1
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Infield DT, Schene ME, Galpin JD, Ahern CA. Genetic Code Expansion for Mechanistic Studies in Ion Channels: An (Un)natural Union of Chemistry and Biology. Chem Rev 2024. [PMID: 39207057 DOI: 10.1021/acs.chemrev.4c00306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Ion channels play central roles in biology and human health by catalyzing the transmembrane flow of electrical charge. These proteins are ideal targets for genetic code expansion (GCE) methods because it is feasible to measure ion channel activity from miniscule amounts of protein and to analyze the resulting data via rigorous, established biophysical methods. In an ideal scenario, the encoding of synthetic, noncanonical amino acids via GCE allows the experimenter to ask questions inaccessible to traditional methods. For this reason, GCE has been successfully applied to a variety of ligand- and voltage-gated channels wherein extensive structural, functional, and pharmacological data exist. Here, we provide a comprehensive summary of GCE as applied to ion channels. We begin with an overview of the methods used to encode noncanonical amino acids in channels and then describe mechanistic studies wherein GCE was used for photochemistry (cross-linking; caged amino acids) and atomic mutagenesis (isosteric manipulation of charge and aromaticity; backbone mutation). Lastly, we cover recent advances in the encoding of fluorescent amino acids for the real-time study of protein conformational dynamics.
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Affiliation(s)
- Daniel T Infield
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Miranda E Schene
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Jason D Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, United States
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2
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Lightle HE, Kafley P, Lewis TR, Wang RE. Site-specific protein conjugates incorporating Para-Azido-L-Phenylalanine for cellular and in vivo imaging. Methods 2023; 219:95-101. [PMID: 37804961 PMCID: PMC10841489 DOI: 10.1016/j.ymeth.2023.10.001] [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: 08/10/2023] [Revised: 10/04/2023] [Accepted: 10/04/2023] [Indexed: 10/09/2023] Open
Abstract
This work features the use of amber suppression-mediated unnatural amino acid (UAA) incorporation into proteins for various imaging purposes. The site-specific incorporation of the UAA, p-azido-L-phenylalanine (pAzF), provides an azide handle that can be used to complete the strain promoted azide-alkyne click cycloaddition (SPAAC) reaction to introduce an imaging modality such as a fluorophore or a positron emission tomography (PET) tracer on the protein of interest (POI). Such methodology can be pursued directly in mammalian cell lines or on proteins expressed in vitro, thereby conferring a homogeneous pool of protein conjugates. A general procedure for UAA incorporation to use with a site-specific protein labeling method is provided allowing for in vitro and in vivo imaging applications based on the representative proteins PTEN and PD-L1. This approach would help elucidate the cellular or in vivo biological activities of the POI.
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Affiliation(s)
- Hailey E Lightle
- Department of Chemistry, Temple University, 1901 N. 13(th) Street, Philadelphia, PA 19122, USA
| | - Parmila Kafley
- Department of Chemistry, Temple University, 1901 N. 13(th) Street, Philadelphia, PA 19122, USA
| | - Todd R Lewis
- Department of Chemistry, Temple University, 1901 N. 13(th) Street, Philadelphia, PA 19122, USA
| | - Rongsheng E Wang
- Department of Chemistry, Temple University, 1901 N. 13(th) Street, Philadelphia, PA 19122, USA.
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3
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Chen W, Gunther TR, Baughman HER, Komives EA. Site-specific incorporation of biophysical probes into NF-ĸB with non-canonical amino acids. Methods 2023; 213:18-25. [PMID: 36940840 PMCID: PMC10688598 DOI: 10.1016/j.ymeth.2023.03.004] [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: 12/13/2022] [Revised: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 03/23/2023] Open
Abstract
The transcription factor NF-ĸB is a central mediator of immune and inflammatory responses. To understand the regulation of NF-ĸB, it is important to probe the underlying thermodynamics, kinetics, and conformational dynamics of the NF-ĸB/IĸBα/DNA interaction network. The development of genetic incorporation of non-canonical amino acids (ncAA) has enabled the installation of biophysical probes into proteins with site specificity. Recent single-molecule FRET (smFRET) studies of NF-ĸB with site-specific labeling via ncAA incorporation revealed the conformational dynamics for kinetic control of DNA-binding mediated by IĸBα. Here we report the design and protocols for incorporating the ncAA p-azidophenylalanine (pAzF) into NF-ĸB and site-specific fluorophore labeling with copper-free click chemistry for smFRET. We also expanded the ncAA toolbox of NF-ĸB to include p-benzoylphenylalanine (pBpa) for UV crosslinking mass spectrometry (XL-MS) and incorporated both pAzF and pBpa into the full-length NF-ĸB RelA subunit which includes the intrinsically disordered transactivation domain.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA.
| | - Tristan R Gunther
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Hannah E R Baughman
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA.
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4
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Du Y, Li L, Zheng Y, Liu J, Gong J, Qiu Z, Li Y, Qiao J, Huo YX. Incorporation of Non-Canonical Amino Acids into Antimicrobial Peptides: Advances, Challenges, and Perspectives. Appl Environ Microbiol 2022; 88:e0161722. [PMID: 36416555 PMCID: PMC9746297 DOI: 10.1128/aem.01617-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The emergence of antimicrobial resistance is a global health concern and calls for the development of novel antibiotic agents. Antimicrobial peptides seem to be promising candidates due to their diverse sources, mechanisms of action, and physicochemical characteristics, as well as the relatively low emergence of resistance. The incorporation of noncanonical amino acids into antimicrobial peptides could effectively improve their physicochemical and pharmacological diversity. Recently, various antimicrobial peptides variants with improved or novel properties have been produced by the incorporation of single and multiple distinct noncanonical amino acids. In this review, we summarize strategies for the incorporation of noncanonical amino acids into antimicrobial peptides, as well as their features and suitabilities. Recent applications of noncanonical amino acid incorporation into antimicrobial peptides are also presented. Finally, we discuss the related challenges and prospects.
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Affiliation(s)
- Yuhui Du
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, China
- MOE International Joint Research Laboratory on Synthetic Biology and Medicines, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, China
| | - Li Li
- School of Chemical Engineering, Sichuan University (SCU), Chengdu, China
| | - Yue Zheng
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China
| | - Jiaheng Liu
- School of Chemical Engineering, Sichuan University (SCU), Chengdu, China
| | - Julia Gong
- Marymount High School, Los Angeles, California, USA
| | - Zekai Qiu
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China
| | - Yanni Li
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China
| | - Jianjun Qiao
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China
| | - Yi-Xin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, China
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5
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Characterising ion channel structure and dynamics using fluorescence spectroscopy techniques. Biochem Soc Trans 2022; 50:1427-1445. [DOI: 10.1042/bst20220605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/21/2022] [Accepted: 10/04/2022] [Indexed: 11/17/2022]
Abstract
Ion channels undergo major conformational changes that lead to channel opening and ion conductance. Deciphering these structure-function relationships is paramount to understanding channel physiology and pathophysiology. Cryo-electron microscopy, crystallography and computer modelling provide atomic-scale snapshots of channel conformations in non-cellular environments but lack dynamic information that can be linked to functional results. Biophysical techniques such as electrophysiology, on the other hand, provide functional data with no structural information of the processes involved. Fluorescence spectroscopy techniques help bridge this gap in simultaneously obtaining structure-function correlates. These include voltage-clamp fluorometry, Förster resonance energy transfer, ligand binding assays, single molecule fluorescence and their variations. These techniques can be employed to unearth several features of ion channel behaviour. For instance, they provide real time information on local and global rearrangements that are inherent to channel properties. They also lend insights in trafficking, expression, and assembly of ion channels on the membrane surface. These methods have the advantage that they can be carried out in either native or heterologous systems. In this review, we briefly explain the principles of fluorescence and how these have been translated to study ion channel function. We also report several recent advances in fluorescence spectroscopy that has helped address and improve our understanding of the biophysical behaviours of different ion channel families.
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6
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Hirschi S, Ward TR, Meier WP, Müller DJ, Fotiadis D. Synthetic Biology: Bottom-Up Assembly of Molecular Systems. Chem Rev 2022; 122:16294-16328. [PMID: 36179355 DOI: 10.1021/acs.chemrev.2c00339] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bottom-up assembly of biological and chemical components opens exciting opportunities to engineer artificial vesicular systems for applications with previously unmet requirements. The modular combination of scaffolds and functional building blocks enables the engineering of complex systems with biomimetic or new-to-nature functionalities. Inspired by the compartmentalized organization of cells and organelles, lipid or polymer vesicles are widely used as model membrane systems to investigate the translocation of solutes and the transduction of signals by membrane proteins. The bottom-up assembly and functionalization of such artificial compartments enables full control over their composition and can thus provide specifically optimized environments for synthetic biological processes. This review aims to inspire future endeavors by providing a diverse toolbox of molecular modules, engineering methodologies, and different approaches to assemble artificial vesicular systems. Important technical and practical aspects are addressed and selected applications are presented, highlighting particular achievements and limitations of the bottom-up approach. Complementing the cutting-edge technological achievements, fundamental aspects are also discussed to cater to the inherently diverse background of the target audience, which results from the interdisciplinary nature of synthetic biology. The engineering of proteins as functional modules and the use of lipids and block copolymers as scaffold modules for the assembly of functionalized vesicular systems are explored in detail. Particular emphasis is placed on ensuring the controlled assembly of these components into increasingly complex vesicular systems. Finally, all descriptions are presented in the greater context of engineering valuable synthetic biological systems for applications in biocatalysis, biosensing, bioremediation, or targeted drug delivery.
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Affiliation(s)
- Stephan Hirschi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Wolfgang P Meier
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, 4058 Basel, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, 3012 Bern, Switzerland.,Molecular Systems Engineering, National Centre of Competence in Research (NCCR), 4002 Basel, Switzerland
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7
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Machado JH, Ting R, Lin JY, Rodriguez EA. A self-labeling protein based on the small ultra-red fluorescent protein, smURFP. RSC Chem Biol 2021; 2:1221-1226. [PMID: 34458834 PMCID: PMC8341759 DOI: 10.1039/d1cb00127b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 06/24/2021] [Indexed: 12/25/2022] Open
Abstract
Self-labeling proteins have revolutionized super-resolution and sensor imaging. Tags recognize a bioorthogonal substrate for covalent attachment. We show the small Ultra-Red Fluorescent Protein (smURFP) is a self-labeling protein. The substrate is fluorogenic, fluoresces when attached, and quenches fluorescent cargo. The smURFP-tag has novel properties for tool development.
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Affiliation(s)
- John-Hanson Machado
- Department of Chemistry, The George Washington University Washington DC 20052 USA
| | - Richard Ting
- Department of Radiology, Molecular Imaging Innovations Institute (MI3), Weill Cornell Medicine New York NY 10065 USA
- Antelope Surgical, Biolabs@NYULangone New York NY 10014 USA
| | - John Y Lin
- Tasmanian School of Medicine, University of Tasmania Hobart Tasmania 7000 Australia
| | - Erik A Rodriguez
- Department of Chemistry, The George Washington University Washington DC 20052 USA
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8
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Brauchi SE, Steinberg XP. Studying ion channel conformation dynamics by encoding coumarin as unnatural amino acid. Methods Enzymol 2021; 653:239-266. [PMID: 34099174 DOI: 10.1016/bs.mie.2021.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Monitoring the conformational changes of proteins is critical to understand their function. Ion channels are membrane-bound minute machines controlling the passage of ions across biological membranes. The precise labeling of ion channels with fluorescent probes allows studying their dynamics and facilitates their characterization by high-resolution optical techniques. Here we describe a protocol for the use of a small fluorescent reporter, incorporated by expansion of the genetic code in the host cell. An important advantage of using small probes is that they are less likely to perturb protein structure, function, and trafficking. In our hands, Tyr-coumarin proved to be useful to measure the conformational changes occurring in the narrow space of the permeation pathway in single capsaicin receptors. The method described here could be directly translated to the study of membrane receptors, non-electrogenic transporters, or membrane-bound enzymes.
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Affiliation(s)
- Sebastian E Brauchi
- Physiology Institute, Universidad Austral de Chile, Valdivia, Chile; Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Valdivia, Chile.
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9
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Blunck R. Determining stoichiometry of ion channel complexes using single subunit counting. Methods Enzymol 2021; 653:377-404. [PMID: 34099180 DOI: 10.1016/bs.mie.2021.02.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
Most membrane proteins, and ion channels in particular, assemble to multimeric biological complexes. This starts with the quarternary structure and continues with the recruitment of auxiliary subunits and oligomerization or clustering of the complexes. While the quarternary structure is best determined by atomic-scale structures, stoichiometry of heteromers and dynamic changes in the assembly cannot necessarily be investigated with structural methods. Here, single subunit counting has proven a powerful method to study the composition of these complexes. Single subunit counting uses the irreversible photodestruction of fluorescent tags as means to directly count a labeled subunit and thereby derive the composition of the assemblies. In this chapter, we discuss single subunit counting and its limitations. We present alternative methods and provide a detailed protocol for recording and analysis of single subunit counting data.
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Affiliation(s)
- Rikard Blunck
- Department of Physics, Université de Montréal, Montréal, QC, Canada.
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10
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Laxman P, Ansari S, Gaus K, Goyette J. The Benefits of Unnatural Amino Acid Incorporation as Protein Labels for Single Molecule Localization Microscopy. Front Chem 2021; 9:641355. [PMID: 33842432 PMCID: PMC8027105 DOI: 10.3389/fchem.2021.641355] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/26/2021] [Indexed: 01/07/2023] Open
Abstract
Single Molecule Localization Microscopy (SMLM) is an imaging method that allows for the visualization of structures smaller than the diffraction limit of light (~200 nm). This is achieved through techniques such as stochastic optical reconstruction microscopy (STORM) and photoactivated localization microscopy (PALM). A large part of obtaining ideal imaging of single molecules is the choice of the right fluorescent label. An upcoming field of protein labeling is incorporating unnatural amino acids (UAAs) with an attached fluorescent dye for precise localization and visualization of individual molecules. For this technique, fluorescent probes are conjugated to UAAs and are introduced into the protein of interest (POI) as a label. Here we contrast this labeling method with other commonly used protein-based labeling methods such as fluorescent proteins (FPs) or self-labeling tags such as Halotag, SNAP-tags, and CLIP-tags, and highlight the benefits and shortcomings of the site-specific incorporation of UAAs coupled with fluorescent dyes in SMLM.
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Affiliation(s)
| | | | | | - Jesse Goyette
- European Molecular Biology Laboratory (EMBL) Australia Node in Single Molecule Sciences, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
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11
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Gupta A, Garreffi BP, Guo M. Facile synthesis of a novel genetically encodable fluorescent α-amino acid emitting greenish blue light. Chem Commun (Camb) 2020; 56:12578-12581. [PMID: 32944728 PMCID: PMC7577945 DOI: 10.1039/d0cc03643a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report the facile synthesis and characterization of a novel fluorescent α-amino acid 4-phenanthracen-9-yl-l-phenylalanine (Phen-AA) (5) that emits greenish blue light in the visible region. This genetically encodable l-α-amino acid has excellent photostability with a 75% quantum yield. It readily gets into human cells, being clearly imaged upon 405 nm laser excitation. The synthetic procedure is resistant to racemization and only involves three simple steps which use mild conditions and generate the Phen-AA in reasonably good yield. It may find broad applications in research, biotechnology, and the pharmaceutical industry.
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Affiliation(s)
- Aakash Gupta
- Department of Chemistry and Biochemistry, UMass Cranberry Health Research Center, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA.
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12
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A rationally designed orthogonal synthetase for genetically encoded fluorescent amino acids. Heliyon 2020; 6:e05140. [PMID: 33083608 PMCID: PMC7550906 DOI: 10.1016/j.heliyon.2020.e05140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 09/25/2020] [Accepted: 09/29/2020] [Indexed: 01/25/2023] Open
Abstract
The incorporation of non-canonical amino acids into proteins has emerged as a promising strategy to manipulate and study protein structure-function relationships with superior precision in vitro and in vivo. To date, fluorescent non-canonical amino acids (f-ncAA) have been successfully incorporated in proteins expressed in bacterial systems, Xenopus oocytes, and HEK-293T cells. Here, we describe the rational generation of a novel orthogonal aminoacyl-tRNA synthetase based on the E. coli tyrosine synthetase that is capable of encoding the f-ncAA tyr-coumarin in HEK-293T cells.
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13
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Bera K, Kamajaya A, Shivange AV, Muthusamy AK, Nichols AL, Borden PM, Grant S, Jeon J, Lin E, Bishara I, Chin TM, Cohen BN, Kim CH, Unger EK, Tian L, Marvin JS, Looger LL, Lester HA. Biosensors Show the Pharmacokinetics of S-Ketamine in the Endoplasmic Reticulum. Front Cell Neurosci 2019; 13:499. [PMID: 31798415 PMCID: PMC6874132 DOI: 10.3389/fncel.2019.00499] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/22/2019] [Indexed: 12/20/2022] Open
Abstract
The target for the “rapid” (<24 h) antidepressant effects of S-ketamine is unknown, vitiating programs to rationally develop more effective rapid antidepressants. To describe a drug’s target, one must first understand the compartments entered by the drug, at all levels—the organ, the cell, and the organelle. We have, therefore, developed molecular tools to measure the subcellular, organellar pharmacokinetics of S-ketamine. The tools are genetically encoded intensity-based S-ketamine-sensing fluorescent reporters, iSKetSnFR1 and iSKetSnFR2. In solution, these biosensors respond to S-ketamine with a sensitivity, S-slope = delta(F/F0)/(delta[S-ketamine]) of 0.23 and 1.9/μM, respectively. The iSKetSnFR2 construct allows measurements at <0.3 μM S-ketamine. The iSKetSnFR1 and iSKetSnFR2 biosensors display >100-fold selectivity over other ligands tested, including R-ketamine. We targeted each of the sensors to either the plasma membrane (PM) or the endoplasmic reticulum (ER). Measurements on these biosensors expressed in Neuro2a cells and in human dopaminergic neurons differentiated from induced pluripotent stem cells (iPSCs) show that S-ketamine enters the ER within a few seconds after appearing in the external solution near the PM, then leaves as rapidly after S-ketamine is removed from the extracellular solution. In cells, S-slopes for the ER and PM-targeted sensors differ by <2-fold, indicating that the ER [S-ketamine] is less than 2-fold different from the extracellular [S-ketamine]. Organelles represent potential compartments for the engagement of S-ketamine with its antidepressant target, and potential S-ketamine targets include organellar ion channels, receptors, and transporters.
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Affiliation(s)
- Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Aron Kamajaya
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Anand K Muthusamy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.,Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Stephen Grant
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Janice Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Elaine Lin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Ishak Bishara
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Theodore M Chin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Elizabeth K Unger
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, United States
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, United States
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
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14
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Shivange AV, Borden PM, Muthusamy AK, Nichols AL, Bera K, Bao H, Bishara I, Jeon J, Mulcahy MJ, Cohen B, O'Riordan SL, Kim C, Dougherty DA, Chapman ER, Marvin JS, Looger LL, Lester HA. Determining the pharmacokinetics of nicotinic drugs in the endoplasmic reticulum using biosensors. J Gen Physiol 2019; 151:738-757. [PMID: 30718376 PMCID: PMC6571994 DOI: 10.1085/jgp.201812201] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/05/2018] [Accepted: 01/09/2019] [Indexed: 12/27/2022] Open
Abstract
Nicotine dependence is thought to arise in part because nicotine permeates into the endoplasmic reticulum (ER), where it binds to nicotinic receptors (nAChRs) and begins an "inside-out" pathway that leads to up-regulation of nAChRs on the plasma membrane. However, the dynamics of nicotine entry into the ER are unquantified. Here, we develop a family of genetically encoded fluorescent biosensors for nicotine, termed iNicSnFRs. The iNicSnFRs are fusions between two proteins: a circularly permutated GFP and a periplasmic choline-/betaine-binding protein engineered to bind nicotine. The biosensors iNicSnFR3a and iNicSnFR3b respond to nicotine by increasing fluorescence at [nicotine] <1 µM, the concentration in the plasma and cerebrospinal fluid of a smoker. We target iNicSnFR3 biosensors either to the plasma membrane or to the ER and measure nicotine kinetics in HeLa, SH-SY5Y, N2a, and HEK293 cell lines, as well as mouse hippocampal neurons and human stem cell-derived dopaminergic neurons. In all cell types, we find that nicotine equilibrates in the ER within 10 s (possibly within 1 s) of extracellular application and leaves as rapidly after removal from the extracellular solution. The [nicotine] in the ER is within twofold of the extracellular value. We use these data to run combined pharmacokinetic and pharmacodynamic simulations of human smoking. In the ER, the inside-out pathway begins when nicotine becomes a stabilizing pharmacological chaperone for some nAChR subtypes, even at concentrations as low as ∼10 nM. Such concentrations would persist during the 12 h of a typical smoker's day, continually activating the inside-out pathway by >75%. Reducing nicotine intake by 10-fold decreases activation to ∼20%. iNicSnFR3a and iNicSnFR3b also sense the smoking cessation drug varenicline, revealing that varenicline also permeates into the ER within seconds. Our iNicSnFRs enable optical subcellular pharmacokinetics for nicotine and varenicline during an early event in the inside-out pathway.
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Affiliation(s)
- Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Philip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Anand K Muthusamy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Aaron L Nichols
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Kallol Bera
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Huan Bao
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Ishak Bishara
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Janice Jeon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Matthew J Mulcahy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Bruce Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Saidhbhe L O'Riordan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Charlene Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA
| | - Edwin R Chapman
- Howard Hughes Medical Institute and Department of Neuroscience, University of Wisconsin, Madison, WI
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
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15
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Jaykumar AB, Caceres PS, Ortiz PA. Single-molecule labeling for studying trafficking of renal transporters. Am J Physiol Renal Physiol 2018; 315:F1243-F1249. [PMID: 30043625 DOI: 10.1152/ajprenal.00082.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability to detect and track single molecules presents the advantage of visualizing the complex behavior of transmembrane proteins with a time and space resolution that would otherwise be lost with traditional labeling and biochemical techniques. Development of new imaging probes has provided a robust method to study their trafficking and surface dynamics. This mini-review focuses on the current technology available for single-molecule labeling of transmembrane proteins, their advantages, and limitations. We also discuss the application of these techniques to the study of renal transporter trafficking in light of recent research.
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Affiliation(s)
- Ankita Bachhawat Jaykumar
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
| | - Paulo S Caceres
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan
| | - Pablo A Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
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16
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Karch S, Broichhagen J, Schneider J, Böning D, Hartmann S, Schmid B, Tripal P, Palmisano R, Alzheimer C, Johnsson K, Huth T. A New Fluorogenic Small-Molecule Labeling Tool for Surface Diffusion Analysis and Advanced Fluorescence Imaging of β-Site Amyloid Precursor Protein-Cleaving Enzyme 1 Based on Silicone Rhodamine: SiR-BACE1. J Med Chem 2018; 61:6121-6139. [PMID: 29939737 DOI: 10.1021/acs.jmedchem.8b00387] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
β-site APP-cleaving enzyme 1 (BACE1) is a major player in the pathogenesis of Alzheimer's disease. Structural and functional fluorescence microscopy offers a powerful approach to learn about the physiology and pathophysiology of this protease. Up to now, however, common labeling techniques require genetic manipulation, use large antibodies, or are not compatible with live cell imaging. Fluorescent small molecules that specifically bind to the protein of interest can overcome these limitations. Herein, we introduce SiR-BACE1, a conjugate of the BACE1 inhibitor S-39 and SiR647, as a novel fluorogenic, tag-free, and antibody-free label for BACE1. We present its chemical development, characterize its photophysical and pharmacologic properties, and evaluate its behavior in solution, in overexpression systems, and in native brain tissue. We demonstrate its applicability in confocal, stimulated emission depletion and dynamic single-molecule microscopy. The first functional studies with SiR-BACE1 on the surface mobility of BACE1 revealed a markedly confined diffusion pattern.
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Affiliation(s)
- Sandra Karch
- Institute of Physiology and Pathophysiology , Friedrich-Alexander-Universität Erlangen-Nürnberg , Universitaetsstrasse 17 , 91054 Erlangen , Germany
| | - Johannes Broichhagen
- Department of Chemical Biology , Max Planck Institute for Medical Research , Jahnstrasse 29 , 69120 Heidelberg , Germany.,Laboratory of Protein Engineering, Institut des Sciences et Ingénierie Chimiques, Sciences de Base , École Polytechnique Fédérale Lausanne , 1015 Lausanne , Switzerland
| | - Julia Schneider
- Institute of Physiology and Pathophysiology , Friedrich-Alexander-Universität Erlangen-Nürnberg , Universitaetsstrasse 17 , 91054 Erlangen , Germany
| | - Daniel Böning
- Max Planck Institute for the Science of Light , Staudtstrasse 2 , 91058 Erlangen , Germany
| | - Stephanie Hartmann
- Institute of Physiology and Pathophysiology , Friedrich-Alexander-Universität Erlangen-Nürnberg , Universitaetsstrasse 17 , 91054 Erlangen , Germany
| | - Benjamin Schmid
- Optical Imaging Centre , Friedrich-Alexander-Universität Erlangen-Nürnberg , Hartmannstrasse 14 , 91052 Erlangen , Germany
| | - Philipp Tripal
- Optical Imaging Centre , Friedrich-Alexander-Universität Erlangen-Nürnberg , Hartmannstrasse 14 , 91052 Erlangen , Germany
| | - Ralf Palmisano
- Optical Imaging Centre , Friedrich-Alexander-Universität Erlangen-Nürnberg , Hartmannstrasse 14 , 91052 Erlangen , Germany
| | - Christian Alzheimer
- Institute of Physiology and Pathophysiology , Friedrich-Alexander-Universität Erlangen-Nürnberg , Universitaetsstrasse 17 , 91054 Erlangen , Germany
| | - Kai Johnsson
- Department of Chemical Biology , Max Planck Institute for Medical Research , Jahnstrasse 29 , 69120 Heidelberg , Germany.,Laboratory of Protein Engineering, Institut des Sciences et Ingénierie Chimiques, Sciences de Base , École Polytechnique Fédérale Lausanne , 1015 Lausanne , Switzerland
| | - Tobias Huth
- Institute of Physiology and Pathophysiology , Friedrich-Alexander-Universität Erlangen-Nürnberg , Universitaetsstrasse 17 , 91054 Erlangen , Germany
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17
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Klippenstein V, Mony L, Paoletti P. Probing Ion Channel Structure and Function Using Light-Sensitive Amino Acids. Trends Biochem Sci 2018; 43:436-451. [PMID: 29650383 DOI: 10.1016/j.tibs.2018.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 02/25/2018] [Accepted: 02/27/2018] [Indexed: 12/13/2022]
Abstract
Approaches to remotely control and monitor ion channel operation with light are expanding rapidly in the biophysics and neuroscience fields. A recent development directly introduces light sensitivity into proteins by utilizing photosensitive unnatural amino acids (UAAs) incorporated using the genetic code expansion technique. The introduction of UAAs results in unique molecular level control and, when combined with the maximal spatiotemporal resolution and poor invasiveness of light, enables direct manipulation and interrogation of ion channel functionality. Here, we review the diverse applications of light-sensitive UAAs in two superfamilies of ion channels (voltage- and ligand-gated ion channels; VGICs and LGICs) and summarize existing UAA tools, their mode of action, potential, caveats, and technical considerations to their use in illuminating ion channel structure and function.
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Affiliation(s)
- Viktoria Klippenstein
- Institut de Biologie de I'ENS (IBENS), CNRS UMR8197, INSERM U1024, Ecole Normale Supérieure, Université PSL, 46 rue d'Ulm, 75005 Paris, France; These authors contributed equally to this work
| | - Laetitia Mony
- Institut de Biologie de I'ENS (IBENS), CNRS UMR8197, INSERM U1024, Ecole Normale Supérieure, Université PSL, 46 rue d'Ulm, 75005 Paris, France; These authors contributed equally to this work
| | - Pierre Paoletti
- Institut de Biologie de I'ENS (IBENS), CNRS UMR8197, INSERM U1024, Ecole Normale Supérieure, Université PSL, 46 rue d'Ulm, 75005 Paris, France.
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18
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Steinberg X, Kasimova MA, Cabezas-Bratesco D, Galpin JD, Ladron-de-Guevara E, Villa F, Carnevale V, Islas L, Ahern CA, Brauchi SE. Conformational dynamics in TRPV1 channels reported by an encoded coumarin amino acid. eLife 2017; 6:e28626. [PMID: 29206105 PMCID: PMC5716661 DOI: 10.7554/elife.28626] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/22/2017] [Indexed: 11/13/2022] Open
Abstract
TRPV1 channels support the detection of noxious and nociceptive input. Currently available functional and structural data suggest that TRPV1 channels have two gates within their permeation pathway: one formed by a 'bundle-crossing' at the intracellular entrance and a second constriction at the selectivity filter. To describe conformational changes associated with channel gating, the fluorescent non-canonical amino acid coumarin-tyrosine was genetically encoded at Y671, a residue proximal to the selectivity filter. Total internal reflection fluorescence microscopy was performed to image the conformational dynamics of the channels in live cells. Photon counts and optical fluctuations from coumarin encoded within TRPV1 tetramers correlates with channel activation by capsaicin, providing an optical marker of conformational dynamics at the selectivity filter. In agreement with the fluorescence data, molecular dynamics simulations display alternating solvent exposure of Y671 in the closed and open states. Overall, the data point to a dynamic selectivity filter that may serve as a gate for permeation.
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Affiliation(s)
- Ximena Steinberg
- Physiology Department, Faculty of MedicineUniversidad Austral de ChileValdiviaChile
| | - Marina A Kasimova
- Institute for Computational Molecular ScienceTemple UniversityPhiladelphiaUnited States
| | | | - Jason D Galpin
- Department of Molecular Physiology and BiophysicsUniversity of IowaIowa CityUnited States
| | - Ernesto Ladron-de-Guevara
- Departamento de Fisiología, Facultad de MedicinaUniversidad Nacional Autónoma de MéxicoCiudad de MéxicoMexico
| | - Federica Villa
- Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB)Politecnico di Milano (POLIMI)MilanoItaly
| | - Vincenzo Carnevale
- Institute for Computational Molecular ScienceTemple UniversityPhiladelphiaUnited States
| | - Leon Islas
- Departamento de Fisiología, Facultad de MedicinaUniversidad Nacional Autónoma de MéxicoCiudad de MéxicoMexico
| | - Christopher A Ahern
- Department of Molecular Physiology and BiophysicsUniversity of IowaIowa CityUnited States
| | - Sebastian E Brauchi
- Physiology Department, Faculty of MedicineUniversidad Austral de ChileValdiviaChile
- Millennium Nucleus of Ion Channels-associated Diseases (MiNICAD)Iniciativa Cientifica MilenioSantiagoChile
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19
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Nano-assembly of amyloid β peptide: role of the hairpin fold. Sci Rep 2017; 7:2344. [PMID: 28539626 PMCID: PMC5443804 DOI: 10.1038/s41598-017-02454-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022] Open
Abstract
Structural investigations have revealed that β hairpin structures are common features in amyloid fibrils, suggesting that these motifs play an important role in amyloid assembly. To test this hypothesis, we characterized the effect of the hairpin fold on the aggregation process using a model β hairpin structure, consisting of two Aβ(14–23) monomers connected by a turn forming YNGK peptide. AFM studies of the assembled aggregates revealed that the hairpin forms spherical structures whereas linear Aβ(14–23) monomers form fibrils. Additionally, an equimolar mixture of the monomer and the hairpin assembles into non-fibrillar aggregates, demonstrating that the hairpin fold dramatically changes the morphology of assembled amyloid aggregates. To understand the molecular mechanism underlying the role of the hairpin fold on amyloid assembly, we performed single-molecule probing experiments to measure interactions between hairpin and monomer and two hairpin complexes. The studies reveal that the stability of hairpin-monomer complexes is much higher than hairpin-hairpin complexes. Molecular dynamics simulations revealed a novel intercalated complex for the hairpin and monomer and Monte Carlo modeling further demonstrated that such nano-assemblies have elevated stability compared with stability of the dimer formed by Aβ(14–23) hairpin. The role of such folding on the amyloid assembly is also discussed.
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20
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Leisle L, Chadda R, Lueck JD, Infield DT, Galpin JD, Krishnamani V, Robertson JL, Ahern CA. Cellular encoding of Cy dyes for single-molecule imaging. eLife 2016; 5:e19088. [PMID: 27938668 PMCID: PMC5207767 DOI: 10.7554/elife.19088] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 12/09/2016] [Indexed: 12/20/2022] Open
Abstract
A general method is described for the site-specific genetic encoding of cyanine dyes as non-canonical amino acids (Cy-ncAAs) into proteins. The approach relies on an improved technique for nonsense suppression with in vitro misacylated orthogonal tRNA. The data show that Cy-ncAAs (based on Cy3 and Cy5) are tolerated by the eukaryotic ribosome in cell-free and whole-cell environments and can be incorporated into soluble and membrane proteins. In the context of the Xenopus laevis oocyte expression system, this technique yields ion channels with encoded Cy-ncAAs that are trafficked to the plasma membrane where they display robust function and distinct fluorescent signals as detected by TIRF microscopy. This is the first demonstration of an encoded cyanine dye as a ncAA in a eukaryotic expression system and opens the door for the analysis of proteins with single-molecule resolution in a cellular environment.
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Affiliation(s)
- Lilia Leisle
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Rahul Chadda
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - John D Lueck
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Daniel T Infield
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Jason D Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Venkatramanan Krishnamani
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Janice L Robertson
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, United States
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21
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Bag SS, Jana S, Pradhan MK. Synthesis, photophysical properties of triazolyl-donor/acceptor chromophores decorated unnatural amino acids: Incorporation of a pair into Leu-enkephalin peptide and application of triazolylperylene amino acid in sensing BSA. Bioorg Med Chem 2016; 24:3579-95. [DOI: 10.1016/j.bmc.2016.05.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/29/2016] [Accepted: 05/30/2016] [Indexed: 02/03/2023]
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22
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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
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23
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24
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Synthesis of fluorescent d-amino acids with 4-acetamidobiphenyl and 4-N,N-dimethylamino-1,8-naphthalimido containing side chains. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.06.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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25
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Cheng M, Zhang W, Yuan J, Luo W, Li N, Lin S, Yang Y, Fang X, Chen PR. Single-molecule dynamics of site-specific labeled transforming growth factor type II receptors on living cells. Chem Commun (Camb) 2015; 50:14724-7. [PMID: 24887482 DOI: 10.1039/c4cc02804j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We achieved single-molecule imaging and tracking of the transforming growth factor type II receptor (TβRII) that was labeled by an organic dye via a genetically encoded unnatural amino acid (UAA) and the copper-free click chemistry. The stoichiometry, mobility and dimerization kinetics of individual TβRII molecules were determined.
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Affiliation(s)
- Ming Cheng
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Key Laboratory of Molecular Nanostructures and Nanotechnology, Chinese Academy of Sciences, Beijing 100190, P. R. China.
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26
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Bosch PJ, Corrêa IR, Sonntag MH, Ibach J, Brunsveld L, Kanger JS, Subramaniam V. Evaluation of fluorophores to label SNAP-tag fused proteins for multicolor single-molecule tracking microscopy in live cells. Biophys J 2015; 107:803-14. [PMID: 25140415 DOI: 10.1016/j.bpj.2014.06.040] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/22/2014] [Accepted: 06/10/2014] [Indexed: 11/19/2022] Open
Abstract
Single-molecule tracking has become a widely used technique for studying protein dynamics and their organization in the complex environment of the cell. In particular, the spatiotemporal distribution of membrane receptors is an active field of study due to its putative role in the regulation of signal transduction. The SNAP-tag is an intrinsically monovalent and highly specific genetic tag for attaching a fluorescent label to a protein of interest. Little information is currently available on the choice of optimal fluorescent dyes for single-molecule microscopy utilizing the SNAP-tag labeling system. We surveyed 6 green and 16 red excitable dyes for their suitability in single-molecule microscopy of SNAP-tag fusion proteins in live cells. We determined the nonspecific binding levels and photostability of these dye conjugates when bound to a SNAP-tag fused membrane protein in live cells. We found that only a limited subset of the dyes tested is suitable for single-molecule tracking microscopy. The results show that a careful choice of the dye to conjugate to the SNAP-substrate to label SNAP-tag fusion proteins is very important, as many dyes suffer from either rapid photobleaching or high nonspecific staining. These characteristics appear to be unpredictable, which motivated the need to perform the systematic survey presented here. We have developed a protocol for evaluating the best dyes, and for the conditions that we evaluated, we find that Dy 549 and CF 640 are the best choices tested for single-molecule tracking. Using an optimal dye pair, we also demonstrate the possibility of dual-color single-molecule imaging of SNAP-tag fusion proteins. This survey provides an overview of the photophysical and imaging properties of a range of SNAP-tag fluorescent substrates, enabling the selection of optimal dyes and conditions for single-molecule imaging of SNAP-tagged fusion proteins in eukaryotic cell lines.
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Affiliation(s)
- Peter J Bosch
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | | | - Michael H Sonntag
- Laboratory of Chemical Biology, Department of Biomedical Engineering, and Institute of Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jenny Ibach
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Luc Brunsveld
- Laboratory of Chemical Biology, Department of Biomedical Engineering, and Institute of Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Johannes S Kanger
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Vinod Subramaniam
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
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27
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Lochner M, Thompson AJ. A review of fluorescent ligands for studying 5-HT3 receptors. Neuropharmacology 2015; 98:31-40. [PMID: 25892507 DOI: 10.1016/j.neuropharm.2015.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022]
Abstract
The use of fluorescence is a valuable and increasingly accessible means of probing the pharmacology and physiology of cells and their receptors. To date, the use of fluorescence-based methods for 5-HT3 receptor research has been quite limited and, although a variety of approaches have been described, these are broadly distributed throughout the literature. In this review we condense these findings into a single, accessible source of reference with the hope of promoting the use of these valuable molecular probes. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'.
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Affiliation(s)
- Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland.
| | - Andrew J Thompson
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK.
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28
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Pless SA, Kim RY, Ahern CA, Kurata HT. Atom-by-atom engineering of voltage-gated ion channels: magnified insights into function and pharmacology. J Physiol 2015; 593:2627-34. [PMID: 25640301 DOI: 10.1113/jphysiol.2014.287714] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/26/2015] [Indexed: 12/12/2022] Open
Abstract
Unnatural amino acid incorporation into ion channels has proven to be a valuable approach to interrogate detailed hypotheses arising from atomic resolution structures. In this short review, we provide a brief overview of some of the basic principles and methods for incorporation of unnatural amino acids into proteins. We also review insights into the function and pharmacology of voltage-gated ion channels that have emerged from unnatural amino acid mutagenesis approaches.
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Affiliation(s)
- Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Robin Y Kim
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | | | - Harley T Kurata
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada
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29
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Leisle L, Valiyaveetil F, Mehl RA, Ahern CA. Incorporation of Non-Canonical Amino Acids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 869:119-51. [PMID: 26381943 DOI: 10.1007/978-1-4939-2845-3_7] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this chapter we discuss the strengths, caveats and technical considerations of three approaches for reprogramming the chemical composition of selected amino acids within a membrane protein. In vivo nonsense suppression in the Xenopus laevis oocyte, evolved orthogonal tRNA and aminoacyl-tRNA synthetase pairs and protein ligation for biochemical production of semisynthetic proteins have been used successfully for ion channel and receptor studies. The level of difficulty for the application of each approach ranges from trivial to technically demanding, yet all have untapped potential in their application to membrane proteins.
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Affiliation(s)
- Lilia Leisle
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Road, 52246, Iowa City, IA, USA
| | - Francis Valiyaveetil
- Department of Physiology and Pharmacology, Oregon Health and Sciences University, 97239, Portland, OR, USA
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University Corvallis, 97331, Corvallis, OR, USA
| | - Christopher A Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Road, 52246, Iowa City, IA, USA.
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30
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Kusch J, Zifarelli G. Patch-clamp fluorometry: electrophysiology meets fluorescence. Biophys J 2014; 106:1250-7. [PMID: 24655500 DOI: 10.1016/j.bpj.2014.02.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/23/2013] [Accepted: 02/06/2014] [Indexed: 12/26/2022] Open
Abstract
Ion channels and transporters are membrane proteins whose functions are driven by conformational changes. Classical biophysical techniques provide insight into either the structure or the function of these proteins, but a full understanding of their behavior requires a correlation of both these aspects in time. Patch-clamp and voltage-clamp fluorometry combine spectroscopic and electrophysiological techniques to simultaneously detect conformational changes and ionic currents across the membrane. Since its introduction, patch-clamp fluorometry has been responsible for invaluable advances in our knowledge of ion channel biophysics. Over the years, the technique has been applied to many different ion channel families to address several biophysical questions with a variety of spectroscopic approaches and electrophysiological configurations. This review illustrates the strength and the flexibility of patch-clamp fluorometry, demonstrating its potential as a tool for future research.
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Affiliation(s)
- Jana Kusch
- Universitätsklinikum Jena, Institut für Physiologie II, Jena, Germany.
| | - Giovanni Zifarelli
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy.
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31
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Ma Z, Du L, Li M. Toward fluorescent probes for G-protein-coupled receptors (GPCRs). J Med Chem 2014; 57:8187-203. [PMID: 24983484 DOI: 10.1021/jm401823z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
G-protein-coupled receptors (GPCRs), a superfamily of cell-surface receptors that are the targets of about 40% of prescription drugs on the market, can sense numerous critical extracellular signals. Recent breakthroughs in structural biology, especially in holo-form X-ray crystal structures, have contributed to our understanding of GPCR signaling. However, actions of GPCRs at the cellular and molecular level, interactions between GPCRs, and the role of protein dynamics in receptor activities still remain controversial. To overcome these dilemmas, fluorescent probes of GPCRs have been employed, which have advantages of in vivo safety and real-time monitoring. Various probes that depend on specific mechanisms and/or technologies have been used to study GPCRs. The present review focuses on surveying the design and applications of fluorescent probes for GPCRs that are derived from small molecules or using protein-labeling techniques, as well as discussing some design strategies for new probes.
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Affiliation(s)
- Zhao Ma
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (MOE), School of Pharmacy, Shandong University , Jinan, Shandong 250012, China
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32
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Dougherty DA, Van Arnam EB. In vivo incorporation of non-canonical amino acids by using the chemical aminoacylation strategy: a broadly applicable mechanistic tool. Chembiochem 2014; 15:1710-20. [PMID: 24990307 DOI: 10.1002/cbic.201402080] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Indexed: 01/05/2023]
Abstract
We describe a strategy for incorporating non-canonical amino acids site-specifically into proteins expressed in living cells, involving organic synthesis to chemically aminoacylate a suppressor tRNA, protein expression in Xenopus oocytes, and monitoring protein function, primarily by electrophysiology. With this protocol, a very wide range of non-canonical amino acids can be employed, allowing both systematic structure-function studies and the incorporation of reactive functionalities. Here, we present an overview of the methodology and examples meant to illustrate the versatility and power of the method as a tool for investigating protein structure and function.
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Affiliation(s)
- Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (USA).
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33
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Arant RJ, Ulbrich MH. Deciphering the subunit composition of multimeric proteins by counting photobleaching steps. Chemphyschem 2014; 15:600-5. [PMID: 24481650 DOI: 10.1002/cphc.201301092] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Indexed: 12/28/2022]
Abstract
The limit of subdiffraction imaging with fluorescent proteins currently lies at 20 nm, and therefore most protein complexes are too small (2-5 nm) to spatially resolve their individual subunits by optical means. However, the number and stoichiometry of subunits within an immobilized protein complex can be resolved by the observation of photobleaching steps of individual fluorophores or co-localization of single-molecule fluorescence emission in multiple colors. We give an overview of the proteins that have been investigated by this approach and the different techniques that can be used to immobilize and label the proteins. This minireview should serve as a guideline for scientists who want to employ single-molecule subunit counting for their research.
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Affiliation(s)
- Ryan J Arant
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 (USA)
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34
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Speight LC, Samanta M, Petersson EJ. Minimalist Approaches to Protein Labelling: Getting the Most Fluorescent Bang for Your Steric Buck. Aust J Chem 2014. [DOI: 10.1071/ch13554] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fluorescence methods allow one to monitor protein conformational changes, protein–protein associations, and proteolysis in real time, at the single molecule level and in living cells. The information gained in such experiments is a function of the spectroscopic techniques used and the strategic placement of fluorophore labels within the protein structure. There is often a trade-off between size and utility for fluorophores, whereby large size can be disruptive to the protein’s fold or function, but valuable characteristics, such as visible wavelength absorption and emission or brightness, require sizable chromophores. Three major types of fluorophore readouts are commonly used: (1) Förster resonance energy transfer (FRET); (2) photoinduced electron transfer (PET); and (3) environmental sensitivity. This review focuses on those probes small enough to be incorporated into proteins during ribosomal translation, which allows the probes to be placed on the interiors of proteins as they are folded during synthesis. The most broadly useful method for doing so is site-specific unnatural amino acid (UAA) mutagenesis. We discuss the use of UAA probes in applications relying on FRET, PET, and environmental sensitivity. We also briefly review other methods of protein labelling and compare their relative merits to UAA mutagenesis. Finally, we discuss small probes that have thus far been used only in synthetic peptides, but which have unusual value and may be candidates for incorporation using UAA methods.
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35
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Speight LC, Muthusamy AK, Goldberg JM, Warner JB, Wissner RF, Willi TS, Woodman BF, Mehl RA, Petersson EJ. Efficient synthesis and in vivo incorporation of acridon-2-ylalanine, a fluorescent amino acid for lifetime and Förster resonance energy transfer/luminescence resonance energy transfer studies. J Am Chem Soc 2013; 135:18806-14. [PMID: 24303933 DOI: 10.1021/ja403247j] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The amino acid acridon-2-ylalanine (Acd) can be a valuable probe of protein conformational change because it is a long lifetime, visible wavelength fluorophore that is small enough to be incorporated during ribosomal biosynthesis. Incorporation of Acd into proteins expressed in Escherichia coli requires efficient chemical synthesis to produce large quantities of the amino acid and the generation of a mutant aminoacyl tRNA synthetase that can selectively charge the amino acid onto a tRNA. Here, we report the synthesis of Acd in 87% yield over five steps from Tyr and the identification of an Acd synthetase by screening candidate enzymes previously evolved from Methanococcus janaschii Tyr synthetase for unnatural amino acid incorporation. Furthermore, we characterize the photophysical properties of Acd, including quenching interactions with select natural amino acids and Förster resonance energy transfer (FRET) interactions with common fluorophores such as methoxycoumarin (Mcm). Finally, we demonstrate the value of incorporation of Acd into proteins, using changes in Acd fluorescence lifetimes, Mcm/Acd FRET, or energy transfer to Eu(3+) to monitor protein folding and binding interactions.
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Affiliation(s)
- Lee C Speight
- University of Pennsylvania , Department of Chemistry, 231 South 34th Street, Philadelphia, Pennsylvania, 19104-6323, United States
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36
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Katayama S, Nakase I, Yano Y, Murayama T, Nakata Y, Matsuzaki K, Futaki S. Effects of pyrenebutyrate on the translocation of arginine-rich cell-penetrating peptides through artificial membranes: Recruiting peptides to the membranes, dissipating liquid-ordered phases, and inducing curvature. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2134-42. [DOI: 10.1016/j.bbamem.2013.05.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 05/16/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
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37
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Zhang WH, Otting G, Jackson CJ. Protein engineering with unnatural amino acids. Curr Opin Struct Biol 2013; 23:581-7. [DOI: 10.1016/j.sbi.2013.06.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 06/12/2013] [Accepted: 06/13/2013] [Indexed: 12/20/2022]
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38
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Kalstrup T, Blunck R. Dynamics of internal pore opening in K(V) channels probed by a fluorescent unnatural amino acid. Proc Natl Acad Sci U S A 2013; 110:8272-7. [PMID: 23630265 PMCID: PMC3657800 DOI: 10.1073/pnas.1220398110] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Atomic-scale models on the gating mechanism of voltage-gated potassium channels (Kv) are based on linear interpolations between static structures of their initial and final state derived from crystallography and molecular dynamics simulations, and, thus, lack dynamic structural information. The lack of information on dynamics and intermediate states makes it difficult to associate the structural with the dynamic functional data obtained with electrophysiology. Although voltage-clamp fluorometry fills this gap, it is limited to sites extracellularly accessible, when the key region for gating is located at the cytosolic side of the channels. Here, we solved this problem by performing voltage-clamp fluorometry with a fluorescent unnatural amino acid. By using an orthogonal tRNA-synthetase pair, the fluorescent unnatural amino acid was incorporated in the Shaker voltage-gated potassium channel at key regions that were previously inaccessible. Thus, we defined which parts act independently and which parts act cooperatively and found pore opening to occur in two sequential transitions.
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Affiliation(s)
- Tanja Kalstrup
- Groupe d’étude des protéines membranaires (GÉPROM) and Departments of Physics and Physiology, Université de Montréal, Montreal, QC, Canada H3C 3J7
| | - Rikard Blunck
- Groupe d’étude des protéines membranaires (GÉPROM) and Departments of Physics and Physiology, Université de Montréal, Montreal, QC, Canada H3C 3J7
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39
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Affiliation(s)
- Tie Xia
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Key Laboratory of Molecular Nanostructures and Nanotechnology, Chinese Academy of Sciences, Beijing 100190, China;
| | - Nan Li
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Key Laboratory of Molecular Nanostructures and Nanotechnology, Chinese Academy of Sciences, Beijing 100190, China;
| | - Xiaohong Fang
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Key Laboratory of Molecular Nanostructures and Nanotechnology, Chinese Academy of Sciences, Beijing 100190, China;
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40
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Pless SA, Ahern CA. Unnatural Amino Acids as Probes of Ligand-Receptor Interactions and Their Conformational Consequences. Annu Rev Pharmacol Toxicol 2013; 53:211-29. [DOI: 10.1146/annurev-pharmtox-011112-140343] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stephan A. Pless
- Department of Anesthesiology, Pharmacology and Therapeutics and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242;
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41
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Kendall EL, Shao C, DeVoe DL. Visualizing the growth and dynamics of liquid-ordered domains during lipid bilayer folding in a microfluidic chip. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3613-3619. [PMID: 22888063 DOI: 10.1002/smll.201200831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 05/29/2012] [Indexed: 06/01/2023]
Abstract
A microfluidic platform enabling optical monitoring of bilayer lipid membrane formation by a new monolayer folding process is described. The thermoplastic chips integrate dried lipid films that are rehydrated by microfluidic perfusion, which enables delivery of lipid-laden air bubbles across a membrane-supporting aperture. As in traditional Montal-Mueller bilayer formation, lipid monolayers are delivered independently to each side of the aperture, thereby allowing asymmetric lipid composition in the resulting bilayer to be achieved. Confocal microscopy is used to image the monolayer folding process, and reveals the growth and dynamics of asymmetric liquid-ordered domains during bilayer stabilization.
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Affiliation(s)
- Eric L Kendall
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
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42
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Abstract
The subunit stoichiometry of heteromeric glycine-gated channels determines fundamental properties of these key inhibitory neurotransmitter receptors; however, the ratio of α1- to β-subunits per receptor remains controversial. We used single-molecule imaging and stepwise photobleaching in Xenopus oocytes to directly determine the subunit stoichiometry of a glycine receptor to be 3α1:2β. This approach allowed us to determine the receptor stoichiometry in mixed populations consisting of both heteromeric and homomeric channels, additionally revealing the quantitative proportions for the two populations.
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43
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Förster resonance energy transfer (FRET) correlates of altered subunit stoichiometry in cys-loop receptors, exemplified by nicotinic α4β2. Int J Mol Sci 2012; 13:10022-10040. [PMID: 22949846 PMCID: PMC3431844 DOI: 10.3390/ijms130810022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 11/17/2022] Open
Abstract
We provide a theory for employing Förster resonance energy transfer (FRET) measurements to determine altered heteropentameric ion channel stoichiometries in intracellular compartments of living cells. We simulate FRET within nicotinic receptors (nAChRs) whose α4 and β2 subunits contain acceptor and donor fluorescent protein moieties, respectively, within the cytoplasmic loops. We predict FRET and normalized FRET (NFRET) for the two predominant stoichiometries, (α4)3(β2)2vs. (α4)2(β2)3. Studying the ratio between FRET or NFRET for the two stoichiometries, minimizes distortions due to various photophysical uncertainties. Within a range of assumptions concerning the distance between fluorophores, deviations from plane pentameric geometry, and other asymmetries, the predicted FRET and NFRET for (α4)3(β2)2 exceeds that of (α4)2(β2)3. The simulations account for published data on transfected Neuro2a cells in which α4β2 stoichiometries were manipulated by varying fluorescent subunit cDNA ratios: NFRET decreased monotonically from (α4)3(β2)2 stoichiometry to mostly (α4)2(β2)3. The simulations also account for previous macroscopic and single-channel observations that pharmacological chaperoning by nicotine and cytisine increase the (α4)2(β2)3 and (α4)3(β2)2 populations, respectively. We also analyze sources of variability. NFRET-based monitoring of changes in subunit stoichiometry can contribute usefully to studies on Cys-loop receptors.
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44
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Richards CI, Luong K, Srinivasan R, Turner SW, Dougherty DA, Korlach J, Lester HA. Live-cell imaging of single receptor composition using zero-mode waveguide nanostructures. NANO LETTERS 2012; 12:3690-4. [PMID: 22668081 PMCID: PMC3397148 DOI: 10.1021/nl301480h] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We exploit the optical and spatial features of subwavelength nanostructures to examine individual receptors on the plasma membrane of living cells. Receptors were sequestered in portions of the membrane projected into zero-mode waveguides. Using single-step photobleaching of green fluorescent protein incorporated into individual subunits, the resulting spatial isolation was used to measure subunit stoichiometry in α4β4 and α4β2 nicotinic acetylcholine and P2X2 ATP receptors. We also show that nicotine and cytisine have differential effects on α4β2 stoichiometry.
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Affiliation(s)
- Christopher I. Richards
- Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125
- Department of Chemistry, University of Kentucky, Chemistry-Physics Building, Lexington, KY 40506
| | - Khai Luong
- Pacific Biosciences, 1380 Willow Road, Menlo Park, CA 94025
| | - Rahul Srinivasan
- Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125
| | | | - Dennis A. Dougherty
- Division of Chemistry & Chemical Engineering 164-30, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125
| | - Jonas Korlach
- Pacific Biosciences, 1380 Willow Road, Menlo Park, CA 94025
| | - Henry A. Lester
- Division of Biology 156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125
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45
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Padilla-Parra S, Tramier M. FRET microscopy in the living cell: Different approaches, strengths and weaknesses. Bioessays 2012; 34:369-76. [DOI: 10.1002/bies.201100086] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 09/15/2011] [Accepted: 09/28/2011] [Indexed: 02/02/2023]
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46
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Schmauder R, Kosanic D, Hovius R, Vogel H. Correlated optical and electrical single-molecule measurements reveal conformational diffusion from ligand binding to channel gating in the nicotinic acetylcholine receptor. Chembiochem 2011; 12:2431-4. [PMID: 21915985 DOI: 10.1002/cbic.201100302] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Indexed: 11/11/2022]
Affiliation(s)
- Ralf Schmauder
- Laboratory of Physical Chemistry of Polymers and Membranes, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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47
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Site-specific in vitro and in vivo incorporation of molecular probes to study G-protein-coupled receptors. Curr Opin Chem Biol 2011; 15:392-8. [DOI: 10.1016/j.cbpa.2011.03.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 03/15/2011] [Accepted: 03/17/2011] [Indexed: 12/20/2022]
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48
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Counting bungarotoxin binding sites of nicotinic acetylcholine receptors in mammalian cells with high signal/noise ratios. Biophys J 2011; 99:L81-3. [PMID: 21081055 DOI: 10.1016/j.bpj.2010.08.076] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 08/18/2010] [Accepted: 08/30/2010] [Indexed: 12/23/2022] Open
Abstract
Nicotinic acetylcholine receptors are some of the most studied synaptic proteins; however, many questions remain that can only be answered using single molecule approaches. Here we report our results from single α7 and neuromuscular junction type nicotinic acetylcholine receptors in mammalian cell membranes. By labeling the receptors with fluorophore-labeled bungarotoxin, we can image individual receptors and count the number of bungarotoxin-binding sites in receptors expressed in HEK 293 cells. Our results indicate that there are two bungarotoxin-binding sites in neuromuscular junction receptors, as expected, and five in α7 receptors, clarifying previous uncertainty. This demonstrates a valuable technique for counting subunits in membrane-bound proteins at the single molecule level, with nonspecialized optics and with higher signal/noise ratios than previous fluorescent protein-based techniques.
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49
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Ulbrich MH. Counting Molecules: Toward Quantitative Imaging. SPRINGER SERIES ON FLUORESCENCE 2011. [DOI: 10.1007/4243_2011_36] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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50
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Hinner MJ, Johnsson K. How to obtain labeled proteins and what to do with them. Curr Opin Biotechnol 2010; 21:766-76. [PMID: 21030243 DOI: 10.1016/j.copbio.2010.09.011] [Citation(s) in RCA: 227] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 09/10/2010] [Accepted: 09/21/2010] [Indexed: 12/20/2022]
Abstract
We review new and established methods for the chemical modification of proteins in living cells and highlight recent applications. The review focuses on tag-mediated protein labeling methods, such as the tetracysteine tag and SNAP-tag, and new developments in this field such as intracellular labeling with lipoic acid ligase. Recent promising advances in the incorporation of unnatural amino acids into proteins are also briefly discussed. We describe new tools using tag-mediated labeling methods including the super-resolution microscopy of tagged proteins, the study of the interactions of proteins and protein domains, the subcellular targeting of synthetic ion sensors, and the generation of new semisynthetic metabolite sensors. We conclude with a view on necessary future developments, with one example being the selective labeling of non-tagged, native proteins in complex protein mixtures.
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Affiliation(s)
- Marlon J Hinner
- Institute of Chemical Sciences and Engineering, Laboratory of Protein Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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