Complexes/chemistry
- Multiprotein Complexes/metabolism
- Protein Conformation
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Cytoplasmic and Nuclear/ultrastructure
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Recombinant Fusion Proteins/ultrastructure
- Sequence Homology, Amino Acid
- Static Electricity
- Exportin 1 Protein
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Affiliation(s)
- Thomas Monecke
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - David Haselbach
- Dreidimensionale Kryo-Elektronenmikroskopie, Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Béla Voß
- Abteilung für Theoretische und Computergestützte Biophysik, Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Andreas Russek
- Abteilung für Theoretische und Computergestützte Biophysik, Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Piotr Neumann
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Emma Thomson
- Biochemie-Zentrum der Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Ed Hurt
- Biochemie-Zentrum der Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Ulrich Zachariae
- Scottish Universities' Physics Alliance, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom; and
| | - Holger Stark
- Dreidimensionale Kryo-Elektronenmikroskopie, Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
- Abteilung für Molekulare Kryo-Elektronenmikroskopie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Helmut Grubmüller
- Abteilung für Theoretische und Computergestützte Biophysik, Max-Planck-Institut für Biophysikalische Chemie, D-37077 Göttingen, Germany
| | - Achim Dickmanns
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
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36
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Kappel C, Dölker N, Kumar R, Zink M, Zachariae U, Grubmüller H. Universal relaxation governs the nonequilibrium elasticity of biomolecules. PHYSICAL REVIEW LETTERS 2012; 109:118304. [PMID: 23005687 DOI: 10.1103/physrevlett.109.118304] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 02/26/2012] [Indexed: 06/01/2023]
Abstract
Experimental and computational dynamic force spectroscopy is widely used to determine the mechanical properties of single biomolecules. Whereas so far the focus has mainly been on rupture or unfolding forces, recent force-probe molecular dynamics simulations have revealed a strong loading rate dependence of biomolecular elasticities, which cannot be explained by the established one-dimensional transition-state treatments. We show that this nonequilibrium behavior can be explained by a theory that includes relaxation effects. For three structurally and mechanically quite diverse systems, a single relaxation mode suffices to quantitatively describe their loading-rate-dependent elastic behavior. Atomistic simulations of these systems revealed the microscopic nature of the respective relaxation modes. This result suggests a new type of "elasticity spectroscopy" experiment, which should render nonequilibrium properties of structured macromolecules accessible to single-molecule force spectroscopy.
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Affiliation(s)
- Christian Kappel
- Theoretical & Computational Biophysics, MPI for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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37
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38
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Zhong Y, Wang Y, Yang H, Ballar P, Lee JG, Ye Y, Monteiro MJ, Fang S. Importin beta interacts with the endoplasmic reticulum-associated degradation machinery and promotes ubiquitination and degradation of mutant alpha1-antitrypsin. J Biol Chem 2011; 286:33921-30. [PMID: 21832065 DOI: 10.1074/jbc.m111.272906] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The mechanism by which misfolded proteins in the endoplasmic reticulum (ER) are retrotranslocated to the cytosol for proteasomal degradation is still poorly understood. Here, we show that importin β, a well established nucleocytoplasmic transport protein, interacts with components of the retrotranslocation complex and promotes ER-associated degradation (ERAD). Knockdown of importin β specifically inhibited the degradation of misfolded ERAD substrates but did not affect turnover of non-ERAD proteasome substrates. Genetic studies and in vitro reconstitution assays demonstrate that importin β is critically required for ubiquitination of mutant α1-antitrypsin, a luminal ERAD substrate. Furthermore, we show that importin β cooperates with Ran GTPase to promote ubiquitination and proteasomal degradation of mutant α1-antitrypsin. These results establish an unanticipated role for importin β in ER protein quality control.
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Affiliation(s)
- Yongwang Zhong
- Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, Maryland 21201, USA
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39
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Kaláb P, Solc P, Motlík J. The role of RanGTP gradient in vertebrate oocyte maturation. Results Probl Cell Differ 2011; 53:235-67. [PMID: 21630149 DOI: 10.1007/978-3-642-19065-0_12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The maturation of vertebrate oocyte into haploid gamete, the egg, consists of two specialized asymmetric cell divisions with no intervening S-phase. Ran GTPase has an essential role in relaying the active role of chromosomes in their own segregation by the meiotic process. In addition to its conserved role as a key regulator of macromolecular transport between nucleus and cytoplasm, Ran has important functions during cell division, including in mitotic spindle assembly and in the assembly of nuclear envelope at the exit from mitosis. The cellular functions of Ran are mediated by RanGTP interactions with nuclear transport receptors (NTRs) related to importin β and depend on the existence of chromosome-centered RanGTP gradient. Live imaging with FRET biosensors indeed revealed the existence of RanGTP gradient throughout mouse oocyte maturation. NTR-dependent transport of cell cycle regulators including cyclin B1, Wee2, and Cdc25B between the oocyte cytoplasm and germinal vesicle (GV) is required for normal resumption of meiosis. After GVBD in mouse oocytes, RanGTP gradient is required for timely meiosis I (MI) spindle assembly and provides long-range signal directing egg cortex differentiation. However, RanGTP gradient is not required for MI spindle migration and may be dispensable for MI spindle function in chromosome segregation. In contrast, MII spindle assembly and function in maturing mouse and Xenopus laevis eggs depend on RanGTP gradient, similar to X. laevis MII-derived egg extracts.
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Affiliation(s)
- Petr Kaláb
- Laboratory of Cellular and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892-4256, USA.
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40
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Jamali T, Jamali Y, Mehrbod M, Mofrad MRK. Nuclear pore complex: biochemistry and biophysics of nucleocytoplasmic transport in health and disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 287:233-86. [PMID: 21414590 DOI: 10.1016/b978-0-12-386043-9.00006-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Nuclear pore complexes (NPCs) are the gateways connecting the nucleoplasm and cytoplasm. This structures are composed of over 30 different proteins and 60-125 MDa of mass depending on type of species. NPCs are bilateral pathways that selectively control the passage of macromolecules into and out of the nucleus. Molecules smaller than 40 kDa diffuse through the NPC passively while larger molecules require facilitated transport provided by their attachment to karyopherins. Kinetic studies have shown that approximately 1000 translocations occur per second per NPC. Maintaining its high selectivity while allowing for rapid translocation makes the NPC an efficient chemical nanomachine. In this review, we approach the NPC function via a structural viewpoint. Putting together different pieces of this puzzle, this chapter confers an overall insight into what molecular processes are engaged in import/export of active cargos across the NPC and how different transporters regulate nucleocytoplasmic transport. In the end, the correlation of several diseases and disorders with the NPC structural defects and dysfunctions is discussed.
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Affiliation(s)
- T Jamali
- Department of Bioengineering, University of California, Berkeley, California, USA
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41
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Lott K, Cingolani G. The importin β binding domain as a master regulator of nucleocytoplasmic transport. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:1578-92. [PMID: 21029753 DOI: 10.1016/j.bbamcr.2010.10.012] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 10/11/2010] [Accepted: 10/19/2010] [Indexed: 12/16/2022]
Abstract
Specific and efficient recognition of import cargoes is essential to ensure nucleocytoplasmic transport. To this end, the prototypical karyopherin importin β associates with import cargoes directly or, more commonly, through import adaptors, such as importin α and snurportin. Adaptor proteins bind the nuclear localization sequence (NLS) of import cargoes while recruiting importin β via an N-terminal importin β binding (IBB) domain. The use of adaptors greatly expands and amplifies the repertoire of cellular cargoes that importin β can efficiently import into the cell nucleus and allows for fine regulation of nuclear import. Accordingly, the IBB domain is a dedicated NLS, unique to adaptor proteins that functions as a molecular liaison between importin β and import cargoes. This review provides an overview of the molecular role played by the IBB domain in orchestrating nucleocytoplasmic transport. Recent work has determined that the IBB domain has specialized functions at every step of the import and export pathway. Unexpectedly, this stretch of ~40 amino acids plays an essential role in regulating processes such as formation of the import complex, docking and translocation through the nuclear pore complex (NPC), release of import cargoes into the cell nucleus and finally recycling of import adaptors and importin β into the cytoplasm. Thus, the IBB domain is a master regulator of nucleocytoplasmic transport, whose complex molecular function is only recently beginning to emerge. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.
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Affiliation(s)
- Kaylen Lott
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, USA
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42
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Kappel C, Zachariae U, Dölker N, Grubmüller H. An unusual hydrophobic core confers extreme flexibility to HEAT repeat proteins. Biophys J 2010; 99:1596-603. [PMID: 20816072 PMCID: PMC2931736 DOI: 10.1016/j.bpj.2010.06.032] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 05/10/2010] [Accepted: 06/07/2010] [Indexed: 01/16/2023] Open
Abstract
Alpha-solenoid proteins are suggested to constitute highly flexible macromolecules, whose structural variability and large surface area is instrumental in many important protein-protein binding processes. By equilibrium and nonequilibrium molecular dynamics simulations, we show that importin-beta, an archetypical alpha-solenoid, displays unprecedentedly large and fully reversible elasticity. Our stretching molecular dynamics simulations reveal full elasticity over up to twofold end-to-end extensions compared to its bound state. Despite the absence of any long-range intramolecular contacts, the protein can return to its equilibrium structure to within 3 A backbone RMSD after the release of mechanical stress. We find that this extreme degree of flexibility is based on an unusually flexible hydrophobic core that differs substantially from that of structurally similar but more rigid globular proteins. In that respect, the core of importin-beta resembles molten globules. The elastic behavior is dominated by nonpolar interactions between HEAT repeats, combined with conformational entropic effects. Our results suggest that alpha-solenoid structures such as importin-beta may bridge the molecular gap between completely structured and intrinsically disordered proteins.
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Affiliation(s)
| | | | | | - Helmut Grubmüller
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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43
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Forwood JK, Lange A, Zachariae U, Marfori M, Preast C, Grubmüller H, Stewart M, Corbett AH, Kobe B. Quantitative Structural Analysis of Importin-β Flexibility: Paradigm for Solenoid Protein Structures. Structure 2010; 18:1171-83. [DOI: 10.1016/j.str.2010.06.015] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 05/04/2010] [Accepted: 06/01/2010] [Indexed: 12/24/2022]
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44
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Lott K, Bhardwaj A, Mitrousis G, Pante N, Cingolani G. The importin beta binding domain modulates the avidity of importin beta for the nuclear pore complex. J Biol Chem 2010; 285:13769-80. [PMID: 20197273 DOI: 10.1074/jbc.m109.095760] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Importin beta mediates active passage of cellular substrates through the nuclear pore complex (NPC). Adaptors such as importin alpha and snurportin associate with importin beta via an importin beta binding (IBB) domain. The intrinsic structural flexibility of importin beta allows its concerted interactions with IBB domains, phenylalanine-glycine nucleoporins, and the GTPase Ran during transport. In this paper, we provide evidence that the nature of the IBB domain modulates the affinity of the import complex for the NPC. In permeabilized cells, importin beta imports a cargo fused to the snurportin IBB (sIBB) with approximately 70% reduced energy requirement as compared with the classical importin alpha IBB. At the molecular level, this is explained by approximately 200-fold reduced affinity of importin beta for Nup62, when bound to the sIBB. Consistently, in vivo, the importin beta.sIBB complex has greatly reduced persistence inside the central channel of the NPC. We propose that by controlling the degree of strain in the tertiary structure of importin beta, the IBB domain modulates the affinity of the import complex for nucleoporins, thus dictating its persistence inside the NPC.
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Affiliation(s)
- Kaylen Lott
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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45
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Lee EH, Hsin J, Sotomayor M, Comellas G, Schulten K. Discovery through the computational microscope. Structure 2010; 17:1295-306. [PMID: 19836330 DOI: 10.1016/j.str.2009.09.001] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/01/2009] [Accepted: 09/03/2009] [Indexed: 11/17/2022]
Abstract
All-atom molecular dynamics simulations have become increasingly popular as a tool to investigate protein function and dynamics. However, researchers are concerned about the short time scales covered by simulations, the apparent impossibility to model large and integral biomolecular systems, and the actual predictive power of the molecular dynamics methodology. Here we review simulations that were in the past both hotly disputed and considered key successes, namely of proteins with mainly mechanical functions (titin, fibrinogen, ankyrin, and cadherin). The simulation work covered shows how state-of-the-art modeling alleviates some of the prior concerns and how unrefuted discoveries are made through the "computational microscope."
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Affiliation(s)
- Eric H Lee
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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46
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Kennedy SA, Frazier ML, Steiniger M, Mast AM, Marzluff WF, Redinbo MR. Crystal structure of the HEAT domain from the Pre-mRNA processing factor Symplekin. J Mol Biol 2009; 392:115-28. [PMID: 19576221 PMCID: PMC2748850 DOI: 10.1016/j.jmb.2009.06.062] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 06/15/2009] [Accepted: 06/25/2009] [Indexed: 11/20/2022]
Abstract
The majority of eukaryotic pre-mRNAs are processed by 3'-end cleavage and polyadenylation, although in metazoa the replication-dependent histone mRNAs are processed by 3'-end cleavage but not polyadenylation. The macromolecular complex responsible for processing both canonical and histone pre-mRNAs contains the approximately 1160-residue protein Symplekin. Secondary-structural prediction algorithms identified putative HEAT domains in the 300 N-terminal residues of all Symplekins of known sequence. The structure and dynamics of this domain were investigated to begin elucidating the role Symplekin plays in mRNA maturation. The crystal structure of the Drosophila melanogaster Symplekin HEAT domain was determined to 2.4 A resolution with single-wavelength anomalous dispersion phasing methods. The structure exhibits five canonical HEAT repeats along with an extended 31-amino-acid loop (loop 8) between the fourth and fifth repeat that is conserved within closely related Symplekin sequences. Molecular dynamics simulations of this domain show that the presence of loop 8 dampens correlated and anticorrelated motion in the HEAT domain, therefore providing a neutral surface for potential protein-protein interactions. HEAT domains are often employed for such macromolecular contacts. The Symplekin HEAT region not only structurally aligns with several established scaffolding proteins, but also has been reported to contact proteins essential for regulating 3'-end processing. Together, these data support the conclusion that the Symplekin HEAT domain serves as a scaffold for protein-protein interactions essential to the mRNA maturation process.
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Affiliation(s)
- Sarah A. Kennedy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Monica L. Frazier
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Mindy Steiniger
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Ann M. Mast
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - William F. Marzluff
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
| | - Matthew R. Redinbo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 USA
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