1
|
George A, Indhu M, Ashokraj S, Shanmugam G, Ganesan P, Kamini NR, Ayyadurai N. Genetically encoded dihydroxyphenylalanine coupled with tyrosinase for strain promoted labeling. Bioorg Med Chem 2021; 50:116460. [PMID: 34757293 DOI: 10.1016/j.bmc.2021.116460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 09/25/2021] [Accepted: 10/05/2021] [Indexed: 10/20/2022]
Abstract
Protein modifications through genetic code engineering have a remarkable impact on macromolecule engineering, protein translocation, protein-protein interaction, and cell biology. We used the newly developed molecular biology approach, genetic code engineering, for fine-tuning of proteins for biological availability. Here, we have introduced 3, 4-dihydroxy-l-phenylalanine in recombinant proteins by selective pressure incorporation method for protein-based cell labeling applications. The congener proteins treated with tyrosinase convert 3, 4-dihydroxy-l-phenylalanine to dopaquinone for strain-promoted click chemistry. Initially, the single-step Strain-Promoted Oxidation-Controlled Cyclooctyne-1,2-quinone Cycloaddition was studied using tyrosinase catalyzed congener protein and optimized the temporally controlled conjugation with (1R,8S,9s)-Bicyclo[6.1.0]non-4-yn-9-ylmethanol. Then, the feasibility of tyrosinase-treated congener annexin A5 with easily reactive quinone functional moiety was conjugated with fluorescent tag dibenzocyclooctyne-PEG4-TAMRA for labeling of apoptotic cells. Thus, the congener proteins-based products demonstrate selective cell labeling and apoptosis detection in EA.hy926 cells even after the protein modifications. Hence, genetic code engineering can be coupled with click chemistry to develop various protein-based fluorescent labels.
Collapse
Affiliation(s)
- Augustine George
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India
| | - Mohan Indhu
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Sundarapandian Ashokraj
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Ganesh Shanmugam
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India; Division of Organic and Bio-Organic Chemistry, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India
| | - Ponesakki Ganesan
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India
| | - Numbi Ramudu Kamini
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India
| | - Niraikulam Ayyadurai
- Department of Biochemistry and Biotechnology, Council of Scientific and Industrial Research (CSIR) - Central Leather Research Institute (CLRI), Chennai, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
| |
Collapse
|
2
|
Jia Y, Wang J, Li P, Ma X, Han K. Directionally Modified Fluorophores for Super-Resolution Imaging of Target Enzymes: A Case Study with Carboxylesterases. J Med Chem 2021; 64:16177-16186. [PMID: 34694804 DOI: 10.1021/acs.jmedchem.1c01469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the need for improving the labeling quality of super-resolution imaging, multifarious fluorescent labeling strategies have sprang up. Among them, a small molecule inhibitor-probe (SMI-probe) shows its advancement in fine mapping due to its smaller size and its specific binding to a specific site. Herein, we report a novel protocol of mechanism-guided directional modification of fluorophores into fluorescent inhibitors for enzyme targeting, which could half the size of the SMI-probe. To confirm the feasibility of the strategy, carboxylesterase (hCE) inhibitors are designed and developed. Among the constructed molecule candidates, NIC-4 inhibited both isoforms of hCE1 and hCE2, with IC50 values of 4.56 and 4.11 μM. The CE-targeting specificity of NIC-4 was confirmed by colocalizing with an immunofluorescent probe in fixed-cell confocal imaging. Moreover, NIC-4 was used in live-cell super-resolution microscopy, which indicates dotlike structures instead of the larger staining with the immunofluorescent probe. Moreover, it enables the real-time tracking of dynamic flow of carboxylesterases in live cells.
Collapse
Affiliation(s)
- Yan Jia
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China
| | - Jiayue Wang
- Department of Pharmacy, Peking University Shenzhen Hospital, Shenzhen 518036, China.,College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian 116044, China
| | - Peng Li
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| | - Xiaochi Ma
- College of Pharmacy, Academy of Integrative Medicine, Dalian Medical University, Dalian 116044, China
| | - Keli Han
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China.,Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| |
Collapse
|
3
|
|
4
|
Hoelzel CA, Zhang X. Visualizing and Manipulating Biological Processes by Using HaloTag and SNAP-Tag Technologies. Chembiochem 2020; 21:1935-1946. [PMID: 32180315 PMCID: PMC7367766 DOI: 10.1002/cbic.202000037] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/27/2020] [Indexed: 12/25/2022]
Abstract
Visualizing and manipulating the behavior of proteins is crucial to understanding the physiology of the cell. Methods of biorthogonal protein labeling are important tools to attain this goal. In this review, we discuss advances in probe technology specific for self-labeling protein tags, focusing mainly on the application of HaloTag and SNAP-tag systems. We describe the latest developments in small-molecule probes that enable fluorogenic (no wash) imaging and super-resolution fluorescence microscopy. In addition, we cover several methodologies that enable the perturbation or manipulation of protein behavior and function towards the control of biological pathways. Thus, current technical advances in the HaloTag and SNAP-tag systems means that they are becoming powerful tools to enable the visualization and manipulation of biological processes, providing invaluable scientific insights that are difficult to obtain by traditional methodologies. As the multiplex of self-labeling protein tag systems continues to be developed and expanded, the utility of these protein tags will allow researchers to address previously inaccessible questions at the forefront of biology.
Collapse
Affiliation(s)
- Conner A Hoelzel
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, PA 16802, USA
| | - Xin Zhang
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania, PA 16802, USA
| |
Collapse
|
5
|
Beliu G, Sauer M. A Trojan Horse for live-cell super-resolution microscopy. LIGHT, SCIENCE & APPLICATIONS 2020; 9:2. [PMID: 31934334 PMCID: PMC6944678 DOI: 10.1038/s41377-019-0238-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
New peptide vehicles enable the efficient live-cell labeling of intracellular organelles with cell-impermeable fluorescent probes by simple coincubation, paving the way for refined multicolor super-resolution fluorescence imaging.
Collapse
Affiliation(s)
- Gerti Beliu
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| |
Collapse
|
6
|
Selective Derivatization of Hexahistidine-Tagged Recombinant Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 31347051 DOI: 10.1007/978-3-030-15950-4_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Covalent modification of proteins is extensively used in research and industry for biosensing, medical diagnostics, targeted drug delivery, and many other practical applications. The conventional method for production of protein conjugates has changed little in the last 20 years mostly relying on reactions of side chains of cysteine and lysine residues. Due to the presence of large numbers of similar reactive amino acid residues in proteins, common synthetic methods generally produce complex mixtures of products, which are difficult to separate. An emerging alternative technology for covalent modification of proteins involves formation of a covalent bond with a hexahistidine affinity tag present in a majority of recombinant proteins without interfering with other amino acid residues. The approach is based on formation of a ternary complex of the hexahistidine sequence with a bivalent metal cation chelated by ligand bearing an electrophilic Baylis-Hillman ester group capable of subsequent formation of a covalent bond with one of the histidine residues of the tag. The reaction proceeds under mild reaction conditions in neutral aqueous solutions under high dilutions (10-5 to 10-4 M) providing a stable covalent bond between the label and an imidazole residue in a hexahistidine tag at either C- or N-terminus. Because hexahistidine affinity tag methodology is a de-facto standard for preparation of recombinant proteins our approach can be easily implemented for selective derivatization of these proteins with fluorescent groups, alkynyl groups for "click" reactions, or biotinylation.
Collapse
|
7
|
Ratnatilaka Na Bhuket P, Luckanagul JA, Rojsitthisak P, Wang Q. Chemical modification of enveloped viruses for biomedical applications. Integr Biol (Camb) 2019; 10:666-679. [PMID: 30295307 DOI: 10.1039/c8ib00118a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The unique characteristics of enveloped viruses including nanometer size, consistent morphology, narrow size distribution, versatile functionality and biocompatibility have attracted attention from scientists to develop enveloped viruses for biomedical applications. The biomedical applications of the viral-based nanoparticles include vaccine development, imaging and targeted drug delivery. The modification of the structural elements of enveloped viruses is necessary for the desired functions. Here, we review the chemical approaches that have been utilized to develop bionanomaterials based on enveloped viruses for biomedical applications. We first provide an overview of the structures of enveloped viruses which are composed of nucleic acids, structural and functional proteins, glycan residues and lipid envelope. The methods for modification, including direct conjugation, metabolic incorporation of functional groups and peptide tag insertion, are described based on the biomolecular types of viral components. Layer-by-layer technology is also included in this review to illustrate the non-covalent modification of enveloped viruses. Then, we further elaborate the applications of chemically-modified enveloped viruses, virus-like particles and viral subcomponents in biomedical research.
Collapse
Affiliation(s)
- Pahweenvaj Ratnatilaka Na Bhuket
- Biomedicinal Chemistry Program, Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Phayathai Road, Patumwan, Bangkok, 10330, Thailand
| | | | | | | |
Collapse
|
8
|
Siegl SJ, Vrabel M. Probing the Scope of the Amidine-1,2,3-triazine Cycloaddition as a Prospective Click Ligation Method. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800530] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Sebastian J. Siegl
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences; Flemingovo nám. 2 16610 Prague 6 Czech Republic
| | - Milan Vrabel
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences; Flemingovo nám. 2 16610 Prague 6 Czech Republic
| |
Collapse
|
9
|
Rachel NM, Toulouse JL, Pelletier JN. Transglutaminase-Catalyzed Bioconjugation Using One-Pot Metal-Free Bioorthogonal Chemistry. Bioconjug Chem 2017; 28:2518-2523. [DOI: 10.1021/acs.bioconjchem.7b00509] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Natalie M. Rachel
- PROTEO, Québec Network for Protein Function, Engineering and Applications, Québec, G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H3A 0B8, Canada
| | - Jacynthe L. Toulouse
- PROTEO, Québec Network for Protein Function, Engineering and Applications, Québec, G1V 0A6, Canada
| | - Joelle N. Pelletier
- PROTEO, Québec Network for Protein Function, Engineering and Applications, Québec, G1V 0A6, Canada
- CGCC, Center in Green Chemistry and Catalysis, Montréal, Québec H3A 0B8, Canada
| |
Collapse
|
10
|
Kipper K, Lundius EG, Ćurić V, Nikić I, Wiessler M, Lemke EA, Elf J. Application of Noncanonical Amino Acids for Protein Labeling in a Genomically Recoded Escherichia coli. ACS Synth Biol 2017; 6:233-255. [PMID: 27775882 DOI: 10.1021/acssynbio.6b00138] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Small synthetic fluorophores are in many ways superior to fluorescent proteins as labels for imaging. A major challenge is to use them for a protein-specific labeling in living cells. Here, we report on our use of noncanonical amino acids that are genetically encoded via the pyrrolysyl-tRNA/pyrrolysyl-RNA synthetase pair at artificially introduced TAG codons in a recoded E. coli strain. The strain is lacking endogenous TAG codons and the TAG-specific release factor RF1. The amino acids contain bioorthogonal groups that can be clicked to externally supplied dyes, thus enabling protein-specific labeling in live cells. We find that the noncanonical amino acid incorporation into the target protein is robust for diverse amino acids and that the usefulness of the recoded E. coli strain mainly derives from the absence of release factor RF1. However, the membrane permeable dyes display high nonspecific binding in intracellular environment and the electroporation of hydrophilic nonmembrane permeable dyes severely impairs growth of the recoded strain. In contrast, proteins exposed on the outer membrane of E. coli can be labeled with hydrophilic dyes with a high specificity as demonstrated by labeling of the osmoporin OmpC. Here, labeling can be made sufficiently specific to enable single molecule studies as exemplified by OmpC single particle tracking.
Collapse
Affiliation(s)
- Kalle Kipper
- Department
of Molecular and Cell Biology, Science for Life Laboratory, Uppsala University, Se-751 24 Uppsala, Sweden
| | - Ebba G. Lundius
- Department
of Molecular and Cell Biology, Science for Life Laboratory, Uppsala University, Se-751 24 Uppsala, Sweden
| | - Vladimir Ćurić
- Department
of Molecular and Cell Biology, Science for Life Laboratory, Uppsala University, Se-751 24 Uppsala, Sweden
| | - Ivana Nikić
- Structural
and Computational Biology Unit, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, 69117, Germany
| | - Manfred Wiessler
- Biological
Chemistry, Deutsche Krebsforschungszentrum, Heidelberg, 69120, Germany
| | - Edward A. Lemke
- Structural
and Computational Biology Unit, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, 69117, Germany
| | - Johan Elf
- Department
of Molecular and Cell Biology, Science for Life Laboratory, Uppsala University, Se-751 24 Uppsala, Sweden
| |
Collapse
|
11
|
Bolbat A, Schultz C. Recent developments of genetically encoded optical sensors for cell biology. Biol Cell 2016; 109:1-23. [PMID: 27628952 DOI: 10.1111/boc.201600040] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/06/2016] [Accepted: 09/09/2016] [Indexed: 12/14/2022]
Abstract
Optical sensors are powerful tools for live cell research as they permit to follow the location, concentration changes or activities of key cellular players such as lipids, ions and enzymes. Most of the current sensor probes are based on fluorescence which provides great spatial and temporal precision provided that high-end microscopy is used and that the timescale of the event of interest fits the response time of the sensor. Many of the sensors developed in the past 20 years are genetically encoded. There is a diversity of designs leading to simple or sometimes complicated applications for the use in live cells. Genetically encoded sensors began to emerge after the discovery of fluorescent proteins, engineering of their improved optical properties and the manipulation of their structure through application of circular permutation. In this review, we will describe a variety of genetically encoded biosensor concepts, including those for intensiometric and ratiometric sensors based on single fluorescent proteins, Forster resonance energy transfer-based sensors, sensors utilising bioluminescence, sensors using self-labelling SNAP- and CLIP-tags, and finally tetracysteine-based sensors. We focus on the newer developments and discuss the current approaches and techniques for design and application. This will demonstrate the power of using optical sensors in cell biology and will help opening the field to more systematic applications in the future.
Collapse
Affiliation(s)
- Andrey Bolbat
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
| |
Collapse
|
12
|
Abstract
Methods to visualize, track, measure, and perturb or activate proteins in living cells are central to biomedical efforts to characterize and understand the spatial and temporal underpinnings of life inside cells. Although fluorescent proteins have proven to be extremely useful for in vivo studies of protein function, their utility is inherently limited because their spectral and structural characteristics are interdependent. These limitations have spurred the creation of alternative approaches for the chemical labeling of proteins. We describe in this protocol the use of fluorescence resonance emission transfer (FRET)-quenched DnaE split-inteins for the site-specific labeling and concomitant fluorescence activation of proteins in living cells. We have successfully employed this approach for the site-specific in-cell labeling of the DNA binding domain (DBD) of the transcription factor YY1 using several human cell lines. Moreover, we have shown that this approach can be also used for modifying proteins in order to control their cellular localization and potentially alter their biological activity.
Collapse
Affiliation(s)
- Radhika Borra
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, 90089-9121, USA
| | - Julio A Camarero
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, 90089-9121, USA.
- Department of Chemistry, University of Southern California, Los Angeles, CA, 90089-9121, USA.
| |
Collapse
|
13
|
Tian H, Fürstenberg A, Huber T. Labeling and Single-Molecule Methods To Monitor G Protein-Coupled Receptor Dynamics. Chem Rev 2016; 117:186-245. [DOI: 10.1021/acs.chemrev.6b00084] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- He Tian
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
| | - Alexandre Fürstenberg
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
| | - Thomas Huber
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
| |
Collapse
|
14
|
Griebenow N, Dilmaç AM, Greven S, Bräse S. Site-Specific Conjugation of Peptides and Proteins via Rebridging of Disulfide Bonds Using the Thiol-Yne Coupling Reaction. Bioconjug Chem 2016; 27:911-7. [PMID: 27031217 DOI: 10.1021/acs.bioconjchem.5b00682] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Herein, we describe an extension of our previously reported photomediated disulfide rebridging methodology to the conjugation of peptides and proteins. The methodology proved to be reproducible with various alkynes and different peptides. This study includes the first rebridging of the disulfide bond of a peptide through a thiol-yne reaction with a cyclooctyne. In all cases, the rebridging was proven by MS analyses and confirmed by the absence of olefinic protons on (1)H NMR spectra of the resulting products. Finally, this one-pot reduction thiol-yne conjugation was successfully applied to an antibody Fab fragment with a promising conversion, which set a good ground for the future syntheses of new protein and antibody conjugates.
Collapse
Affiliation(s)
| | - Alicia M Dilmaç
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany
| | | | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany.,Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
| |
Collapse
|
15
|
Niehörster T, Löschberger A, Gregor I, Krämer B, Rahn HJ, Patting M, Koberling F, Enderlein J, Sauer M. Multi-target spectrally resolved fluorescence lifetime imaging microscopy. Nat Methods 2016; 13:257-62. [PMID: 26808668 DOI: 10.1038/nmeth.3740] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/16/2015] [Indexed: 01/09/2023]
Abstract
We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).
Collapse
Affiliation(s)
- Thomas Niehörster
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Anna Löschberger
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Ingo Gregor
- Drittes Physikalisches Institut, Georg-August-Universität, Göttingen, Germany
| | | | | | | | | | - Jörg Enderlein
- Drittes Physikalisches Institut, Georg-August-Universität, Göttingen, Germany
| | - Markus Sauer
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
| |
Collapse
|
16
|
González-Vera JA, Morris MC. Fluorescent Reporters and Biosensors for Probing the Dynamic Behavior of Protein Kinases. Proteomes 2015; 3:369-410. [PMID: 28248276 PMCID: PMC5217393 DOI: 10.3390/proteomes3040369] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/30/2015] [Accepted: 10/23/2015] [Indexed: 12/20/2022] Open
Abstract
Probing the dynamic activities of protein kinases in real-time in living cells constitutes a major challenge that requires specific and sensitive tools tailored to meet the particular demands associated with cellular imaging. The development of genetically-encoded and synthetic fluorescent biosensors has provided means of monitoring protein kinase activities in a non-invasive fashion in their native cellular environment with high spatial and temporal resolution. Here, we review existing technologies to probe different dynamic features of protein kinases and discuss limitations where new developments are required to implement more performant tools, in particular with respect to infrared and near-infrared fluorescent probes and strategies which enable improved signal-to-noise ratio and controlled activation of probes.
Collapse
Affiliation(s)
- Juan A González-Vera
- Cell Cycle Biosensors & Inhibitors, Department of Amino Acids, Peptides and Proteins, Institute of Biomolecules Max Mousseron (IBMM) CNRS-UMR 5247, 15 Avenue Charles Flahault, Montpellier 34093, France.
| | - May C Morris
- Cell Cycle Biosensors & Inhibitors, Department of Amino Acids, Peptides and Proteins, Institute of Biomolecules Max Mousseron (IBMM) CNRS-UMR 5247, 15 Avenue Charles Flahault, Montpellier 34093, France.
| |
Collapse
|
17
|
Mehlenbacher MR, Bou-Abdallah F, Liu XX, Melman A. Calorimetric studies of ternary complexes of Ni(II) and Cu(II) nitrilotriacetic acid and N-acetyloligohistidines. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2015.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
18
|
Ogura A, Tanaka K. Azaelectrocyclization on cell surface: convenient and general approach to chemical biology research. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.02.063] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
19
|
Rashidian M, Dozier JK, Distefano MD. Enzymatic labeling of proteins: techniques and approaches. Bioconjug Chem 2014; 24:1277-94. [PMID: 23837885 DOI: 10.1021/bc400102w] [Citation(s) in RCA: 200] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Site-specific modification of proteins is a major challenge in modern chemical biology due to the large number of reactive functional groups typically present in polypeptides. Because of its importance in biology and medicine, the development of methods for site-specific modification of proteins is an area of intense research. Selective protein modification procedures have been useful for oriented protein immobilization, for studies of naturally occurring post-translational modifications, for creating antibody–drug conjugates, for the introduction of fluorophores and other small molecules on to proteins, for examining protein structure, folding, dynamics, and protein–protein interactions, and for the preparation of protein–polymer conjugates. One of the most important approaches for protein labeling is to incorporate bioorthogonal functionalities into proteins at specific sites via enzymatic reactions. The incorporated tags then enable reactions that are chemoselective, whose functional groups not only are inert in biological media, but also do not occur natively in proteins or other macromolecules. This review article summarizes the enzymatic strategies, which enable site-specific functionalization of proteins with a variety of different functional groups. The enzymes covered in this review include formylglycine generating enzyme, sialyltransferases, phosphopantetheinyltransferases, O-GlcNAc post-translational modification, sortagging, transglutaminase, farnesyltransferase, biotin ligase, lipoic acid ligase, and N-myristoyltransferase.
Collapse
|
20
|
Sauer M. Localization microscopy coming of age: from concepts to biological impact. J Cell Sci 2014; 126:3505-13. [PMID: 23950110 DOI: 10.1242/jcs.123612] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Super-resolution fluorescence imaging by single-molecule photoactivation or photoswitching and position determination (localization microscopy) has the potential to fundamentally revolutionize our understanding of how cellular function is encoded at the molecular level. Among all powerful, high-resolution imaging techniques introduced in recent years, localization microscopy excels because it delivers single-molecule information about molecular distributions, even giving absolute numbers of proteins present in subcellular compartments. This provides insight into biological systems at a molecular level that can yield direct experimental feedback for modeling the complexity of biological interactions. In addition, efficient new labeling methods and strategies to improve localization are emerging that promise to achieve true molecular resolution. This raises localization microscopy as a powerful complementary method for correlative light and electron microscopy experiments.
Collapse
Affiliation(s)
- Markus Sauer
- Department of Biotechnology and Biophysics, Julius-Maximilians-University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| |
Collapse
|
21
|
Rajendran M, Yapici E, Miller LW. Lanthanide-based imaging of protein-protein interactions in live cells. Inorg Chem 2014; 53:1839-53. [PMID: 24144069 PMCID: PMC3944735 DOI: 10.1021/ic4018739] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In order to deduce the molecular mechanisms of biological function, it is necessary to monitor changes in the subcellular location, activation, and interaction of proteins within living cells in real time. Förster resonance energy-transfer (FRET)-based biosensors that incorporate genetically encoded, fluorescent proteins permit high spatial resolution imaging of protein-protein interactions or protein conformational dynamics. However, a nonspecific fluorescence background often obscures small FRET signal changes, and intensity-based biosensor measurements require careful interpretation and several control experiments. These problems can be overcome by using lanthanide [Tb(III) or Eu(III)] complexes as donors and green fluorescent protein (GFP) or other conventional fluorophores as acceptors. Essential features of this approach are the long-lifetime (approximately milliseconds) luminescence of Tb(III) complexes and time-gated luminescence microscopy. This allows pulsed excitation, followed by a brief delay, which eliminates nonspecific fluorescence before the detection of Tb(III)-to-GFP emission. The challenges of intracellular delivery, selective protein labeling, and time-gated imaging of lanthanide luminescence are presented, and recent efforts to investigate the cellular uptake of lanthanide probes are reviewed. Data are presented showing that conjugation to arginine-rich, cell-penetrating peptides (CPPs) can be used as a general strategy for the cellular delivery of membrane-impermeable lanthanide complexes. A heterodimer of a luminescent Tb(III) complex, Lumi4, linked to trimethoprim and conjugated to nonaarginine via a reducible disulfide linker rapidly (∼10 min) translocates into the cytoplasm of Maden Darby canine kidney cells from the culture medium. With this reagent, the intracellular interaction between GFP fused to FK506 binding protein 12 (GFP-FKBP12) and the rapamycin binding domain of mTOR fused to Escherichia coli dihydrofolate reductase (FRB-eDHFR) were imaged at high signal-to-noise ratio with fast (1-3 s) image acquisition using a time-gated luminescence microscope. The data reviewed and presented here show that lanthanide biosensors enable fast, sensitive, and technically simple imaging of protein-protein interactions in live cells.
Collapse
Affiliation(s)
- Megha Rajendran
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607
| | - Engin Yapici
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607
| | - Lawrence W. Miller
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607
| |
Collapse
|
22
|
Liang X, Drueckhammer DG. Arsinous acid as a thiol binding group: potential cysteine peptide tagging functionality that binds a single thiol. NEW J CHEM 2014. [DOI: 10.1039/c3nj01462b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple aryl arsinous acid (ArAs(CH3)OH) was prepared byorthomercuration ofp-cresol followed by Pd-catalyzed reaction with methylarsenic dibromide, purification as the mercaptoethanol adduct, and deprotection using a silver salt.
Collapse
Affiliation(s)
- Xiaofei Liang
- Department of Chemistry
- Stony Brook University
- Stony Brook, USA
| | | |
Collapse
|
23
|
Wang Z, Ding X, Li S, Shi J, Li Y. Engineered fluorescence tags for in vivo protein labelling. RSC Adv 2014. [DOI: 10.1039/c3ra46991c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In vivoprotein labelling with a peptide tag–fluorescent probe system is an important chemical biology strategy for studying protein distribution, interaction and function.
Collapse
Affiliation(s)
- Zhipeng Wang
- School of Medical Engineering
- Hefei University of Technology
- Hefei, China
- Department of Chemistry
- School of Life Sciences
| | - Xiaozhe Ding
- Department of Chemistry
- School of Life Sciences
- Tsinghua University
- Beijing 100084, China
| | - Sijian Li
- School of Medical Engineering
- Hefei University of Technology
- Hefei, China
| | - Jing Shi
- Department of Chemistry
- University of Science and Technology of China
- Hefei, China
| | - Yiming Li
- School of Medical Engineering
- Hefei University of Technology
- Hefei, China
- Department of Chemistry
- School of Life Sciences
| |
Collapse
|
24
|
Jung D, Min K, Jung J, Jang W, Kwon Y. Chemical biology-based approaches on fluorescent labeling of proteins in live cells. MOLECULAR BIOSYSTEMS 2013; 9:862-72. [PMID: 23318293 DOI: 10.1039/c2mb25422k] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Recently, significant advances have been made in live cell imaging owing to the rapid development of selective labeling of proteins in vivo. Green fluorescent protein (GFP) was the first example of fluorescent reporters genetically introduced to protein of interest (POI). While GFP and various types of engineered fluorescent proteins (FPs) have been actively used for live cell imaging for many years, the size and the limited windows of fluorescent spectra of GFP and its variants set limits on possible applications. In order to complement FP-based labeling methods, alternative approaches that allow incorporation of synthetic fluorescent probes to target POIs were developed. Synthetic fluorescent probes are smaller than fluorescent proteins, often have improved photochemical properties, and offer a larger variety of colors. These synthetic probes can be introduced to POIs selectively by numerous approaches that can be largely categorized into chemical recognition-based labeling, which utilizes metal-chelating peptide tags and fluorophore-carrying metal complexes, and biological recognition-based labeling, such as (1) specific non-covalent binding between an enzyme tag and its fluorophore-carrying substrate, (2) self-modification of protein tags using substrate variants conjugated to fluorophores, (3) enzymatic reaction to generate a covalent binding between a small molecule substrate and a peptide tag, and (4) split-intein-based C-terminal labeling of target proteins. The chemical recognition-based labeling reaction often suffers from compromised selectivity of metal-ligand interaction in the cytosolic environment, consequently producing high background signals. Use of protein-substrate interactions or enzyme-mediated reactions generally shows improved specificity but each method has its limitations. Some examples are the presence of large linker protein, restriction on the choice of introducible probes due to the substrate specificity of enzymes, and competitive reaction mediated by an endogenous analogue of the introduced protein tag. These limitations have been addressed, in part, by the split-intein-based labeling approach, which introduces fluorescent probes with a minimal size (~4 amino acids) peptide tag. In this review, the advantages and the limitations of each labeling method are discussed.
Collapse
Affiliation(s)
- Deokho Jung
- Department of Biomedical Engineering, Dongguk University, Seoul, Korea
| | | | | | | | | |
Collapse
|
25
|
Zhou C, Yang S, Liu J, Yu M, Zheng J. Luminescent gold nanoparticles: A new class of nanoprobes for biomedical imaging. Exp Biol Med (Maywood) 2013; 238:1199-209. [DOI: 10.1177/1535370213505825] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Our fundamental understanding of cell biology and early diagnosis of human diseases have been greatly benefited from the development of fluorescent probes. Over the past decade, luminescent gold nanoparticles (AuNPs) with diverse structural parameters including particle size, surface ligands, valence state and grain size have been synthesized and have begun to emerge as a new class of fluorescent probes for bioimaging because of their great biocompatibility, robust photophysical properties and tunable emissions from the visible range to the near infrared region. In this minireview, we summarize the recent progress in applications of different-sized luminescent AuNPs as imaging probes for both in vitro and in vivo levels.
Collapse
Affiliation(s)
- Chen Zhou
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Shengyang Yang
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Jinbin Liu
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Mengxiao Yu
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Jie Zheng
- Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA
| |
Collapse
|
26
|
The degradation of the inwardly rectifying potassium channel, Kir2.1, depends on the expression level: examination with fluorescent proteins. Brain Res 2013; 1528:8-19. [PMID: 23850646 DOI: 10.1016/j.brainres.2013.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 07/01/2013] [Accepted: 07/05/2013] [Indexed: 01/24/2023]
Abstract
The expression of ion channels is regulated by their synthesis as well as degradation, and some ion channels are degraded in an expression level-dependent way. Recently, new techniques of fluorescent proteins have been developed and seem to be useful to study protein degradation. To examine the regulation of the degradation of strongly inwardly rectifying potassium channel (Kir2.1) and the usefulness of the fluorescent proteins, we constructed Kir2.1 fusion proteins with SNAP tag and fluorescent timer (FT). The SNAP tag, which covalently binds to a specific membrane-permeable fluorescent dye, enables a pulse-chase experiment with fluorescence. When the SNAP-Kir2.1 proteins were expressed in 293T cells by low and high expression plasmids, the half-life of the fusion protein expressed by a high-expression plasmid was shorter (18.2±1.9 h) than that expressed by a low-expression plasmid (35.1+2.3h). The addition of Ba(2+), a selective blocker of Kir2.1, slowed the degradation, suggesting a current-dependency of degradation. Consistently, patch-clamp recording showed that cultivation in the presence of Ba(2+) increased the whole cell conductance of SNAP-Kir2.1. Since the fluorescence of FT changes gradually changes from green to red, the green/red ratio should allow us to monitor the changes in the degradation rate of FT-Kir2.1. Using this method, we confirmed the slower degradation by Ba(2+). The results suggest a homeostatic regulation of the degradation of Kir2.1 in the 293T cells, and the usefulness of fluorescence-based methods for examining the degradation of ion channels.
Collapse
|
27
|
van de Linde S, Aufmkolk S, Franke C, Holm T, Klein T, Löschberger A, Proppert S, Wolter S, Sauer M. Investigating cellular structures at the nanoscale with organic fluorophores. ACTA ACUST UNITED AC 2013; 20:8-18. [PMID: 23352135 DOI: 10.1016/j.chembiol.2012.11.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 09/10/2012] [Accepted: 11/02/2012] [Indexed: 01/31/2023]
Abstract
Super-resolution fluorescence imaging can provide insights into cellular structure and organization with a spatial resolution approaching virtually electron microscopy. Among all the different super-resolution methods single-molecule-based localization microscopy could play an exceptional role in the future because it can provide quantitative information, for example, the absolute number of biomolecules interacting in space and time. Here, small organic fluorophores are a decisive factor because they exhibit high fluorescence quantum yields and photostabilities, thus enabling their localization with nanometer precision. Besides past progress, problems with high-density and specific labeling, especially in living cells, and the lack of suited standards and long-term continuous imaging methods with minimal photodamage render the exploitation of the full potential of the method currently challenging.
Collapse
Affiliation(s)
- Sebastian van de Linde
- Department of Biotechnology and Biophysics, Biozentrum, Julius-Maximilians-University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Singh V, Wang S, Chan KM, Clark SA, Kool ET. Genetically encoded multispectral labeling of proteins with polyfluorophores on a DNA backbone. J Am Chem Soc 2013; 135:6184-91. [PMID: 23590213 DOI: 10.1021/ja4004393] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Genetically encoded methods for protein conjugation are of high importance as biological tools. Here we describe the development of a new class of dyes for genetically encoded tagging that add new capabilities for protein reporting and detection via HaloTag methodology. Oligodeoxyfluorosides (ODFs) are short DNA-like oligomers in which the natural nucleic acid bases are replaced by interacting fluorescent chromophores, yielding a broad range of emission colors using a single excitation wavelength. We describe the development of an alkyl halide dehalogenase-compatible chloroalkane linker phosphoramidite derivative that enables the rapid automated synthesis of many possible dyes for protein conjugation. Experiments to test the enzymatic self-conjugation of nine different DNA-like dyes to proteins with HaloTag domains in vitro were performed, and the data confirmed the rapid and efficient covalent labeling of the proteins. Notably, a number of the ODF dyes were found to increase in brightness or change color upon protein conjugation. Tests in mammalian cellular settings revealed that the dyes are functional in multiple cellular contexts, both on the cell surface and within the cytoplasm, allowing protein localization to be imaged in live cells by epifluorescence and laser confocal microscopy.
Collapse
Affiliation(s)
- Vijay Singh
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA
| | | | | | | | | |
Collapse
|
29
|
Sapsford KE, Algar WR, Berti L, Gemmill KB, Casey BJ, Oh E, Stewart MH, Medintz IL. Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology. Chem Rev 2013; 113:1904-2074. [PMID: 23432378 DOI: 10.1021/cr300143v] [Citation(s) in RCA: 818] [Impact Index Per Article: 74.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kim E Sapsford
- Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Choi Y, Kim M, Cho Y, Yun E, Song R. Synthesis, characterization and target protein binding of drug-conjugated quantum dots in vitro and in living cells. NANOTECHNOLOGY 2013; 24:075101. [PMID: 23358444 DOI: 10.1088/0957-4484/24/7/075101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Elucidation of unknown target proteins of a drug is of great importance in understanding cell biology and drug discovery. There have been extensive studies to discover and identify target proteins in the cell. Visualization of targets using drug-conjugated probes has been an important approach to gathering mechanistic information of drug action at the cellular level. As quantum dot (QD) nanocrystals have attracted much attention as a fluorescent probe in the bioimaging area, we prepared drug-conjugated QD to explore the potential of target discovery. As a model drug, we selected a well-known anticancer drug, methotrexate (MTX), which has been known to target dihydrofolate reductase (DHFR) with high affinity binding (K(d) = 0.54 nM). MTX molecules were covalently attached to amino-PEG-polymer-coated QDs. Specific interactions of MTX-conjugated QDs with DHFR were identified using agarose gel electrophoresis and fluorescence microscopy. Cellular uptake of the MTX-conjugated QDs in living CHO cells was investigated with regard to their localization and distribution pattern. MTX-QD was found to be internalized into the cells via caveolae-medicated endocytosis without significant sequestration in endosomes. A colocalization experiment of the MTX-QD conjugate with antiDHFR-TAT-QD also confirmed that MTX-QD binds to the target DHFR. This study showed the potential of the drug-QD conjugate to identify or visualize drug-target interactions in the cell, which is currently of great importance in the area of drug discovery and chemical biology.
Collapse
Affiliation(s)
- Youngseon Choi
- Medicinal Chemistry Laboratory, Institut Pasteur Korea (IP-K), 696 Sampyeong-dong, Bundang-gu,Seongnam-Si, Gyeonggi-Do, Korea
| | | | | | | | | |
Collapse
|
31
|
Urh M, Rosenberg M. HaloTag, a Platform Technology for Protein Analysis. CURRENT CHEMICAL GENOMICS 2012; 6:72-8. [PMID: 23213345 PMCID: PMC3480824 DOI: 10.2174/1875397301206010072] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 08/03/2012] [Accepted: 08/05/2012] [Indexed: 01/01/2023]
Abstract
Understanding protein function and interaction is central to the elucidation of biological processes. Systematic analysis of protein interactions have shown that the eukaryotic proteome is highly interconnected and that biological function frequently depends on the orchestrated action of many proteins. Perturbation of these functions or interactions can lead to various disease states and pharmacologic intervention can result in corrective therapies. The fact that proteins rarely act in isolation, but rather comprise complex machines that stably and/or transiently interact with many different partners at different times, demands the need for robust tools that allow comprehensive global analyses of these events. Here we describe a powerful protein fusion technology, the HaloTag platform, and how it enables the study of many facets of protein biology by offering a broad choice of applications. We review the development of the key aspects of the technology and it's performance in both in vitro and in vivo applications. In particular, we focus on HaloTag's multifunctional utility in protein imaging, protein isolation and display, and in the study of protein complexes and interactions. We demonstrate it's potential to help elucidate important facets of proteomic biology across complex biological systems at the biochemical, cell-based and whole animal level.
Collapse
|
32
|
Mohandessi S, Rajendran M, Magda D, Miller LW. Cell-penetrating peptides as delivery vehicles for a protein-targeted terbium complex. Chemistry 2012; 18:10825-9. [PMID: 22807190 DOI: 10.1002/chem.201201805] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Indexed: 11/07/2022]
Abstract
Release after transmission: Arginine-rich, cell-penetrating peptides (CPPs) mediate cytoplasmic delivery of trimethoprim (TMP)-terbium complex conjugates and selective, intracellular labeling of E. coli dihydrofolate reductase (eDHFR) fusion proteins. A disulfide bond linking CPP and cargo is reduced following uptake. CPP conjugation can be used to deliver otherwise cell-impermeable, ligand-fluorophore conjugates.
Collapse
Affiliation(s)
- Shabnam Mohandessi
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | | | | | | |
Collapse
|
33
|
|
34
|
Borra R, Dong D, Elnagar AY, Woldemariam GA, Camarero JA. In-cell fluorescence activation and labeling of proteins mediated by FRET-quenched split inteins. J Am Chem Soc 2012; 134:6344-53. [PMID: 22404648 DOI: 10.1021/ja300209u] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Methods to visualize, track, and modify proteins in living cells are central for understanding the spatial and temporal underpinnings of life inside cells. Although fluorescent proteins have proven to be extremely useful for in vivo studies of protein function, their utility is inherently limited because their spectral and structural characteristics are interdependent. These limitations have spurred the creation of alternative approaches for the chemical labeling of proteins. We report in this work the use of fluorescence resonance emission transfer (FRET)-quenched DnaE split inteins for the site-specific labeling and concomitant fluorescence activation of proteins in living cells. We have successfully employed this approach for the site-specific in-cell labeling of the DNA binding domain (DBD) of the transcription factor YY1 using several human cell lines. Moreover, we have shown that this approach can be also used for modifying proteins to control their cellular localization and potentially alter their biological activity.
Collapse
Affiliation(s)
- Radhika Borra
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, California 90033, USA
| | | | | | | | | |
Collapse
|
35
|
Mizukami S. Development of molecular imaging tools to investigate protein functions by chemical probe design. Chem Pharm Bull (Tokyo) 2012; 59:1435-46. [PMID: 22130363 DOI: 10.1248/cpb.59.1435] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Molecular imaging technologies, which enable the visualization of the behaviors or functions of biomolecules in living systems, have received considerable attention from life scientists. Novel imaging technologies that overcome the limitations of current imaging techniques are desired. In this review, two independent technologies that were recently developed by the authors are described. The first technology is for smart (19)F magnetic resonance imaging (MRI) probes that were developed for in vivo applications. These probes were developed by exploiting paramagnetic relaxation enhancement in order to detect hydrolase activity. With respect to cellular applications, gene expression in cells was visualized using one of the (19)F MRI probes. It was confirmed that this probe design principle is effective for various hydrolases, and broad applications are expected. The second technology is for practical protein labeling. This labeling method is based on a mutant β-lactamase and its specific labeling probes. Since the probe is fluorescence resonance energy transfer (FRET)-based, this labeling method achieves both specific and fluorogenic labeling of target proteins. In addition, derivatization of the probe enabled the labeling of intracellular proteins and the modification of various functional molecules.
Collapse
Affiliation(s)
- Shin Mizukami
- Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan.
| |
Collapse
|
36
|
van de Linde S, Heilemann M, Sauer M. Live-cell super-resolution imaging with synthetic fluorophores. Annu Rev Phys Chem 2012; 63:519-40. [PMID: 22404589 DOI: 10.1146/annurev-physchem-032811-112012] [Citation(s) in RCA: 201] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Super-resolution imaging methods now can provide spatial resolution that is well below the diffraction limit approaching virtually molecular resolution. They can be applied to biological samples and provide new and exciting views on the structural organization of cells and the dynamics of biomolecular assemblies on wide timescales. These revolutionary developments come with novel requirements for fluorescent probes, labeling techniques, and data interpretation strategies. Synthetic fluorophores have a small size, are available in many colors spanning the whole spectrum, and can easily be chemically modified and used for stoichiometric labeling of proteins in live cells. Because of their brightness, their photostability, and their ability to be operated as photoswitchable fluorophores even in living cells under physiological conditions, synthetic fluorophores have the potential to substantially accelerate the broad application of live-cell super-resolution imaging methods.
Collapse
Affiliation(s)
- Sebastian van de Linde
- Department of Biotechnology and Biophysics, Julius-Maximilians-University Würzburg, Germany
| | | | | |
Collapse
|
37
|
Tanaka K, Yokoi S, Morimoto K, Iwata T, Nakamoto Y, Nakayama K, Koyama K, Fujiwara T, Fukase K. Cell surface biotinylation by azaelectrocyclization: easy-handling and versatile approach for living cell labeling. Bioorg Med Chem 2011; 20:1865-8. [PMID: 22257530 DOI: 10.1016/j.bmc.2011.12.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 12/07/2011] [Accepted: 12/20/2011] [Indexed: 01/21/2023]
Abstract
Versatile method for living cell labeling has been established. Cell surfaces are initially biotinylated by azaelectrocyclization, and then treated with the fluorescence-labeled avidin or the anti-biotin antibody.
Collapse
Affiliation(s)
- Katsunori Tanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Discovery and application of 6π-azaelectrocyclization to natural product synthesis and synthetic biology. Sci China Chem 2011. [DOI: 10.1007/s11426-011-4466-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
39
|
Hoffman MT, Sheung J, Selvin PR. Fluorescence imaging with one nanometer accuracy: in vitro and in vivo studies of molecular motors. Methods Mol Biol 2011; 778:33-56. [PMID: 21809199 DOI: 10.1007/978-1-61779-261-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Traditional microscopy techniques are limited by the wave-like characteristics of light, which dictate that about 250 nm (or roughly half the wavelength of the light) is the smallest distance by which two identical objects can be separated while still being able to distinguish between them. Since most biological molecules are much smaller than this limit, traditional light microscopes are generally not sufficient for single-molecule biological studies. Fluorescence Imaging with One Nanometer Accuracy (FIONA) is a technique that makes possible localization of an object to approximately one nanometer. The FIONA technique is simple in concept; it is built upon the idea that, if enough photons are collected, one can find the exact center of a fluorophore's emission to within a single nanometer and track its motion with a very high level of precision. The center can be localized to approximately (λ/2)/Ö-N, where λ is the wavelength of the light and N is the number of photons collected. When N = 10,000, FIONA achieves an accuracy of 1-2 nm, assuming the background is sufficiently low. FIONA, thus, works best with the use of high-quality dyes and fluorescence stabilization buffers, sensitive detection methods, and special microscopy techniques to reduce background fluorescence. FIONA is particularly well suited to the study of molecular motors, which are enzymes that couple ATP hydrolysis to conformational change and motion. In this chapter, we discuss the practical application of FIONA to molecular motors or other enzymes in biological systems.
Collapse
|
40
|
Manley S, Gunzenhäuser J, Olivier N. A starter kit for point-localization super-resolution imaging. Curr Opin Chem Biol 2011; 15:813-21. [PMID: 22119536 DOI: 10.1016/j.cbpa.2011.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 10/08/2011] [Accepted: 10/17/2011] [Indexed: 01/30/2023]
Abstract
Super-resolution fluorescence imaging can be achieved through the localization of single molecules. By using suitable dyes, optical configurations, and software, it is possible to study a wide variety of biological systems. Here, we summarize the different approaches to labeling proteins. We review proven imaging modalities, and the features of freely available software. Finally, we give an overview of some biological applications. We conclude by synthesizing these different technical aspects into recommendations for standards that the field might apply to ensure quality of images and comparability of algorithms and dyes.
Collapse
Affiliation(s)
- Suliana Manley
- Laboratory of Experimental Biophysics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
| | | | | |
Collapse
|
41
|
Algar WR, Prasuhn DE, Stewart MH, Jennings TL, Blanco-Canosa JB, Dawson PE, Medintz IL. The controlled display of biomolecules on nanoparticles: a challenge suited to bioorthogonal chemistry. Bioconjug Chem 2011; 22:825-58. [PMID: 21585205 DOI: 10.1021/bc200065z] [Citation(s) in RCA: 352] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Interest in developing diverse nanoparticle (NP)-biological composite materials continues to grow almost unabated. This is motivated primarily by the desire to simultaneously exploit the properties of both NP and biological components in new hybrid devices or materials that can be applied in areas ranging from energy harvesting and nanoscale electronics to biomedical diagnostics. The utility and effectiveness of these composites will be predicated on the ability to assemble these structures with control over NP/biomolecule ratio, biomolecular orientation, biomolecular activity, and the separation distance within the NP-bioconjugate architecture. This degree of control will be especially critical in creating theranostic NP-bioconjugates that, as a single vector, are capable of multiple functions in vivo, including targeting, image contrast, biosensing, and drug delivery. In this review, a perspective is given on current and developing chemistries that can provide improved control in the preparation of NP-bioconjugates. The nanoscale properties intrinsic to several prominent NP materials are briefly described to highlight the motivation behind their use. NP materials of interest include quantum dots, carbon nanotubes, viral capsids, liposomes, and NPs composed of gold, lanthanides, silica, polymers, or magnetic materials. This review includes a critical discussion on the design considerations for NP-bioconjugates and the unique challenges associated with chemistry at the biological-nanoscale interface-the liabilities of traditional bioconjugation chemistries being particularly prominent therein. Select bioorthogonal chemistries that can address these challenges are reviewed in detail, and include chemoselective ligations (e.g., hydrazone and Staudinger ligation), cycloaddition reactions in click chemistry (e.g., azide-alkyne cyclyoaddition, tetrazine ligation), metal-affinity coordination (e.g., polyhistidine), enzyme driven modifications (e.g., HaloTag, biotin ligase), and other site-specific chemistries. The benefits and liabilities of particular chemistries are discussed by highlighting relevant NP-bioconjugation examples from the literature. Potential chemistries that have not yet been applied to NPs are also discussed, and an outlook on future developments in this field is given.
Collapse
Affiliation(s)
- W Russ Algar
- Center for Bio/Molecular Science and Engineering, Optical Sciences Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue S.W., Washington, DC 20375, United States
| | | | | | | | | | | | | |
Collapse
|
42
|
Tanaka K, Kitadani M, Fukase K. Target-selective fluorescent "switch-on" protein labeling by 6π-azaelectrocyclization. Org Biomol Chem 2011; 9:5346-9. [PMID: 21691664 DOI: 10.1039/c1ob05320e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Application of azaelectrocyclization and FRET techniques to lysine groups enabled the selective and sensitive detection of a target protein from a mixture, with high fluorescence contrast.
Collapse
Affiliation(s)
- Katsunori Tanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043, Japan.
| | | | | |
Collapse
|
43
|
Abstract
Direct stochastic optical reconstruction microscopy (dSTORM) uses conventional fluorescent probes such as labeled antibodies or chemical tags for subdiffraction resolution fluorescence imaging with a lateral resolution of ∼20 nm. In contrast to photoactivated localization microscopy (PALM) with photoactivatable fluorescent proteins, dSTORM experiments start with bright fluorescent samples in which the fluorophores have to be transferred to a stable and reversible OFF state. The OFF state has a lifetime in the range of 100 milliseconds to several seconds after irradiation with light intensities low enough to ensure minimal photodestruction. Either spontaneously or photoinduced on irradiation with a second laser wavelength, a sparse subset of fluorophores is reactivated and their positions are precisely determined. Repetitive activation, localization and deactivation allow a temporal separation of spatially unresolved structures in a reconstructed image. Here we present a step-by-step protocol for dSTORM imaging in fixed and living cells on a wide-field fluorescence microscope, with standard fluorescent probes focusing especially on the photoinduced fine adjustment of the ratio of fluorophores residing in the ON and OFF states. Furthermore, we discuss labeling strategies, acquisition parameters, and temporal and spatial resolution. The ultimate step of data acquisition and data processing can be performed in seconds to minutes.
Collapse
|
44
|
Sadhu KK, Mizukami S, Hori Y, Kikuchi K. Switching Modulation for Protein Labeling with Activatable Fluorescent Probes. Chembiochem 2011; 12:1299-308. [DOI: 10.1002/cbic.201100137] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 12/14/2022]
|
45
|
Stöhr K, Siegberg D, Ehrhard T, Lymperopoulos K, Öz S, Schulmeister S, Pfeifer AC, Bachmann J, Klingmüller U, Sourjik V, Herten DP. Quenched substrates for live-cell labeling of SNAP-tagged fusion proteins with improved fluorescent background. Anal Chem 2011; 82:8186-93. [PMID: 20815338 DOI: 10.1021/ac101521y] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent developments in fluorescence microscopy raise the demands for bright and photostable fluorescent tags for specific and background free labeling in living cells. Aside from fluorescent proteins and other tagging methods, labeling of SNAP-tagged proteins has become available thereby increasing the pool of potentially applicable fluorescent dyes for specific labeling of proteins. Here, we report on novel conjugates of benzylguanine (BG) which are quenched in their fluorescence and become highly fluorescent upon labeling of the SNAP-tag, the commercial variant of the human O(6)-alkylguanosyltransferase (hAGT). We identified four conjugates showing a strong increase, i.e., >10-fold, in fluorescence intensity upon labeling of SNAP-tag in vitro. Moreover, we screened a subset of nine BG-dye conjugates in living Escherichia coli and found them all suited for labeling of the SNAP-tag. Here, quenched BG-dye conjugates yield a higher specificity due to reduced contribution from excess conjugate to the fluorescence signal. We further extended the application of these conjugates by labeling a SNAP-tag fusion of the Tar chemoreceptor in live E. coli cells and the eukaryotic transcription factor STAT5b in NIH 3T3 mouse fibroblast cells. Aside from the labeling efficiency and specificity in living cells, we discuss possible mechanisms that might be responsible for the changes in fluorescence emission upon labeling of the SNAP-tag, as well as problems we encountered with nonspecific labeling with certain conjugates in eukaryotic cells.
Collapse
Affiliation(s)
- Katharina Stöhr
- CellNetworks Cluster and Institute of Physical Chemistry, Heidelberg University, Im Neuenheimer Feld 267, D-69120 Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy (including stimulated Raman scattering and two-photon absorption) and pump-probe microscopy (including excited-state absorption, stimulated emission, and ground-state depletion), provides new image contrasts for nonfluorescent species. Thanks to the high-frequency modulation transfer scheme, these imaging techniques exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles and excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques.
Collapse
Affiliation(s)
- Wei Min
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge 02138, MA
| | - Christian W. Freudiger
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge 02138, MA
- Department of Physics, Harvard University, Cambridge 02138, MA
| | - Sijia Lu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge 02138, MA
| | - X. Sunney Xie
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge 02138, MA
| |
Collapse
|
47
|
Abstract
Within only a few years super-resolution fluorescence imaging based on single-molecule localization and image reconstruction has attracted considerable interest because it offers a comparatively simple way to achieve a substantially improved optical resolution down to ∼20 nm in the image plane. Since super-resolution imaging methods such as photoactivated localization microscopy, fluorescence photoactivation localization microscopy, stochastic optical reconstruction microscopy, and direct stochastic optical reconstruction microscopy rely critically on exact fitting of the centre of mass and the shape of the point-spread-function of isolated emitters unaffected by neighbouring fluorophores, controlled photoswitching or photoactivation of fluorophores is the key parameter for resolution improvement. This review will explain the principles and requirements of single-molecule based localization microscopy, and compare different super-resolution imaging concepts and highlight their strengths and limitations with respect to applications in fixed and living cells with high spatio-temporal resolution.
Collapse
|
48
|
Nguyen UTT, Goody RS, Alexandrov K. Understanding and exploiting protein prenyltransferases. Chembiochem 2010; 11:1194-201. [PMID: 20432425 DOI: 10.1002/cbic.200900727] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Uyen T T Nguyen
- Laboratory of Synthetic Protein Chemistry, The Rockefeller University, New York, NY 10065, USA
| | | | | |
Collapse
|
49
|
Tanaka K, Minami K, Tahara T, Fujii Y, Siwu ERO, Nozaki S, Onoe H, Yokoi S, Koyama K, Watanabe Y, Fukase K. Electrocyclization-based labeling allows efficient in vivo imaging of cellular trafficking. ChemMedChem 2010; 5:841-5. [PMID: 20408160 DOI: 10.1002/cmdc.201000027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Katsunori Tanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka-shi, Osaka 560-0043, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Bockhorn JJ, Lazar KL, Gasser AJ, Luther LM, Qahwash IM, Chopra N, Meredith SC. Novel semisynthetic method for generating full length beta-amyloid peptides. Biopolymers 2010; 94:511-20. [PMID: 20593467 DOI: 10.1002/bip.21391] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacterial expression of full length beta-amyloid (Abeta) is problematic because of toxicity and poor solubility of the expressed protein, and a strong tendency of Met35 to become oxidized in inclusion bodies. We have developed a semisynthetic method in which Abeta1-29 is expressed in bacteria as part of a fusion protein with a C-terminal intein and Chitin-Binding Domain (CBD). There is also a single residue, N-terminal Met extension. The protein, Met-Abeta1-29-Intein-CBD, is well expressed and highly water-soluble. After binding of the expressed protein to Chitin beads, treatment with sodium 2-mercapto-ethane sulfonate (MESNA) yields Met-Abeta1-29-MESNA, with a C-terminal thioester suitable for native chemical ligation. Met-Abeta1-29-MESNA is first subjected to CNBr cleavage, which removes the N-terminal Met residue, but leaves the thioester intact. We synthesized NH2-A30C-Abeta30-40, which has an N-terminal Cys residue and is the partner for native chemical ligation with Met-Abeta1-29-MESNA. Native chemical ligation proceeds rapidly and efficiently (>90% yield) to give A30C-Abeta1-40. The final step is selective desulfurization using Raney-Ni, which also proceeds rapidly and efficiently (>90% yield) to give native sequence Abeta1-40. Overall, this system is highly efficient, and can yield approximately 8-10 mg of pure Abeta1-40 from one liter of bacterial culture medium. This procedure is adaptable for producing other Abeta peptides. We have also expressed an Abeta construct bearing a point mutation associated with one type of familial Alzheimer's Disease, the Iowa mutation, i.e., Met-D23N-Abeta1-29-Intein-CBD. Since expression of the intein-containing fusion protein is robust in minimal media as well as standard enriched media, this procedure also can be readily modified for incorporating 15N or 13C labels for NMR. Future work will also include extending this system to longer Abeta peptides, such as Abeta1-42.
Collapse
Affiliation(s)
- Jessica J Bockhorn
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | |
Collapse
|