1
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Recouvreux P, Pai P, Dunsing V, Torro R, Ludanyi M, Mélénec P, Boughzala M, Bertrand V, Lenne PF. Transfer of polarity information via diffusion of Wnt ligands in C. elegans embryos. Curr Biol 2024; 34:1853-1865.e6. [PMID: 38604167 DOI: 10.1016/j.cub.2024.03.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 10/26/2023] [Accepted: 03/18/2024] [Indexed: 04/13/2024]
Abstract
Different signaling mechanisms concur to ensure robust tissue patterning and cell fate instruction during animal development. Most of these mechanisms rely on signaling proteins that are produced, transported, and detected. The spatiotemporal dynamics of signaling molecules are largely unknown, yet they determine signal activity's spatial range and time frame. Here, we use the Caenorhabditis elegans embryo to study how Wnt ligands, an evolutionarily conserved family of signaling proteins, dynamically organize to establish cell polarity in a developing tissue. We identify how Wnt ligands, produced in the posterior half of the embryos, spread extracellularly to transmit information to distant target cells in the anterior half. With quantitative live imaging and fluorescence correlation spectroscopy, we show that Wnt ligands diffuse through the embryo over a timescale shorter than the cell cycle, in the intercellular space, and outside the tissue below the eggshell. We extracted diffusion coefficients of Wnt ligands and their receptor Frizzled and characterized their co-localization. Integrating our different measurements and observations in a simple computational framework, we show how fast diffusion in the embryo can polarize individual cells through a time integration of the arrival of the ligands at the target cells. The polarity established at the tissue level by a posterior Wnt source can be transferred to the cellular level. Our results support a diffusion-based long-range Wnt signaling, which is consistent with the dynamics of developing processes.
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Affiliation(s)
- Pierre Recouvreux
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France.
| | - Pritha Pai
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Valentin Dunsing
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Rémy Torro
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Monika Ludanyi
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Pauline Mélénec
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Mariem Boughzala
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Vincent Bertrand
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Pierre-François Lenne
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
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2
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Petrich A, Aji AK, Dunsing V, Chiantia S. Benchmarking of novel green fluorescent proteins for the quantification of protein oligomerization in living cells. PLoS One 2023; 18:e0285486. [PMID: 37535571 PMCID: PMC10399874 DOI: 10.1371/journal.pone.0285486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/25/2023] [Indexed: 08/05/2023] Open
Abstract
Protein-protein-interactions play an important role in many cellular functions. Quantitative non-invasive techniques are applied in living cells to evaluate such interactions, thereby providing a broader understanding of complex biological processes. Fluorescence fluctuation spectroscopy describes a group of quantitative microscopy approaches for the characterization of molecular interactions at single cell resolution. Through the obtained molecular brightness, it is possible to determine the oligomeric state of proteins. This is usually achieved by fusing fluorescent proteins (FPs) to the protein of interest. Recently, the number of novel green FPs has increased, with consequent improvements to the quality of fluctuation-based measurements. The photophysical behavior of FPs is influenced by multiple factors (including photobleaching, protonation-induced "blinking" and long-lived dark states). Assessing these factors is critical for selecting the appropriate fluorescent tag for live cell imaging applications. In this work, we focus on novel green FPs that are extensively used in live cell imaging. A systematic performance comparison of several green FPs in living cells under different pH conditions using Number & Brightness (N&B) analysis and scanning fluorescence correlation spectroscopy was performed. Our results show that the new FP Gamillus exhibits higher brightness at the cost of lower photostability and fluorescence probability (pf), especially at lower pH. mGreenLantern, on the other hand, thanks to a very high pf, is best suited for multimerization quantification at neutral pH. At lower pH, mEGFP remains apparently the best choice for multimerization investigation. These guidelines provide the information needed to plan quantitative fluorescence microscopy involving these FPs, both for general imaging or for protein-protein-interactions quantification via fluorescence fluctuation-based methods.
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Affiliation(s)
- Annett Petrich
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Amit Koikkarah Aji
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Valentin Dunsing
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
- Aix-Marseille University, CNRS, UMR 7288, IBDM, Turing Center for Living Systems, Marseille, France
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
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3
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Bulthuis EP, Dieteren CEJ, Bergmans J, Berkhout J, Wagenaars JA, van de Westerlo EMA, Podhumljak E, Hink MA, Hesp LFB, Rosa HS, Malik AN, Lindert MKT, Willems PHGM, Gardeniers HJGE, den Otter WK, Adjobo-Hermans MJW, Koopman WJH. Stress-dependent macromolecular crowding in the mitochondrial matrix. EMBO J 2023; 42:e108533. [PMID: 36825437 PMCID: PMC10068333 DOI: 10.15252/embj.2021108533] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 01/10/2023] [Accepted: 01/19/2023] [Indexed: 02/25/2023] Open
Abstract
Macromolecules of various sizes induce crowding of the cellular environment. This crowding impacts on biochemical reactions by increasing solvent viscosity, decreasing the water-accessible volume and altering protein shape, function, and interactions. Although mitochondria represent highly protein-rich organelles, most of these proteins are somehow immobilized. Therefore, whether the mitochondrial matrix solvent exhibits macromolecular crowding is still unclear. Here, we demonstrate that fluorescent protein fusion peptides (AcGFP1 concatemers) in the mitochondrial matrix of HeLa cells display an elongated molecular structure and that their diffusion constant decreases with increasing molecular weight in a manner typical of macromolecular crowding. Chloramphenicol (CAP) treatment impaired mitochondrial function and reduced the number of cristae without triggering mitochondrial orthodox-to-condensed transition or a mitochondrial unfolded protein response. CAP-treated cells displayed progressive concatemer immobilization with increasing molecular weight and an eightfold matrix viscosity increase, compatible with increased macromolecular crowding. These results establish that the matrix solvent exhibits macromolecular crowding in functional and dysfunctional mitochondria. Therefore, changes in matrix crowding likely affect matrix biochemical reactions in a manner depending on the molecular weight of the involved crowders and reactants.
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Affiliation(s)
- Elianne P Bulthuis
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Cindy E J Dieteren
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands.,Department of Cell Biology and Electron Microscopy Center, Radboudumc, Nijmegen, The Netherlands
| | - Jesper Bergmans
- Department of Pediatrics, Amalia Children's Hospital, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center (Radboudumc), Nijmegen, The Netherlands
| | - Job Berkhout
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Jori A Wagenaars
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Els M A van de Westerlo
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Emina Podhumljak
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Mark A Hink
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Laura F B Hesp
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Hannah S Rosa
- Department of Diabetes, King's College London, London, UK
| | - Afshan N Malik
- Department of Diabetes, King's College London, London, UK
| | - Mariska Kea-Te Lindert
- Department of Cell Biology and Electron Microscopy Center, Radboudumc, Nijmegen, The Netherlands
| | - Peter H G M Willems
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Han J G E Gardeniers
- Mesoscale Chemical Systems, University of Twente, Enschede, The Netherlands.,MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands
| | - Wouter K den Otter
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.,Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente, Enschede, The Netherlands
| | - Merel J W Adjobo-Hermans
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Centre (Radboudumc), Nijmegen, The Netherlands
| | - Werner J H Koopman
- Department of Pediatrics, Amalia Children's Hospital, Radboud Institute for Molecular Life Sciences (RIMLS), Radboud Center for Mitochondrial Medicine (RCMM), Radboud University Medical Center (Radboudumc), Nijmegen, The Netherlands.,Human and Animal Physiology, Wageningen University, Wageningen, The Netherlands
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4
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Zhang K, Huang M, Li A, Wen J, Yan L, Li Y, Guo L, Senthil KS, Zhou Y, Chen G, Liu Y, Zhang X, Yao X, Qin D, Su H. DIAPH3 condensates formed by liquid-liquid phase separation act as a regulatory hub for stress-induced actin cytoskeleton remodeling. Cell Rep 2023; 42:111986. [PMID: 36640348 DOI: 10.1016/j.celrep.2022.111986] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/24/2022] [Accepted: 12/23/2022] [Indexed: 01/11/2023] Open
Abstract
Membraneless condensates, such as stress granules (SGs) and processing bodies (P-bodies), have attracted wide attention due to their unique feature of rapid response to stress without first requiring nuclear feedback. In this study, we identify diaphanous-related formin 3 (DIAPH3), an actin nucleator, as a scaffold protein to initiate liquid-liquid phase separation (LLPS) and form abundant cytosolic phase-separated DIAPH3 granules (D-granules) in mammalian cells such as HeLa, HEK293, and fibroblasts under various stress conditions. Neither mRNAs nor known stress-associated condensate markers, such as G3BP1, G3BP2, and TIA1 for SGs and DCP1A for P-bodies, are detected in D-granules. Using overexpression and knockout of DIAPH3, pharmacological interventions, and optogenetics, we further demonstrate that stress-induced D-granules spatially sequester DIAPH3 within the condensation to inhibit the assembly of actin filaments in filopodia. This study reveals that D-granules formed by LLPS act as a regulatory hub for actin cytoskeletal remodeling in response to stress.
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Affiliation(s)
- Ke Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Miaodan Huang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Ang Li
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Jing Wen
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Lingli Yan
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Yunhao Li
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Liman Guo
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Kumaran Satyanarayanan Senthil
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Yangyang Zhou
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China
| | - Guobing Chen
- Institute of Geriatric Immunology, School of Medicine, Jinan University, Guangzhou, China
| | - Yong Liu
- Laboratory of Neuroscience in Health and Disease Institute, Guangzhou First People's Hospital School of Medicine, South China University of Technology, Guangzhou, China
| | - Xiaofei Zhang
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Xiaoli Yao
- Department of Neurology, National Key Clinical Department and Key Discipline of Neurology, the First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Dajiang Qin
- Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Huanxing Su
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
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5
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Balasubramanian H, Sankaran J, Pandey S, Goh CJH, Wohland T. The dependence of EGFR oligomerization on environment and structure: A camera-based N&B study. Biophys J 2022; 121:4452-4466. [PMID: 36335429 PMCID: PMC9748371 DOI: 10.1016/j.bpj.2022.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Number and brightness (N&B) analysis is a fluorescence spectroscopy technique to quantify oligomerization of the mobile fraction of proteins. Accurate results, however, rely on a good knowledge of nonfluorescent states of the fluorescent labels, especially of fluorescent proteins, which are widely used in biology. Fluorescent proteins have been characterized for confocal, but not camera-based, N&B, which allows, in principle, faster measurements over larger areas. Here, we calibrate camera-based N&B implemented on a total internal reflection fluorescence microscope for various fluorescent proteins by determining their propensity to be fluorescent. We then apply camera-based N&B in live CHO-K1 cells to determine the oligomerization state of the epidermal growth factor receptor (EGFR), a transmembrane receptor tyrosine kinase that is a crucial regulator of cell proliferation and survival with implications in many cancers. EGFR oligomerization in resting cells and its regulation by the plasma membrane microenvironment are still under debate. Therefore, we investigate the effects of extrinsic factors, including membrane organization, cytoskeletal structure, and ligand stimulation, and intrinsic factors, including mutations in various EGFR domains, on the receptor's oligomerization. Our results demonstrate that EGFR oligomerization increases with removal of cholesterol or sphingolipids or the disruption of GM3-EGFR interactions, indicating raft association. However, oligomerization is not significantly influenced by the cytoskeleton. Mutations in either I706/V948 residues or E685/E687/E690 residues in the kinase and juxtamembrane domains, respectively, lead to a decrease in oligomerization, indicating their necessity for EGFR dimerization. Finally, EGFR phosphorylation is oligomerization dependent, involving the extracellular domain (550-580 residues). Coupled with biochemical investigations, camera-based N&B indicates that EGFR oligomerization and phosphorylation are the outcomes of several molecular interactions involving the lipid content and structure of the cell membrane and multiple residues in the kinase, juxtamembrane, and extracellular domains.
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Affiliation(s)
- Harikrushnan Balasubramanian
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Jagadish Sankaran
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shambhavi Pandey
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Corinna Jie Hui Goh
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore
| | - Thorsten Wohland
- Department of Biological Sciences and NUS Centre for Bio-Imaging Sciences, National University of Singapore, Singapore, Singapore; Department of Chemistry, National University of Singapore, Singapore, Singapore.
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6
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Strobl K, Selivanovitch E, Ibáñez-Freire P, Moreno-Madrid F, Schaap IAT, Delgado-Buscalioni R, Douglas T, de Pablo PJ. Electromechanical Photophysics of GFP Packed Inside Viral Protein Cages Probed by Force-Fluorescence Hybrid Single-Molecule Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200059. [PMID: 35718881 PMCID: PMC9528512 DOI: 10.1002/smll.202200059] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 04/29/2022] [Indexed: 06/15/2023]
Abstract
Packing biomolecules inside virus capsids has opened new avenues for the study of molecular function in confined environments. These systems not only mimic the highly crowded conditions in nature, but also allow their manipulation at the nanoscale for technological applications. Here, green fluorescent proteins are packed in virus-like particles derived from P22 bacteriophage procapsids. The authors explore individual virus cages to monitor their emission signal with total internal reflection fluorescence microscopy while simultaneously changing the microenvironment with the stylus of atomic force microscopy. The mechanical and electronic quenching can be decoupled by ≈10% each using insulator and conductive tips, respectively. While with conductive tips the fluorescence quenches and recovers regardless of the structural integrity of the capsid, with the insulator tips quenching only occurs if the green fluorescent proteins remain organized inside the capsid. The electronic quenching is associated with the coupling of the protein fluorescence emission with the tip surface plasmon resonance. In turn, the mechanical quenching is a consequence of the unfolding of the aggregated proteins during the mechanical disruption of the capsid.
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Affiliation(s)
- Klara Strobl
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | | | - Pablo Ibáñez-Freire
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Francisco Moreno-Madrid
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | | | - Rafael Delgado-Buscalioni
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Institute of Condensed Matter Physics (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Trevor Douglas
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Pedro J de Pablo
- Department of Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, 28049, Spain
- Institute of Condensed Matter Physics (IFIMAC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
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7
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Liu QT, Wang Q, Zhang Y, Kliemke V, Liu Q, Chou KC. The nanoscale organization of Nipah virus matrix protein revealed by super-resolution microscopy. Biophys J 2022; 121:2290-2296. [PMID: 35614854 DOI: 10.1016/j.bpj.2022.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 05/08/2022] [Accepted: 05/18/2022] [Indexed: 11/17/2022] Open
Abstract
The matrix proteins (M) of many enveloped RNA viruses mediate virus assembly and budding. However, it remains poorly understood how M is involved in virus budding and how they interact with envelope proteins. Here, we show that the expression level of Nipah (NiV) M in particles produced by the host cells deviates from a Gamma distribution and does not reflect that of the host cells, indicating assembly of the NiV-M in the process. Our data reveal that NiV-M affects the circularity of the particles while the NiV envelope proteins do not. The organization of NiV envelope proteins on the membrane of the particles is similar to those that do not express NiV-M, suggesting that NiV-M does not directly interact with the envelope proteins during assembly and budding.
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Affiliation(s)
- Qian T Liu
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Qian Wang
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Youchang Zhang
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Vicky Kliemke
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Qian Liu
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada.
| | - Keng C Chou
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada; Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
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8
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Jobbins AM, Campagne S, Weinmeister R, Lucas CM, Gosliga AR, Clery A, Chen L, Eperon LP, Hodson MJ, Hudson AJ, Allain FHT, Eperon IC. Exon-independent recruitment of SRSF1 is mediated by U1 snRNP stem-loop 3. EMBO J 2022; 41:e107640. [PMID: 34779515 PMCID: PMC8724738 DOI: 10.15252/embj.2021107640] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 12/11/2022] Open
Abstract
SRSF1 protein and U1 snRNPs are closely connected splicing factors. They both stimulate exon inclusion, SRSF1 by binding to exonic splicing enhancer sequences (ESEs) and U1 snRNPs by binding to the downstream 5' splice site (SS), and both factors affect 5' SS selection. The binding of U1 snRNPs initiates spliceosome assembly, but SR proteins such as SRSF1 can in some cases substitute for it. The mechanistic basis of this relationship is poorly understood. We show here by single-molecule methods that a single molecule of SRSF1 can be recruited by a U1 snRNP. This reaction is independent of exon sequences and separate from the U1-independent process of binding to an ESE. Structural analysis and cross-linking data show that SRSF1 contacts U1 snRNA stem-loop 3, which is required for splicing. We suggest that the recruitment of SRSF1 to a U1 snRNP at a 5'SS is the basis for exon definition by U1 snRNP and might be one of the principal functions of U1 snRNPs in the core reactions of splicing in mammals.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
MRC London Institute of Medical SciencesLondonUK
- Present address:
Institute of Clinical SciencesImperial College LondonLondonUK
| | - Sébastien Campagne
- Institute of BiochemistryETH ZürichSwitzerland
- Present address:
Inserm U1212CNRS UMR5320ARNA LaboratoryBordeaux CedexFrance
| | - Robert Weinmeister
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Alison R Gosliga
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
- Present address:
Institut für Industrielle GenetikAbt.(eilung) SystembiologieUniversität StuttgartStuttgartGermany
| | | | - Li Chen
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Lucy P Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Mark J Hodson
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of ChemistryUniversity of LeicesterLeicesterUK
| | | | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell BiologyUniversity of LeicesterLeicesterUK
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9
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Rauwolf S, Steegmüller T, Schwaminger SP, Berensmeier S. Purification of a peptide tagged protein via an affinity chromatographic process with underivatized silica. Eng Life Sci 2021; 21:549-557. [PMID: 34690628 PMCID: PMC8518568 DOI: 10.1002/elsc.202100019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/06/2021] [Accepted: 05/25/2021] [Indexed: 11/11/2022] Open
Abstract
Silica is widely used for chromatography resins due to its high mechanical strength, column efficiency, easy manufacturing (i.e. controlled size and porosity), and low-cost. Despite these positive attributes to silica, it is currently used as a backbone for chromatographic resins in biotechnological downstream processing. The aim of this study is to show how the octapeptide (RH)4 can be used as peptide tag for high-purity protein purification on bare silica. The tag possesses a high affinity to deprotonated silanol groups because the tag's arginine groups interact with the surface via an ion pairing mechanism. A chromatographic workflow to purify GFP fused with (RH)4 could be implemented. Purities were determined by SDS-PAGE and RP-HPLC. The equilibrium binding capacity of the fusion protein GFP-(RH)4 on silica is 450 mg/g and the dynamic binding capacity around 3 mg/mL. One-step purification from clarified lysate achieved a purity of 93% and a recovery of 94%. Overloading the column enhances the purity to >95%. Static experiments with different buffers showed variability of the method making the system independent from buffer choice. Our designed peptide tag allows bare silica to be utilized in preparative chromatography for downstream bioprocessing; thus, providing a cost saving factor regarding expensive surface functionalization. Underivatized silica in combination with our (RH)4 peptide tag allows the purification of proteins, in all scales, without relying on complex resins.
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Affiliation(s)
- Stefan Rauwolf
- Department of Mechanical EngineeringTechnical University of MunichMunichGermany
| | - Tobias Steegmüller
- Department of Mechanical EngineeringTechnical University of MunichMunichGermany
| | | | - Sonja Berensmeier
- Department of Mechanical EngineeringTechnical University of MunichMunichGermany
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10
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Nederveen-Schippers LM, Pathak P, Keizer-Gunnink I, Westphal AH, van Haastert PJM, Borst JW, Kortholt A, Skakun V. Combined FCS and PCH Analysis to Quantify Protein Dimerization in Living Cells. Int J Mol Sci 2021; 22:ijms22147300. [PMID: 34298920 PMCID: PMC8307594 DOI: 10.3390/ijms22147300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/25/2021] [Accepted: 07/01/2021] [Indexed: 11/29/2022] Open
Abstract
Protein dimerization plays a crucial role in the regulation of numerous biological processes. However, detecting protein dimers in a cellular environment is still a challenge. Here we present a methodology to measure the extent of dimerization of GFP-tagged proteins in living cells, using a combination of fluorescence correlation spectroscopy (FCS) and photon counting histogram (PCH) analysis of single-color fluorescence fluctuation data. We named this analysis method brightness and diffusion global analysis (BDGA) and adapted it for biological purposes. Using cell lysates containing different ratios of GFP and tandem-dimer GFP (diGFP), we show that the average brightness per particle is proportional to the fraction of dimer present. We further adapted this methodology for its application in living cells, and we were able to distinguish GFP, diGFP, as well as ligand-induced dimerization of FKBP12 (FK506 binding protein 12)-GFP. While other analysis methods have only sporadically been used to study dimerization in living cells and may be prone to errors, this paper provides a robust approach for the investigation of any cytosolic protein using single-color fluorescence fluctuation spectroscopy.
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Affiliation(s)
- Laura M. Nederveen-Schippers
- Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands; (L.M.N.-S.); (P.P.); (I.K.-G.); (P.J.M.v.H.)
| | - Pragya Pathak
- Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands; (L.M.N.-S.); (P.P.); (I.K.-G.); (P.J.M.v.H.)
| | - Ineke Keizer-Gunnink
- Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands; (L.M.N.-S.); (P.P.); (I.K.-G.); (P.J.M.v.H.)
| | - Adrie H. Westphal
- Laboratory of Biochemistry, Wageningen University & Research, 6708 WE Wageningen, The Netherlands; (A.H.W.); (J.W.B.)
| | - Peter J. M. van Haastert
- Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands; (L.M.N.-S.); (P.P.); (I.K.-G.); (P.J.M.v.H.)
| | - Jan Willem Borst
- Laboratory of Biochemistry, Wageningen University & Research, 6708 WE Wageningen, The Netherlands; (A.H.W.); (J.W.B.)
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, 9747 AG Groningen, The Netherlands; (L.M.N.-S.); (P.P.); (I.K.-G.); (P.J.M.v.H.)
- Correspondence: (A.K.); (V.S.)
| | - Victor Skakun
- Department of Systems Analysis and Computer Simulation, Belarusian State University, 220030 Minsk, Belarus
- Correspondence: (A.K.); (V.S.)
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11
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Fukushima R, Yamamoto J, Kinjo M. Empirical Bayes method using surrounding pixel information for number and brightness analysis. Biophys J 2021; 120:2156-2171. [PMID: 33812845 PMCID: PMC8390835 DOI: 10.1016/j.bpj.2021.03.033] [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: 08/28/2020] [Revised: 03/13/2021] [Accepted: 03/23/2021] [Indexed: 11/26/2022] Open
Abstract
Number and brightness (N&B) analysis is useful for monitoring the spatial distribution of the concentration and oligomeric state of fluorescently labeled proteins in cells. N&B analysis is based on the statistical analysis of fluorescence images by using the method of moments (MoM). Furthermore, N&B analysis can determine the particle number and particle brightness, which indicate the concentration and oligomeric state, respectively. However, the statistical accuracy and precision are limited in actual experiments with fluorescent proteins, owing to low excitation and the limited number of images. In this study, we applied maximum likelihood (ML) estimation and maximum a posteriori (MAP) estimation coupled with the empirical Bayes (EB) method (referred to as EB-MAP). In EB-MAP, we constructed a simple prior distribution for a pixel to utilize the information of the surrounding pixels. To evaluate the accuracy and precision of our method, we conducted simulations and experiments and compared the results of MoM, ML, and EB-MAP. The results showed that MoM estimated the particle number with many outliers. The outliers hampered the visibility of the spatial distribution and cellular structure. In contrast, EB-MAP suppressed the number of outliers and improved the visibility notably. The precision of EB-MAP was better by an order of magnitude in terms of particle number and 1.5 times better in terms of particle brightness compared with those of MoM. The proposed method (EB-MAP-N&B) is applicable to studies on fluorescence imaging and would aid in accurately recognizing changes in the concentration and oligomeric state in cells. Our results hold significant importance because quantifying the concentration and oligomeric state would contribute to the understanding of dynamic processes in molecular mechanism in cells.
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Affiliation(s)
- Ryosuke Fukushima
- Laboratory of Molecular Cell Dynamics, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Johtaro Yamamoto
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan; Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
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12
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DeVree BT, Steiner LM, Głazowska S, Ruhnow F, Herburger K, Persson S, Mravec J. Current and future advances in fluorescence-based visualization of plant cell wall components and cell wall biosynthetic machineries. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:78. [PMID: 33781321 PMCID: PMC8008654 DOI: 10.1186/s13068-021-01922-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/05/2021] [Indexed: 05/18/2023]
Abstract
Plant cell wall-derived biomass serves as a renewable source of energy and materials with increasing importance. The cell walls are biomacromolecular assemblies defined by a fine arrangement of different classes of polysaccharides, proteoglycans, and aromatic polymers and are one of the most complex structures in Nature. One of the most challenging tasks of cell biology and biomass biotechnology research is to image the structure and organization of this complex matrix, as well as to visualize the compartmentalized, multiplayer biosynthetic machineries that build the elaborate cell wall architecture. Better knowledge of the plant cells, cell walls, and whole tissue is essential for bioengineering efforts and for designing efficient strategies of industrial deconstruction of the cell wall-derived biomass and its saccharification. Cell wall-directed molecular probes and analysis by light microscopy, which is capable of imaging with a high level of specificity, little sample processing, and often in real time, are important tools to understand cell wall assemblies. This review provides a comprehensive overview about the possibilities for fluorescence label-based imaging techniques and a variety of probing methods, discussing both well-established and emerging tools. Examples of applications of these tools are provided. We also list and discuss the advantages and limitations of the methods. Specifically, we elaborate on what are the most important considerations when applying a particular technique for plants, the potential for future development, and how the plant cell wall field might be inspired by advances in the biomedical and general cell biology fields.
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Affiliation(s)
- Brian T DeVree
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Lisa M Steiner
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Sylwia Głazowska
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Felix Ruhnow
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Klaus Herburger
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Staffan Persson
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
- Joint International Research Laboratory of Metabolic and Developmental Sciences, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
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13
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Li F, Du Z, Huang X, Dong C, Ren J. Analyses of p73 Protein Oligomerization and p73-MDM2 Interaction in Single Living Cells Using In Situ Single Molecule Spectroscopy. Anal Chem 2021; 93:886-894. [PMID: 33393764 DOI: 10.1021/acs.analchem.0c03521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein oligomerization and protein-protein interaction are crucial to regulate protein functions and biological processes. p73 protein is a very important transcriptional factor and can promote apoptosis and cell cycle arrest, and its transcriptional activity is regulated by p73 oligomerization and p73-MDM2 interaction. Although extracellular studies on p73 oligomerization and p73-MDM2 interaction have been carried out, it is unclear how p73 oligomerization and p73-MDM2 interaction occur in living cells. In our study, we described an in situ method for studying p73 oligomerization and p73-MDM2 interaction in living cells by combining fluorescence cross-correlation spectroscopy with a fluorescent protein labeling technique. Lentiviral transfection was used to transfect cells with a plasmid for either p73 or MDM2, each fused to a different fluorescent protein. p73 oligomerization was evaluated using brightness per particle, and the p73-MDM2 interaction was quantified using the cross-correlation value. We constructed a series of p73 mutants in three domains (transactivation domain, DNA binding domain, and oligomerization domain) and MDM2 mutants. We systematically studied p73 oligomerization and the effects of p73 oligomerization and the p73 and MDM2 structures on the p73-MDM2 interaction in single living cells. We have found that the p73 protein can form oligomers and that the p73 structure changes in the oligomerization domain significantly influence its oligomerization. p73 oligomerization and the structure changes significantly affect the p73-MDM2 interaction. Furthermore, the effects of inhibitors on p73 oligomerization and p73-MDM2 interaction were studied.
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Affiliation(s)
- Fucai Li
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Zhixue Du
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Xiangyi Huang
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Chaoqing Dong
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Jicun Ren
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
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14
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Fiebig T, Cramer JT, Bethe A, Baruch P, Curth U, Führing JI, Buettner FFR, Vogel U, Schubert M, Fedorov R, Mühlenhoff M. Structural and mechanistic basis of capsule O-acetylation in Neisseria meningitidis serogroup A. Nat Commun 2020; 11:4723. [PMID: 32948778 PMCID: PMC7501274 DOI: 10.1038/s41467-020-18464-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 08/20/2020] [Indexed: 02/08/2023] Open
Abstract
O-Acetylation of the capsular polysaccharide (CPS) of Neisseria meningitidis serogroup A (NmA) is critical for the induction of functional immune responses, making this modification mandatory for CPS-based anti-NmA vaccines. Using comprehensive NMR studies, we demonstrate that O-acetylation stabilizes the labile anomeric phosphodiester-linkages of the NmA-CPS and occurs in position C3 and C4 of the N-acetylmannosamine units due to enzymatic transfer and non-enzymatic ester migration, respectively. To shed light on the enzymatic transfer mechanism, we solved the crystal structure of the capsule O-acetyltransferase CsaC in its apo and acceptor-bound form and of the CsaC-H228A mutant as trapped acetyl-enzyme adduct in complex with CoA. Together with the results of a comprehensive mutagenesis study, the reported structures explain the strict regioselectivity of CsaC and provide insight into the catalytic mechanism, which relies on an unexpected Gln-extension of a classical Ser-His-Asp triad, embedded in an α/β-hydrolase fold.
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Affiliation(s)
- Timm Fiebig
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
| | | | - Andrea Bethe
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Petra Baruch
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Ute Curth
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Jana I Führing
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
- Fraunhofer International Consortium for Anti-Infective Research (iCAIR), Hannover, Germany
| | - Falk F R Buettner
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Ulrich Vogel
- Institute for Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
| | - Mario Schubert
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Roman Fedorov
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Martina Mühlenhoff
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
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15
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Golonka D, Gerken U, Köhler J, Möglich A. The Association Kinetics Encode the Light Dependence of Arabidopsis Phytochrome B Interactions. J Mol Biol 2020; 432:4327-4340. [PMID: 32534065 DOI: 10.1016/j.jmb.2020.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 05/22/2020] [Accepted: 06/01/2020] [Indexed: 01/18/2023]
Abstract
Plant phytochromes enable vital adaptations to red and far-red light. At the molecular level, these responses are mediated by light-regulated interactions between phytochromes and partner proteins, foremost the phytochrome-interacting factors (PIF). Although known for decades, quantitative analyses of these interactions have long been sparse. To address this deficit, we here studied by an integrated fluorescence-spectroscopic approach the equilibrium and kinetics of Arabidopsis thaliana phytochrome B binding to a tetramerized PIF6 variant. Several readouts consistently showed the stringently light-regulated interaction to be little affected by PIF tetramerization. Analysis of the binding kinetics allowed the determination of bimolecular association and unimolecular dissociation rate constants as a function of light. Unexpectedly, the stronger affinity of A. thaliana phytochrome B under red light relative to far-red light is entirely due to accelerated association rather than decelerated dissociation. The association reaction under red light is highly efficient and only 3-fold slower than the diffusion limit. The present findings pertain equally to the analysis of signal transduction in plants and to the biotechnological application of phytochromes.
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Affiliation(s)
- David Golonka
- Lehrstuhl für Biochemie, Photobiochemie, Universität Bayreuth, 95447 Bayreuth, Germany
| | - Uwe Gerken
- Lehrstuhl für Spektroskopie weicher Materie, Universität Bayreuth, 95447 Bayreuth, Germany
| | - Jürgen Köhler
- Lehrstuhl für Spektroskopie weicher Materie, Universität Bayreuth, 95447 Bayreuth, Germany; Bayerisches Polymer Institut, Universität Bayreuth, 95447 Bayreuth, Germany; Bayreuther Institut für Makromolekülforschung, 95447 Bayreuth, Germany.
| | - Andreas Möglich
- Lehrstuhl für Biochemie, Photobiochemie, Universität Bayreuth, 95447 Bayreuth, Germany; Bayreuth Center for Biochemistry & Molecular Biology, Universität Bayreuth, 95447 Bayreuth, Germany; North-Bavarian NMR Center, Universität Bayreuth, 95447 Bayreuth, Germany.
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16
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Boutant E, Bonzi J, Anton H, Nasim MB, Cathagne R, Réal E, Dujardin D, Carl P, Didier P, Paillart JC, Marquet R, Mély Y, de Rocquigny H, Bernacchi S. Zinc Fingers in HIV-1 Gag Precursor Are Not Equivalent for gRNA Recruitment at the Plasma Membrane. Biophys J 2020; 119:419-433. [PMID: 32574557 PMCID: PMC7376094 DOI: 10.1016/j.bpj.2020.05.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/15/2020] [Accepted: 05/06/2020] [Indexed: 01/16/2023] Open
Abstract
The human immunodeficiency virus type 1 Gag precursor specifically selects the unspliced viral genomic RNA (gRNA) from the bulk of cellular and spliced viral RNAs via its nucleocapsid (NC) domain and drives gRNA encapsidation at the plasma membrane (PM). To further identify the determinants governing the intracellular trafficking of Gag-gRNA complexes and their accumulation at the PM, we compared, in living and fixed cells, the interactions between gRNA and wild-type Gag or Gag mutants carrying deletions in NC zinc fingers (ZFs) or a nonmyristoylated version of Gag. Our data showed that the deletion of both ZFs simultaneously or the complete NC domain completely abolished intracytoplasmic Gag-gRNA interactions. Deletion of either ZF delayed the delivery of gRNA to the PM but did not prevent Gag-gRNA interactions in the cytoplasm, indicating that the two ZFs display redundant roles in this respect. However, ZF2 played a more prominent role than ZF1 in the accumulation of the ribonucleoprotein complexes at the PM. Finally, the myristate group, which is mandatory for anchoring the complexes at the PM, was found to be dispensable for the association of Gag with the gRNA in the cytosol.
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Affiliation(s)
- Emmanuel Boutant
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
| | - Jeremy Bonzi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Halina Anton
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Maaz Bin Nasim
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Raphael Cathagne
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Eléonore Réal
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Denis Dujardin
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Philippe Carl
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Pascal Didier
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Jean-Christophe Paillart
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Hugues de Rocquigny
- Morphogenèse et Antigénicité du VIH et des Virus des Hépatites, Inserm - U1259 MAVIVH, Tours, France.
| | - Serena Bernacchi
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR9002, Strasbourg, France.
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17
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Heckmeier PJ, Agam G, Teese MG, Hoyer M, Stehle R, Lamb DC, Langosch D. Determining the Stoichiometry of Small Protein Oligomers Using Steady-State Fluorescence Anisotropy. Biophys J 2020; 119:99-114. [PMID: 32553128 DOI: 10.1016/j.bpj.2020.05.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 04/24/2020] [Accepted: 05/04/2020] [Indexed: 11/19/2022] Open
Abstract
A large fraction of soluble and membrane-bound proteins exists as non-covalent dimers, trimers, and higher-order oligomers. The experimental determination of the oligomeric state or stoichiometry of proteins remains a nontrivial challenge. In one approach, the protein of interest is genetically fused to green fluorescent protein (GFP). If a fusion protein assembles into a non-covalent oligomeric complex, exciting their GFP moiety with polarized fluorescent light elicits homotypic Förster resonance energy transfer (homo-FRET), in which the emitted radiation is partially depolarized. Fluorescence depolarization is associated with a decrease in fluorescence anisotropy that can be exploited to calculate the oligomeric state. In a classical approach, several parameters obtained through time-resolved and steady-state anisotropy measurements are required for determining the stoichiometry of the oligomers. Here, we examined novel approaches in which time-resolved measurements of reference proteins provide the parameters that can be used to interpret the less expensive steady-state anisotropy data of candidates. In one approach, we find that using average homo-FRET rates (kFRET), average fluorescence lifetimes (τ), and average anisotropies of those fluorophores that are indirectly excited by homo-FRET (rET) do not compromise the accuracy of calculated stoichiometries. In the other approach, fractional photobleaching of reference oligomers provides a novel parameter a whose dependence on stoichiometry allows one to quantitatively interpret the increase of fluorescence anisotropy seen after photobleaching the candidates. These methods can at least reliably distinguish monomers from dimers and trimers.
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Affiliation(s)
- Philipp J Heckmeier
- Center for Integrated Protein Science Munich (CIPSM), Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Freising, Germany
| | - Ganesh Agam
- Physical Chemistry, Department of Chemistry, Center for Nano Science (CENS), Center for Integrated Protein Science (CIPSM) and Nanosystems Initiative München (NIM), Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Mark G Teese
- Center for Integrated Protein Science Munich (CIPSM), Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Freising, Germany
| | - Maria Hoyer
- Physical Chemistry, Department of Chemistry, Center for Nano Science (CENS), Center for Integrated Protein Science (CIPSM) and Nanosystems Initiative München (NIM), Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Ralf Stehle
- Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany; Center for Integrated Protein Science Munich (CIPSM), Chair Biomolecular NMR Spectroscopy, Department Chemie, Technische Universität München, Garching, Germany
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nano Science (CENS), Center for Integrated Protein Science (CIPSM) and Nanosystems Initiative München (NIM), Ludwig-Maximilians-Universität Munich, Munich, Germany.
| | - Dieter Langosch
- Center for Integrated Protein Science Munich (CIPSM), Lehrstuhl für Chemie der Biopolymere, Technische Universität München, Freising, Germany.
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18
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Zamora RA, Fuentes-Lemus E, Barrias P, Herrera-Morande A, Mura F, Guixé V, Castro-Fernandez V, Rojas T, López-Alarcón C, Aguirre P, Rivas-Aravena A, Aspée A. Free radicals derived from γ-radiolysis of water and AAPH thermolysis mediate oxidative crosslinking of eGFP involving Tyr-Tyr and Tyr-Cys bonds: the fluorescence of the protein is conserved only towards peroxyl radicals. Free Radic Biol Med 2020; 150:40-52. [PMID: 32081747 DOI: 10.1016/j.freeradbiomed.2020.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/29/2020] [Accepted: 02/08/2020] [Indexed: 10/25/2022]
Abstract
The enhanced green fluorescent protein (eGFP) is one of the most employed variants of fluorescent proteins. Nonetheless little is known about the oxidative modifications that this protein can undergo in the cellular milieu. The present work explored the consequences of the exposure of eGFP to free radicals derived from γ-radiolysis of water, and AAPH thermolysis. Results demonstrated that protein crosslinking was the major pathway of modification of eGFP towards these oxidants. As evidenced by HPLC-FLD and UPLC-MS, eGFP crosslinking would occur as consequence of a mixture of pathways including the recombination of two protein radicals, as well as secondary reactions between nucleophilic residues (e.g. lysine, Lys) with protein carbonyls. The first mechanism was supported by detection of dityrosine and cysteine-tyrosine bonds, whilst evidence of formation of protein carbonyls, along with Lys consumption, would suggest the formation and participation of Schiff bases in the crosslinking process. Despite of the degree of oxidative modifications elicited by peroxyl radicals (ROO•) generated from the thermolysis of AAPH, and free radicals generated from γ-radiolysis of water, that were evidenced at amino acidic level, only the highest dose of γ-irradiation (10 kGy) triggered significant changes in the secondary structure of eGFP. These results were accompanied by the complete loss of fluorescence arising from the chromophore unit of eGFP in γ-irradiation-treated samples, whereas it was conserved in ROO•-treated samples. These data have potential biological significance, as this fluorescent protein is widely employed to study interactions between cytosolic proteins; consequently, the formation of fluorescent eGFP dimers could act as artifacts in such experiments.
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Affiliation(s)
- Ricardo A Zamora
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Eduardo Fuentes-Lemus
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Pablo Barrias
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Alejandra Herrera-Morande
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile; Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Francisco Mura
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Victoria Guixé
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | | | - Tomás Rojas
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile
| | - Camilo López-Alarcón
- Departamento de Química Física, Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paulina Aguirre
- Comisión Chilena de Energía Nuclear, Departamento de Tecnología Nucleares, Nueva Bilbao 12501, Santiago, 7600713, Chile
| | - Andrea Rivas-Aravena
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Lota 2465, Providencia, Santiago, 7510157, Chile.
| | - Alexis Aspée
- Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile.
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19
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Unzueta U, Roldán M, Pesarrodona M, Benitez R, Sánchez-Chardi A, Conchillo-Solé O, Mangues R, Villaverde A, Vázquez E. Self-assembling as regular nanoparticles dramatically minimizes photobleaching of tumour-targeted GFP. Acta Biomater 2020; 103:272-280. [PMID: 31812843 DOI: 10.1016/j.actbio.2019.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 11/29/2019] [Accepted: 12/03/2019] [Indexed: 11/25/2022]
Abstract
Fluorescent proteins are useful imaging and theranostic agents, but their potential superiority over alternative dyes is weakened by substantial photobleaching under irradiation. Enhancing protein photostability has been attempted through diverse strategies, with irregular results and limited applicability. In this context, we wondered if the controlled oligomerization of Green Fluorescent Protein (GFP) as nanoscale supramolecular complexes could stabilize the fluorophore through the newly formed protein-protein contacts, and thus, enhance its global photostability. For that, we have here analyzed the photobleaching profile of several GFP versions, engineered to self-assemble as tumour-homing nanoparticles with different targeting, size and structural stability. This has been done under prolonged irradiation in confocal laser scanning microscopy and by small-angle X-ray scattering. The results show that the oligomerization of GFP at the nanoscale enhances, by more than seven-fold, the stability of fluorescence emission. Interestingly, GFP nanoparticles are much more resistant to X-ray damage than the building block counterparts, indicating that the gained photostability is linked to enhanced structural resistance to radiation. Therefore, the controlled oligomerization of self-assembling fluorescent proteins as protein nanoparticles is a simple, versatile and powerful method to enhance their photostability for uses in precision imaging and therapy. STATEMENT OF SIGNIFICANCE: Fluorescent protein assembly into regular and highly symmetric nanoscale structures has been identified to confer enhanced structural stability against radiation stresses dramatically reducing their photobleaching. Being this the main bottleneck in the use of fluorescent proteins for imaging and theranostics, this protein architecture engineering principle appears as a powerful method to enhance their photostability for a broad applicability in precision imaging, drug delivery and theranostics.
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20
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Kates PA, Tomashek JJ, Miles DA, Lee LA. Parallel sample processing using dispersive INtip micro-purification on programmable multichannel pipettes. Biotechniques 2020; 68:148-154. [PMID: 31939309 DOI: 10.2144/btn-2019-0140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Automation gives researchers the ability to process and screen orders of magnitude higher numbers of samples than manual experimentation. Current biomacromolecule separation methodologies suffer from necessary manual intervention, making their translation to high-throughput automation difficult. Herein, we present the first characterization of biomacromolecule affinity purification via dispersive solid-phase extraction in a pipette tip (INtip). We use commercially available resin and compare efficiency with batch and spin column methodologies. Moreover, we measure the kinetics of binding and evaluate resin binding capacities. INtip technology is effective on, and scalable for, an automated platform (INTEGRA ASSIST). The results suggest that high-throughput biomolecular workflows will benefit from the integration of INtip separations.
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Affiliation(s)
- Patrick A Kates
- Integrated Micro-Chromatography Systems, Inc., Irmo, SC, USA
| | - John J Tomashek
- Integrated Micro-Chromatography Systems, Inc., Irmo, SC, USA
| | - David A Miles
- Integrated Micro-Chromatography Systems, Inc., Irmo, SC, USA
| | - L Andrew Lee
- Integrated Micro-Chromatography Systems, Inc., Irmo, SC, USA
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21
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A toolkit for expression of Strep-tagged enhanced green fluorescent protein concatemers in mammalian cells. Anal Biochem 2019; 586:113430. [PMID: 31521668 DOI: 10.1016/j.ab.2019.113430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 09/11/2019] [Accepted: 09/11/2019] [Indexed: 11/21/2022]
Abstract
Green fluorescent protein (GFP) and its variants are widely used tools in life sciences. Recently, we and others have used enhanced green fluorescent protein (EGFP) concatemers for determination of nuclear localization signal strength, as natural fluorescence standards and for mapping mobility in living cell nuclei. In this study, we present a molecular toolbox of Strep-tagged EGFP concatemers ranging from 1 to 12 subunits (Addgene plasmids #122488-122499). EGFP concatemers can be easily fused to targeting motifs of any origin by oligonucleotide ligation. Subsequently, we used liposomal transfection for transient expression of EGFP concatemers in eukaryotic cells. We have tested multiple protocols for further processing of the cells and recommend use of formalin or paraformaldehyde/methanol fixation. After usage of these protocols, we were able to detect concatemers by both GFP fluorescence microscopy and αStrep immunomicroscopy. In addition, we observed a more reliable detection of the StrepTag polypeptide (SA-WSHPQFEK) when using αStrepTag antibody instead of StrepTag binding protein. Summing up, we present a toolbox for expression of a wide range of Strep-tagged EGFP concatemers for multiple applications. By use of EGFP fluorescence and/or StrepTag polypeptide, the expressed concatemers can be easily detected in the cell.
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22
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Jobbins AM, Reichenbach LF, Lucas CM, Hudson AJ, Burley GA, Eperon IC. The mechanisms of a mammalian splicing enhancer. Nucleic Acids Res 2019; 46:2145-2158. [PMID: 29394380 PMCID: PMC5861446 DOI: 10.1093/nar/gky056] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/19/2018] [Indexed: 12/21/2022] Open
Abstract
Exonic splicing enhancer (ESE) sequences are bound by serine & arginine-rich (SR) proteins, which in turn enhance the recruitment of splicing factors. It was inferred from measurements of splicing around twenty years ago that Drosophila doublesex ESEs are bound stably by SR proteins, and that the bound proteins interact directly but with low probability with their targets. However, it has not been possible with conventional methods to demonstrate whether mammalian ESEs behave likewise. Using single molecule multi-colour colocalization methods to study SRSF1-dependent ESEs, we have found that that the proportion of RNA molecules bound by SRSF1 increases with the number of ESE repeats, but only a single molecule of SRSF1 is bound. We conclude that initial interactions between SRSF1 and an ESE are weak and transient, and that these limit the activity of a mammalian ESE. We tested whether the activation step involves the propagation of proteins along the RNA or direct interactions with 3' splice site components by inserting hexaethylene glycol or abasic RNA between the ESE and the target 3' splice site. These insertions did not block activation, and we conclude that the activation step involves direct interactions. These results support a model in which regulatory proteins bind transiently and in dynamic competition, with the result that each ESE in an exon contributes independently to the probability that an activator protein is bound and in close proximity to a splice site.
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Affiliation(s)
- Andrew M Jobbins
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
| | | | - Christian M Lucas
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
| | - Andrew J Hudson
- Leicester Institute of Structural & Chemical Biology and Department of Chemistry, University of Leicester, UK
| | - Glenn A Burley
- Department of Pure and Applied Chemistry, University of Strathclyde, UK
| | - Ian C Eperon
- Leicester Institute of Structural & Chemical Biology and Department of Molecular & Cell Biology, University of Leicester, UK
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23
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Vallotton P, Rajoo S, Wojtynek M, Onischenko E, Kralt A, Derrer CP, Weis K. Mapping the native organization of the yeast nuclear pore complex using nuclear radial intensity measurements. Proc Natl Acad Sci U S A 2019; 116:14606-14613. [PMID: 31262825 PMCID: PMC6642398 DOI: 10.1073/pnas.1903764116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Selective transport across the nuclear envelope (NE) is mediated by the nuclear pore complex (NPC), a massive ∼100-MDa assembly composed of multiple copies of ∼30 nuclear pore proteins (Nups). Recent advances have shed light on the composition and structure of NPCs, but approaches that could map their organization in live cells are still lacking. Here, we introduce an in vivo method to perform nuclear radial intensity measurements (NuRIM) using fluorescence microscopy to determine the average position of NE-localized proteins along the nucleocytoplasmic transport axis. We apply NuRIM to study the organization of the NPC and the mobile transport machinery in budding yeast. This reveals a unique snapshot of the intact yeast NPC and identifies distinct steady-state localizations for various NE-associated proteins and nuclear transport factors. We find that the NPC architecture is robust against compositional changes and could also confirm that in contrast to Chlamydomonas reinhardtii, the scaffold Y complex is arranged symmetrically in the yeast NPC. Furthermore, NuRIM was applied to probe the orientation of intrinsically disordered FG-repeat segments, providing insight into their roles in selective NPC permeability and structure.
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Affiliation(s)
- Pascal Vallotton
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland;
| | - Sasikumar Rajoo
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland
| | - Matthias Wojtynek
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland
- Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland
| | - Evgeny Onischenko
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland
| | - Annemarie Kralt
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland
| | - Carina Patrizia Derrer
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland
| | - Karsten Weis
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETH Zürich), 8093 Zürich, Switzerland;
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24
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EGF Receptor Stalls upon Activation as Evidenced by Complementary Fluorescence Correlation Spectroscopy and Fluorescence Recovery after Photobleaching Measurements. Int J Mol Sci 2019; 20:ijms20133370. [PMID: 31323980 PMCID: PMC6650801 DOI: 10.3390/ijms20133370] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/04/2019] [Accepted: 07/05/2019] [Indexed: 12/28/2022] Open
Abstract
To elucidate the molecular details of the activation-associated clustering of epidermal growth factor receptors (EGFRs), the time course of the mobility and aggregation states of eGFP tagged EGFR in the membranes of Chinese hamster ovary (CHO) cells was assessed by in situ mobility assays. Fluorescence correlation spectroscopy (FCS) was used to probe molecular movements of small ensembles of molecules over short distances and time scales, and to report on the state of aggregation. The diffusion of larger ensembles of molecules over longer distances (and time scales) was investigated by fluorescence recovery after photobleaching (FRAP). Autocorrelation functions could be best fitted by a two-component diffusion model corrected for triplet formation and blinking. The slow, 100–1000 ms component was attributed to membrane localized receptors moving with free Brownian diffusion, whereas the fast, ms component was assigned to cytosolic receptors or their fragments. Upon stimulation with 50 nM EGF, a significant decrease from 0.11 to 0.07 μm2/s in the diffusion coefficient of membrane-localized receptors was observed, followed by recovery to the original value in ~20 min. In contrast, the apparent brightness of diffusing species remained the same. Stripe FRAP experiments yielded a decrease in long-range molecular mobility directly after stimulation, evidenced by an increase in the recovery time of the slow component from 13 to 21.9 s. Our observations are best explained by the transient attachment of ligand-bound EGFRs to immobile or slowly moving structures such as the cytoskeleton or large, previously photobleached receptor aggregates.
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25
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Aguiño C, Lang M, Fernández-Luna V, Pröschel M, Sonnewald U, Coto PB, Costa RD. Single-Component Biohybrid Light-Emitting Diodes Using a White-Emitting Fused Protein. ACS OMEGA 2018; 3:15829-15836. [PMID: 31458231 PMCID: PMC6644152 DOI: 10.1021/acsomega.8b02226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/24/2018] [Indexed: 05/26/2023]
Abstract
This work presents a pioneering multidisciplinary approach toward enhancing biohybrid light-emitting diodes (BioHLEDs), merging synthetic biology tools, polymer chemistry, and device engineering to design a thin color down-converting coating with a single white-emitting fluorescent protein (WFP). In particular, the WFP consists of fused red-, green-, and blue-emitting FPs following the so-called protein superglue approach. This WFP shows an efficient and stable white emission originated from a Förster resonance energy transfer between FP moieties. The emission chromaticity is, in addition, easily controlled by the rigidity of the polymer matrix of the coating, reaching photoluminescence quantum yields of 26% that stand out among intrinsic white-emitting materials. The WFP single-component color down-converting packaging was applied to fabricate BioHLEDs featuring efficient neutral white emission that is stable over 400 h. This represents the most stable BioHLED reported to date. Thus, this work is a landmark for the use of synthetic biology tools to design tailored luminescent biomaterials for lighting applications.
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Affiliation(s)
- Carmen
F. Aguiño
- IMDEA
Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid, Spain
| | - Martina Lang
- Department
of Biology, University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Germany
| | | | - Marlene Pröschel
- Department
of Biology, University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Uwe Sonnewald
- Department
of Biology, University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Pedro B. Coto
- Department
of Physical and Analytical Chemistry, University
of Oviedo, Avda. Julián Clavería 8, 33006 Oviedo, Spain
| | - Rubén D. Costa
- IMDEA
Materials Institute, Calle Eric Kandel 2, 28906 Getafe, Madrid, Spain
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26
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Monomerization of the photoconvertible fluorescent protein SAASoti by rational mutagenesis of single amino acids. Sci Rep 2018; 8:15542. [PMID: 30341334 PMCID: PMC6195611 DOI: 10.1038/s41598-018-33250-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 09/21/2018] [Indexed: 12/19/2022] Open
Abstract
Photoconvertible fluorescent proteins (PCFPs) are widely used as markers for the visualization of intracellular processes and for sub-diffraction single-molecule localization microscopy. Although wild type of a new photoconvertible fluorescent protein SAASoti tends to aggregate, we succeeded, via rational mutagenesis, to obtain variants that formed either tetramers or monomers. We compare two approaches: one is based on the structural similarity between SAASoti and Kaede, which helped us to identify a single point mutation (V127T) at the protein’s hydrophobic interface that leads to monomerization. The other is based on a chemical modification of amino groups of SAASoti with succinic anhydride, which converts the protein aggregates into monomers. Mass-spectrometric analysis helped us to identify that the modification of a single ε-amino group of lysine K145 in the strongly charged interface AB was sufficient to convert the protein into its tetrameric form. Furthermore, site-directed mutagenesis was used to generate mutants that proved to be either monomeric or tetrameric, both capable of rapid green-to-red photoconversion. This allows SAASoti to be used as a photoconvertible fluorescent marker for in vivo cell studies.
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27
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Li Y, Shivnaraine RV, Huang F, Wells JW, Gradinaru CC. Ligand-Induced Coupling between Oligomers of the M 2 Receptor and the G i1 Protein in Live Cells. Biophys J 2018; 115:881-895. [PMID: 30131171 DOI: 10.1016/j.bpj.2018.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/23/2018] [Accepted: 08/02/2018] [Indexed: 02/07/2023] Open
Abstract
Uncertainty over the mechanism of signaling via G protein-coupled receptors (GPCRs) relates in part to questions regarding their supramolecular structure. GPCRs and heterotrimeric G proteins are known to couple as monomers under various conditions. Many GPCRs form oligomers under many of the same conditions, however, and the biological role of those complexes is unclear. We have used dual-color fluorescence correlation spectroscopy to identify oligomers of the M2 muscarinic receptor and of Gi1 in purified preparations and live Chinese hamster ovary cells. Measurements on differently tagged receptors (i.e., eGFP-M2 and mCherry-M2) and G proteins (i.e., eGFP-Gαi1β1γ2 and mCherry-Gαi1β1γ2) detected significant cross-correlations between the two fluorophores in each case, both in detergent micelles and in live cells, indicating that both the receptor and Gi1 can exist as homo-oligomers. Oligomerization of differently tagged Gi1 decreased upon the activation of co-expressed wild-type M2 receptor by an agonist. Measurements on a tagged M2 receptor (M2-mCherry) and eGFP-Gαi1β1γ2 co-expressed in live cells detected cross-correlations only in the presence of an agonist, which therefore promoted coupling of the receptor and the G protein. The effect of the agonist was retained when a fluorophore-tagged receptor lacking the orthosteric site (i.e., M2(D103A)-mCherry) was co-expressed with the wild-type receptor and eGFP-Gαi1β1γ2, indicating that the ligand acted via an oligomeric receptor. Our results point to a model in which an agonist promotes transient coupling of otherwise independent oligomers of the M2 receptor on the one hand and of Gi1 on the other and that an activated complex leads to a reduction in the oligomeric size of the G protein. They suggest that GPCR-mediated signaling proceeds, at least in part, via oligomers.
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Affiliation(s)
- Yuchong Li
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Rabindra V Shivnaraine
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Fei Huang
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Claudiu C Gradinaru
- Department of Physics, University of Toronto, Toronto, Ontario, Canada; Department of Chemical & Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, Canada.
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28
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Dunsing V, Luckner M, Zühlke B, Petazzi RA, Herrmann A, Chiantia S. Optimal fluorescent protein tags for quantifying protein oligomerization in living cells. Sci Rep 2018; 8:10634. [PMID: 30006597 PMCID: PMC6045628 DOI: 10.1038/s41598-018-28858-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/02/2018] [Indexed: 11/30/2022] Open
Abstract
Fluorescence fluctuation spectroscopy has become a popular toolbox for non-disruptive analysis of molecular interactions in living cells. The quantification of protein oligomerization in the native cellular environment is highly relevant for a detailed understanding of complex biological processes. An important parameter in this context is the molecular brightness, which serves as a direct measure of oligomerization and can be easily extracted from temporal or spatial fluorescence fluctuations. However, fluorescent proteins (FPs) typically used in such studies suffer from complex photophysical transitions and limited maturation, inducing non-fluorescent states. Here, we show how these processes strongly affect molecular brightness measurements. We perform a systematic characterization of non-fluorescent states for commonly used FPs and provide a simple guideline for accurate, unbiased oligomerization measurements in living cells. Further, we focus on novel red FPs and demonstrate that mCherry2, an mCherry variant, possesses superior properties with regards to precise quantification of oligomerization.
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Affiliation(s)
- Valentin Dunsing
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Madlen Luckner
- Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Boris Zühlke
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Roberto A Petazzi
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Andreas Herrmann
- Institute for Biology, IRI Life Sciences, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Salvatore Chiantia
- Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
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29
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Ali R, Ramadurai S, Barry F, Nasheuer HP. Optimizing fluorescent protein expression for quantitative fluorescence microscopy and spectroscopy using herpes simplex thymidine kinase promoter sequences. FEBS Open Bio 2018; 8:1043-1060. [PMID: 29928582 PMCID: PMC5985997 DOI: 10.1002/2211-5463.12432] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 03/19/2018] [Accepted: 04/10/2018] [Indexed: 12/22/2022] Open
Abstract
The modulation of expression levels of fluorescent fusion proteins (FFPs) is central for recombinant DNA technologies in modern biology as overexpression of proteins contributes to artifacts in biological experiments. In addition, some microscopy techniques such as fluorescence correlation spectroscopy (FCS) and single-molecule-based techniques are very sensitive to high expression levels of FFPs. To reduce the levels of recombinant protein expression in comparison with the commonly used, very strong CMV promoter, the herpes simplex virus thymidine kinase (TK) gene promoter, and mutants thereof were analyzed. Deletion mutants of the TK promoter were constructed and introduced into the Gateway® system for ectopic expression of enhanced green fluorescent protein (eGFP), monomeric cherry (mCherry), and FFPs containing these FPs. Two promoter constructs, TK2ST and TKTSC, were established, which have optimal low expression levels suitable for FCS studies in U2OS, HeLa CCL2, NIH 3T3, and BALB/c cells. Interestingly, when tested in these four cell lines, promoter constructs having a deletion within TK gene 5'-UTR showed significantly higher protein expression levels than the equivalent constructs lacking this deletion. This suggests that a negative regulatory element is localized within the TK gene 5'-UTR.
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Affiliation(s)
- Rizwan Ali
- Systems Biology IrelandNUI GalwayIreland
- BiochemistrySchool of Natural Sciences and Centre for Chromosome BiologyNational University of Ireland GalwayIreland
- Present address:
Medical Core Facility & Research PlatformsKing Abdullah International Medical Research CenterNational Guard Health AffairsP.O. Box 3660Riyadh11481 Mail Code 1515Saudi Arabia
| | - Sivaramakrishnan Ramadurai
- Systems Biology IrelandNUI GalwayIreland
- BiochemistrySchool of Natural Sciences and Centre for Chromosome BiologyNational University of Ireland GalwayIreland
- Present address:
School of Chemical SciencesDublin City UniversityDublin‐9Ireland
| | - Frank Barry
- Systems Biology IrelandNUI GalwayIreland
- Regenerative Medicine InstituteNational University of Ireland GalwayIreland
| | - Heinz Peter Nasheuer
- Systems Biology IrelandNUI GalwayIreland
- BiochemistrySchool of Natural Sciences and Centre for Chromosome BiologyNational University of Ireland GalwayIreland
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30
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Random Motion of Chromatin Is Influenced by Lamin A Interconnections. Biophys J 2018; 114:2465-2472. [PMID: 29759373 DOI: 10.1016/j.bpj.2018.04.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/11/2018] [Accepted: 04/19/2018] [Indexed: 01/30/2023] Open
Abstract
Using fluorescence correlation spectroscopy in single-plane illumination microscopy, we investigated the dynamics of chromatin in interphase mouse adult fibroblast cell nuclei under the influence of the intermediate filament protein lamin A. We find that 1) lamin A-eGFP and histone H2A-mRFP show significant comobility, indicating that their motions are clearly interconnected in the nucleus, and 2) that the random motion of histones H2A within the chromatin network is subdiffusive, i.e., the effective diffusion coefficient decreases for slow timescales. Knocking out lamin A changes the diffusion back to normal. Thus, lamin A influences the dynamics of the entire chromatin network. Our conclusion is that lamin A plays a central role in determining the viscoelasticity of the chromatin network and helping to maintain local ordering of interphase chromosomes.
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31
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Lee SF, Klenerman D. Weighing one protein with light. Science 2018; 360:378-379. [PMID: 29700252 DOI: 10.1126/science.aat5851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A light-scattering method allows rapid measurement of the mass of individual proteins
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Affiliation(s)
- Steven F Lee
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
| | - David Klenerman
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
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32
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Stoichiometry and compositional plasticity of the yeast nuclear pore complex revealed by quantitative fluorescence microscopy. Proc Natl Acad Sci U S A 2018; 115:E3969-E3977. [PMID: 29632211 DOI: 10.1073/pnas.1719398115] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The nuclear pore complex (NPC) is an eightfold symmetrical channel providing selective transport of biomolecules across the nuclear envelope. Each NPC consists of ∼30 different nuclear pore proteins (Nups) all present in multiple copies per NPC. Significant progress has recently been made in the characterization of the vertebrate NPC structure. However, because of the estimated size differences between the vertebrate and yeast NPC, it has been unclear whether the NPC architecture is conserved between species. Here, we have developed a quantitative image analysis pipeline, termed nuclear rim intensity measurement (NuRIM), to precisely determine copy numbers for almost all Nups within native NPCs of budding yeast cells. Our analysis demonstrates that the majority of yeast Nups are present at most in 16 copies per NPC. This reveals a dramatic difference to the stoichiometry determined for the human NPC, suggesting that despite a high degree of individual Nup conservation, the yeast and human NPC architecture is significantly different. Furthermore, using NuRIM, we examined the effects of mutations on NPC stoichiometry. We demonstrate for two paralog pairs of key scaffold Nups, Nup170/Nup157 and Nup192/Nup188, that their altered expression leads to significant changes in the NPC stoichiometry inducing either voids in the NPC structure or substitution of one paralog by the other. Thus, our results not only provide accurate stoichiometry information for the intact yeast NPC but also reveal an intriguing compositional plasticity of the NPC architecture, which may explain how differences in NPC composition could arise in the course of evolution.
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33
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State-of-the-Art Fluorescence Fluctuation-Based Spectroscopic Techniques for the Study of Protein Aggregation. Int J Mol Sci 2018; 19:ijms19040964. [PMID: 29570669 PMCID: PMC5979297 DOI: 10.3390/ijms19040964] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 03/17/2018] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are devastating proteinopathies with misfolded protein aggregates accumulating in neuronal cells. Inclusion bodies of protein aggregates are frequently observed in the neuronal cells of patients. Investigation of the underlying causes of neurodegeneration requires the establishment and selection of appropriate methodologies for detailed investigation of the state and conformation of protein aggregates. In the current review, we present an overview of the principles and application of several methodologies used for the elucidation of protein aggregation, specifically ones based on determination of fluctuations of fluorescence. The discussed methods include fluorescence correlation spectroscopy (FCS), imaging FCS, image correlation spectroscopy (ICS), photobleaching ICS (pbICS), number and brightness (N&B) analysis, super-resolution optical fluctuation imaging (SOFI), and transient state (TRAST) monitoring spectroscopy. Some of these methodologies are classical protein aggregation analyses, while others are not yet widely used. Collectively, the methods presented here should help the future development of research not only into protein aggregation but also neurodegenerative diseases.
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Kaliszewski MJ, Shi X, Hou Y, Lingerak R, Kim S, Mallory P, Smith AW. Quantifying membrane protein oligomerization with fluorescence cross-correlation spectroscopy. Methods 2018; 140-141:40-51. [PMID: 29448037 DOI: 10.1016/j.ymeth.2018.02.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/17/2017] [Accepted: 02/07/2018] [Indexed: 01/27/2023] Open
Abstract
Fluorescence cross-correlation spectroscopy (FCCS) is an advanced fluorescence technique that can quantify protein-protein interactions in vivo. Due to the dynamic, heterogeneous nature of the membrane, special considerations must be made to interpret FCCS data accurately. In this study, we describe a method to quantify the oligomerization of membrane proteins tagged with two commonly used fluorescent probes, mCherry (mCH) and enhanced green (eGFP) fluorescent proteins. A mathematical model is described that relates the relative cross-correlation value (fc) to the degree of oligomerization. This treatment accounts for mismatch in the confocal volumes, combinatoric effects of using two fluorescent probes, and the presence of non-fluorescent probes. Using this model, we calculate a ladder of fc values which can be used to determine the oligomer state of membrane proteins from live-cell experimental data. Additionally, a probabilistic mathematical simulation is described to resolve the affinity of different dimeric and oligomeric protein controls.
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Affiliation(s)
| | - Xiaojun Shi
- Department of Chemistry, University of Akron, Akron, OH 44325, USA
| | - Yixuan Hou
- Food Animal Health Research Program, Ohio Agriculture Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, OH 44691, USA
| | - Ryan Lingerak
- Department of Biology, University of Akron, Akron, OH 44325, USA
| | - Soyeon Kim
- Department of Chemistry, University of Akron, Akron, OH 44325, USA
| | - Paul Mallory
- Department of Chemistry, University of Akron, Akron, OH 44325, USA
| | - Adam W Smith
- Department of Chemistry, University of Akron, Akron, OH 44325, USA.
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Vámosi G, Damjanovich L, Bene L. Turning noise into order on the cell surface: Resonant activation of molecular highlighters. Cytometry A 2018; 93:397-401. [PMID: 29389074 DOI: 10.1002/cyto.a.23320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 12/23/2017] [Indexed: 11/08/2022]
Affiliation(s)
- György Vámosi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Damjanovich
- Department of Surgery, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - László Bene
- Department of Surgery, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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36
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Zaffagnini G, Savova A, Danieli A, Romanov J, Tremel S, Ebner M, Peterbauer T, Sztacho M, Trapannone R, Tarafder AK, Sachse C, Martens S. p62 filaments capture and present ubiquitinated cargos for autophagy. EMBO J 2018; 37:embj.201798308. [PMID: 29343546 PMCID: PMC5830917 DOI: 10.15252/embj.201798308] [Citation(s) in RCA: 223] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 01/03/2018] [Accepted: 01/03/2018] [Indexed: 12/14/2022] Open
Abstract
The removal of misfolded, ubiquitinated proteins is an essential part of the protein quality control. The ubiquitin-proteasome system (UPS) and autophagy are two interconnected pathways that mediate the degradation of such proteins. During autophagy, ubiquitinated proteins are clustered in a p62-dependent manner and are subsequently engulfed by autophagosomes. However, the nature of the protein substrates targeted for autophagy is unclear. Here, we developed a reconstituted system using purified components and show that p62 and ubiquitinated proteins spontaneously coalesce into larger clusters. Efficient cluster formation requires substrates modified with at least two ubiquitin chains longer than three moieties and is based on p62 filaments cross-linked by the substrates. The reaction is inhibited by free ubiquitin, K48-, and K63-linked ubiquitin chains, as well as by the autophagosomal marker LC3B, suggesting a tight cross talk with general proteostasis and autophagosome formation. Our study provides mechanistic insights on how substrates are channeled into autophagy.
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Affiliation(s)
- Gabriele Zaffagnini
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Adriana Savova
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Alberto Danieli
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Julia Romanov
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Shirley Tremel
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Michael Ebner
- Department of Structural and Computational Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Thomas Peterbauer
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Martin Sztacho
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Riccardo Trapannone
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
| | - Abul K Tarafder
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Carsten Sachse
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Sascha Martens
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
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Lee HB, Cong A, Leopold H, Currie M, Boersma AJ, Sheets ED, Heikal AA. Rotational and translational diffusion of size-dependent fluorescent probes in homogeneous and heterogeneous environments. Phys Chem Chem Phys 2018; 20:24045-24057. [DOI: 10.1039/c8cp03873b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Macromolecular crowding effects on diffusion depend on the fluorophore structure, the concentration of crowding agents, and the technique employed.
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Affiliation(s)
- Hong Bok Lee
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Anh Cong
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Hannah Leopold
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Megan Currie
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | | | - Erin D. Sheets
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
| | - Ahmed A. Heikal
- Department of Chemistry and Biochemistry
- Swenson College of Science and Engineering
- University of Minnesota Duluth
- Duluth
- USA
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38
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Deciphering CaMKII Multimerization Using Fluorescence Correlation Spectroscopy and Homo-FRET Analysis. Biophys J 2017; 112:1270-1281. [PMID: 28355553 DOI: 10.1016/j.bpj.2017.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/03/2017] [Accepted: 02/03/2017] [Indexed: 11/20/2022] Open
Abstract
While kinases are typically composed of one or two subunits, calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII) is composed of 8-14 subunits arranged as pairs around a central core. It is not clear if the CaMKII holoenzyme functions as an assembly of independent subunits, as catalytic pairs, or as a single unit. One strategy to address this question is to genetically engineer monomeric and dimeric CaMKII and evaluate how their activity compares to the wild-type (WT) holoenzyme. Here a technique that combines fluorescence correlation spectroscopy and homo-FRET analysis was used to characterize assembly mutants of Venus-tagged CaMKIIα to identify a dimeric CaMKII. Spectroscopy was then used to compare how holoenzyme structure and function changes in response to activation with CaM in the dimeric mutant, WT-holoenzyme, and a monomeric CaMKII oligomerization-domain deletion mutant control. CaM triggered an increase in hydrodynamic volume in both WT and dimeric CaMKII without altering subunit stoichiometry or the net homo-FRET between Venus-tagged catalytic domains. Biochemical analysis revealed that the dimeric mutant also functioned like WT holoenzyme in terms of its kinase activity with an exogenous substrate, and for endogenous T286 autophosphorylation. We conclude that the fundamental functional units of CaMKII holoenzyme are paired catalytic-domains.
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A set of enhanced green fluorescent protein concatemers for quantitative determination of nuclear localization signal strength. Anal Biochem 2017; 533:48-55. [PMID: 28669708 DOI: 10.1016/j.ab.2017.06.015] [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] [Received: 01/31/2017] [Revised: 06/08/2017] [Accepted: 06/28/2017] [Indexed: 12/17/2022]
Abstract
Regulated transport of proteins between nucleus and cytoplasm is an important process in the eukaryotic cell. In most cases, active nucleo-cytoplasmic protein transport is mediated by nuclear localization signal (NLS) and/or nuclear export signal (NES) motifs. In this study, we developed a set of vectors expressing enhanced GFP (EGFP) concatemers ranging from 2 to 12 subunits (2xEGFP to 12xEGFP) for analysis of NLS strength. As shown by in gel GFP fluorescence analysis and αGFP Western blotting, EGFP concatemers are expressed as fluorescent full-length proteins in eukaryotic cells. As expected, nuclear localization of concatemeric EGFPs decreases with increasing molecular weight. By oligonucleotide ligation this set of EGFP concatemers can be easily fused to NLS motifs. After determination of intracellular localization of EGFP concatemers alone and fused to different NLS motifs we calculated the size of a hypothetic EGFP concatemer showing a defined distribution of EGFP fluorescence between nucleus and cytoplasm (n/c ratio = 2). Clear differences of the size of the hypothetic EGFP concatemer depending on the fused NLS motif were observed. Therefore, we propose to use the size of this hypothetic concatemer as quantitative indicator for comparing strength of different NLS motifs.
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