1
|
Budiarta M, Streit M, Beliu G. Site-specific protein labeling strategies for super-resolution microscopy. Curr Opin Chem Biol 2024; 80:102445. [PMID: 38490137 DOI: 10.1016/j.cbpa.2024.102445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 02/28/2024] [Accepted: 02/28/2024] [Indexed: 03/17/2024]
Abstract
Super-resolution microscopy (SRM) has transformed our understanding of proteins' subcellular organization and revealed cellular details down to nanometers, far beyond conventional microscopy. While localization precision is independent of the number of fluorophores attached to a biomolecule, labeling density is a decisive factor for resolving complex biological structures. The average distance between adjacent fluorophores should be less than half the desired spatial resolution for optimal clarity. While this was not a major limitation in recent decades, the success of modern microscopy approaching molecular resolution down to the single-digit nanometer range will depend heavily on advancements in fluorescence labeling. This review highlights recent advances and challenges in labeling strategies for SRM, focusing on site-specific labeling technologies. These advancements are crucial for improving SRM precision and expanding our understanding of molecular interactions.
Collapse
Affiliation(s)
- Made Budiarta
- Rudolf Virchow Center, Research Center for Integrative and Translational Bioimaging, University of Würzburg, 97080 Würzburg, Germany
| | - Marcel Streit
- Rudolf Virchow Center, Research Center for Integrative and Translational Bioimaging, University of Würzburg, 97080 Würzburg, Germany
| | - Gerti Beliu
- Rudolf Virchow Center, Research Center for Integrative and Translational Bioimaging, University of Würzburg, 97080 Würzburg, Germany; Interdisciplinary Institute for Neuroscience, University of Bordeaux, CNRS, UMR 5297, 33076 Bordeaux, France.
| |
Collapse
|
2
|
Kaushik V, Chadda R, Kuppa S, Pokhrel N, Vayyeti A, Grady S, Arnatt C, Antony E. Fluorescent human RPA to track assembly dynamics on DNA. Methods 2024; 223:95-105. [PMID: 38301751 PMCID: PMC10923064 DOI: 10.1016/j.ymeth.2024.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024] Open
Abstract
DNA metabolic processes including replication, repair, recombination, and telomere maintenance occur on single-stranded DNA (ssDNA). In each of these complex processes, dozens of proteins function together on the ssDNA template. However, when double-stranded DNA is unwound, the transiently open ssDNA is protected and coated by the high affinity heterotrimeric ssDNA binding Replication Protein A (RPA). Almost all downstream DNA processes must first remodel/remove RPA or function alongside to access the ssDNA occluded under RPA. Formation of RPA-ssDNA complexes trigger the DNA damage checkpoint response and is a key step in activating most DNA repair and recombination pathways. Thus, in addition to protecting the exposed ssDNA, RPA functions as a gatekeeper to define functional specificity in DNA maintenance and genomic integrity. RPA achieves functional dexterity through a multi-domain architecture utilizing several DNA binding and protein-interaction domains connected by flexible linkers. This flexible and modular architecture enables RPA to adopt a myriad of configurations tailored for specific DNA metabolic roles. To experimentally capture the dynamics of the domains of RPA upon binding to ssDNA and interacting proteins we here describe the generation of active site-specific fluorescent versions of human RPA (RPA) using 4-azido-L-phenylalanine (4AZP) incorporation and click chemistry. This approach can also be applied to site-specific modifications of other multi-domain proteins. Fluorescence-enhancement through non-canonical amino acids (FEncAA) and Förster Resonance Energy Transfer (FRET) assays for measuring dynamics of RPA on DNA are also described. The fluorescent human RPA described here will enable high-resolution structure-function analysis of RPA-ssDNA interactions.
Collapse
Affiliation(s)
- Vikas Kaushik
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Rahul Chadda
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Sahiti Kuppa
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Nilisha Pokhrel
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Abhinav Vayyeti
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Scott Grady
- Department of Chemistry, St. Louis University, St. Louis, MO 63103, USA
| | - Chris Arnatt
- Department of Chemistry, St. Louis University, St. Louis, MO 63103, USA
| | - Edwin Antony
- Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, MO 63104, USA.
| |
Collapse
|
3
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
4
|
Feng D, Feng G, Song Y, Wüthrich K. Solvent accessibility of a GPCR transmembrane domain probed by in-membrane chemical modification (IMCM). FEBS Lett 2023. [PMID: 37073622 DOI: 10.1002/1873-3468.14627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/14/2023] [Accepted: 04/06/2023] [Indexed: 04/20/2023]
Abstract
G protein-coupled receptors (GPCRs) transmit signals from drugs across cell membranes, leading to associated physiological effects. To study the structural basis of the transmembrane signaling, in-membrane chemical modification (IMCM) has previously been introduced for 19 F-labeling of GPCRs expressed in Spodoptera frugiperda (Sf9) insect cells. Here, IMCM is used with the A2A adenosine receptor (A2A AR) expressed in Pichia pastoris; 19 F-NMR revealed nearly complete solvent protection of the A2A AR transmembrane domain in the membrane and in 2,2-didecylpropane-1,3-bis-β-D-maltopyranoside (LMNG)/cholesteryl hemisuccinate (CHS) micelles, and extensive solvent accessibility for A2A AR in n-dodecyl β-D-maltoside (DDM)/CHS micelles. No Cys residue dominated non-specific labeling with 2,2,2-trifluoroethanethiol. These observations yield an improved protocol for IMCM 19 F-labeling of GPCRs and new insights into variable solvent accessibility for function-related characterization of GPCRs.
Collapse
Affiliation(s)
- Dandan Feng
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Guanru Feng
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Yanzhuo Song
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- Present address: Meitek Technology (Qingdao) Co., Ltd., Qingdao, Shandong Province, China
| | - Kurt Wüthrich
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, 92037, USA
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093, Zürich, Switzerland
| |
Collapse
|
5
|
Biswas A, Peng YF, Kaushik V, Origanti S. Site-specific labeling of SBDS to monitor interactions with the 60S ribosomal subunit. Methods 2023; 211:68-72. [PMID: 36781034 DOI: 10.1016/j.ymeth.2023.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/13/2023] Open
Abstract
The Shwachman-Diamond syndrome (SDS) is a rare inherited ribosomopathy that is predominantly caused by mutations in the Shwachman-Bodian-Diamond Syndrome gene (SBDS). SBDS is a ribosomal maturation factor that is essential for the release of eukaryotic translation initiation factor 6 (eIF6) from 60S ribosomal subunits during the late stages of 60S maturation. Release of eIF6 is critical to permit inter-subunit interactions between the 60S and 40S subunits and to form translationally competent 80S monosomes. SBDS has three key domains that are highly flexible and adopt varied conformations in solution. To better understand the domain dynamics of SBDS upon binding to 60S and to assess the effects of SDS-disease specific mutations, we aimed to site-specifically label individual domains of SBDS. Here we detail the generation of a fluorescently labeled SBDS to monitor the dynamics of select domains upon binding to 60S. We describe the incorporation of 4-azido-l-phenylalanine (4AZP), a noncanonical amino acid in human SBDS. Site-specific labeling of SBDS using fluorophore and assessment of 60S binding activity are also described. Such labeling approaches to capture the interactions of individual domains of SBDS with 60S are also applicable to study the dynamics of other multi-domain proteins that interact with the ribosomal subunits.
Collapse
|
6
|
Niu J, Hagen J, Yu F, Kalyuzhny AE, Tsourkas A. Labeling of Phospho-Specific Antibodies with oYo-Link® Epitope Tags for Multiplex Immunostaining. Methods Mol Biol 2023; 2593:113-126. [PMID: 36513927 PMCID: PMC10730302 DOI: 10.1007/978-1-0716-2811-9_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Spatial proteomics has recently garnered significant interest, as it offers to provide unprecedented insight into biological processes in both health and disease, by connecting protein expression patterns from the subcellular level to the tissue or even organism level. These high-content approaches generally rely on a high degree of multiplexing, whereby multiple proteins can be detected simultaneously. The most versatile multiplexing approaches utilize antibodies to confer specificity for various intracellular proteins of interest. Therefore, these methods must be able to differentiate many antibodies at once. In this chapter, we describe a simple and rapid approach to labeling antibodies with distinct epitope tags in a site-specific manner. This allows multiple antibodies, even from the same host species, to be uniquely identified and detected and offers a simple approach for spatial proteomic applications.
Collapse
Affiliation(s)
| | | | | | | | - Andrew Tsourkas
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
7
|
Chen Y, Zhu S, Fu J, Lin J, Sun Y, Lv G, Xie M, Xu T, Qiu L. Development of a radiolabeled site-specific single-domain antibody positron emission tomography probe for monitoring PD-L1 expression in cancer. J Pharm Anal 2022; 12:869-78. [PMID: 36605578 DOI: 10.1016/j.jpha.2022.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 09/06/2022] [Accepted: 09/13/2022] [Indexed: 01/07/2023] Open
Abstract
Despite advances in immunotherapy for the treatment of cancers, not all patients can benefit from programmed cell death ligand 1 (PD-L1) immune checkpoint blockade therapy. Anti-PD-L1 therapeutic effects reportedly correlate with the PD-L1 expression level; hence, accurate detection of PD-L1 expression can guide immunotherapy to achieve better therapeutic effects. Therefore, based on the high affinity antibody Nb109, a new site-specifically radiolabeled tracer, 68Ga-NODA-cysteine, aspartic acid, and valine (CDV)-Nb109, was designed and synthesized to accurately monitor PD-L1 expression. The tracer 68Ga-NODA-CDV-Nb109 was obtained using a site-specific conjugation strategy with a radiochemical yield of about 95% and radiochemical purity of 97%. It showed high affinity for PD-L1 with a dissociation constant of 12.34 ± 1.65 nM. Both the cell uptake assay and positron emission tomography (PET) imaging revealed higher tracer uptake in PD-L1-positive A375-hPD-L1 and U87 tumor cells than in PD-L1-negative A375 tumor cells. Meanwhile, dynamic PET imaging of a NCI-H1299 xenograft indicated that doxorubicin could upregulate PD-L1 expression, allowing timely interventional immunotherapy. In conclusion, this tracer could sensitively and dynamically monitor changes in PD-L1 expression levels in different cancers and help screen patients who can benefit from anti-PD-L1 immunotherapy.
Collapse
|
8
|
Abstract
Fast and efficient site-specific labeling of long RNAs is one of the main bottlenecks limiting distance measurements by means of Förster resonance energy transfer (FRET) or electron paramagnetic resonance (EPR) spectroscopy. Here, we present an optimized protocol for dual end-labeling with different fluorophores at the same time meeting the restrictions of highly labile and degradation-sensitive RNAs. We describe in detail the dual-labeling of a catalytically active wild-type group II intron as a typical representative of long functional RNAs. The modular procedure chemically activates the 5'-phosphate and the 3'-ribose for bioconjugation with a pair of fluorophores, as shown herein, or with spin labels. The mild reaction conditions preserve the structural and functional integrity of the biomacromolecule and results in covalent, dual-labeled RNA in its pre-catalytic state in yields suitable for both ensemble and single-molecule FRET experiments.
Collapse
Affiliation(s)
- Esra Ahunbay
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Fabio D Steffen
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | | | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
9
|
CHEN W, YOUNIS MH, ZHAO Z, CAI W. Recent biomedical advances enabled by HaloTag technology. BIOCELL 2022; 46:1789-1801. [PMID: 35601815 PMCID: PMC9119580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The knowledge of interactions among functional proteins helps researchers understand disease mechanisms and design potential strategies for treatment. As a general approach, the fluorescent and affinity tags were employed for exploring this field by labeling the Protein of Interest (POI). However, the autofluorescence and weak binding strength significantly reduce the accuracy and specificity of these tags. Conversely, HaloTag, a novel self-labeling enzyme (SLE) tag, could quickly form a covalent bond with its ligand, enabling fast and specific labeling of POI. These desirable features greatly increase the accuracy and specificity, making the HaloTag a valuable system for various applications ranging from imaging to immobilization of POI. Notably, the HaloTag technique has already been successfully employed in a series of studies with excellent efficiency. In this review, we summarize the development of HaloTag and recent advanced investigations associated with HaloTag, including in vitro imaging (e.g., POI imaging, cellular condition monitoring, microorganism imaging, system development), in vivo imaging, biomolecule immobilization (e.g., POI collection, protein/nuclear acid interaction and protein structure analysis), targeted degradation (e.g., L-AdPROM), and more. We also present a systematic discussion regarding the future direction and challenges of the HaloTag technique.
Collapse
Affiliation(s)
- Weiyu CHEN
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322000, China,International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, 322000, China
| | - Muhsin H. YOUNIS
- Departments of Radiology and Medical Physics, University of Wisconsin—Madison, Madison, WI, 53705, USA
| | - Zhongkuo ZHAO
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322000, China,Address correspondence to: Zhongkuo Zhao, ; Weibo Cai,
| | - Weibo CAI
- Departments of Radiology and Medical Physics, University of Wisconsin—Madison, Madison, WI, 53705, USA,Address correspondence to: Zhongkuo Zhao, ; Weibo Cai,
| |
Collapse
|
10
|
Hansen SB, Andersen KR. Introducing Cysteines into Nanobodies for Site-Specific Labeling. Methods Mol Biol 2022; 2446:327-343. [PMID: 35157281 DOI: 10.1007/978-1-0716-2075-5_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We have developed a generally applicable methodology for cysteine mutagenesis of nanobody (Nb) framework region serine residues. This strategy allows for subsequent labeling with thiol-reactive compounds without disrupting Nb antigen binding. We provide a protocol for production, labeling, and affinity determination of cysteine-engineered Nbs (cys-Nbs) with Alexa Fluor 488-maleimide and the mercury compound para-chloromercuribenzoic acid (PCMB). Alexa Fluor 488- and PCMB-labeled cys-Nbs can be used for immunofluorescence microscopy and experimental phasing in crystallography, respectively.
Collapse
Affiliation(s)
- Simon Boje Hansen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | | |
Collapse
|
11
|
Mohale M, Gundampati RK, Thallapuranam S, Heyes CD. Site-specific labeling and functional efficiencies of human fibroblast growth Factor-1 with a range of fluorescent dyes in the flexible N-Terminal region and a rigid β-turn region. Anal Biochem 2021; 640:114524. [PMID: 34933004 DOI: 10.1016/j.ab.2021.114524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 12/08/2021] [Indexed: 11/01/2022]
Abstract
Human fibroblast growth factor 1 (hFGF1) binding to its receptor and heparin play critical roles in cell proliferation, angiogenesis and wound healing but is also implicated in cancer. Fluorescence imaging is a powerful approach to study such protein interactions, but it is not always obvious if the site chosen will be efficiently labeled, often relying on trial-and-error. To provide a more systematic approach towards an efficient site-specific labeling strategy, we labeled two structurally distinct regions of the protein - the flexible N-terminus and a rigid loop. Several dyes were chosen to cover the visible region and to investigate how the structure of the dye affects the labeling efficiency. Flexibility in either the protein labeling site or the dye structure was found to result in high labeling efficiency, but flexibility in both resulted in a significant decrease in labeling efficiency. Conversely, too much rigidity in both can result in dye-protein interactions that can aggregate the protein. Importantly, site-specifically labeling hFGF1 in these regions maintained biological activity. These results could be applicable to other proteins by considering the flexibility of both the protein labeling site and the dye structure.
Collapse
Affiliation(s)
- Mamello Mohale
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Ravi Kumar Gundampati
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Suresh Thallapuranam
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA
| | - Colin D Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701, USA.
| |
Collapse
|
12
|
Abstract
Labeling of large RNAs with reporting entities, e.g., fluorophores, has significant impact on RNA studies in vitro and in vivo. Here, we describe a minimally invasive RNA labeling method featuring nucleotide and position selectivity, which solves the long-standing challenge of how to achieve accurate site-specific labeling of large RNAs with a least possible influence on folding and/or function. We use a custom-designed reactive DNA strand to hybridize to the RNA and transfer the alkyne group onto the targeted adenine or cytosine. Simultaneously, the 3'-terminus of RNA is converted to a dialdehyde moiety under the experimental condition applied. The incorporated functionalities at the internal and the 3'-terminal sites can then be conjugated with reporting entities via bioorthogonal chemistry. This method is particularly valuable for, but not limited to, single-molecule fluorescence applications. We demonstrate the method on an RNA construct of 275 nucleotides, the btuB riboswitch of Escherichia coli.
Collapse
Affiliation(s)
- Meng Zhao
- Department of Chemistry, University of Zurich, Zurich, Switzerland
- Department of Physics, University of Alberta, Edmonton, AB, Canada
| | - Richard Börner
- Department of Chemistry, University of Zurich, Zurich, Switzerland
- Laserinstitut Hochschule Mittweida, University of Applied Sciences Mittweida, Mittweida, Germany
| | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Zurich, Switzerland
| | - Eva Freisinger
- Department of Chemistry, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
13
|
Kuppa S, Pokhrel N, Corless E, Origanti S, Antony E. Generation of Fluorescent Versions of Saccharomyces cerevisiae RPA to Study the Conformational Dynamics of Its ssDNA-Binding Domains. Methods Mol Biol 2021; 2281:151-68. [PMID: 33847957 DOI: 10.1007/978-1-0716-1290-3_9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Replication protein A (RPA) is an essential single-stranded DNA (ssDNA)-binding protein that sequesters ssDNA and protects it from nucleolytic degradation. The RPA-ssDNA nucleoprotein acts as a hub to recruit over two dozen DNA metabolic enzymes onto ssDNA to coordinate DNA replication, repair, and recombination. RPA functions as a heterotrimer composed of RPA70, RPA32, and RPA14 subunits and has multiple DNA-binding and protein-interaction domains. Several of these domains are connected by disordered linkers allowing RPA to adopt a wide variety of conformations on ssDNA. Here we describe a fluorescence-based tool to monitor the dynamics of select DNA-binding domains of RPA. Noncanonical amino acids are utilized to site-specifically engineer fluorescent probes in Saccharomyces cerevisiae RPA heterologously expressed in BL21 (DE3) and its derivatives. A procedure to synthesize 4-azido-L-phenylalanine (4AZP), a noncanonical amino acid, is also described. Sites for fluorophore positioning that produce a measurable change in fluorescence upon binding to ssDNA are detailed. This fluorescence enhancement through noncanonical amino acid (FEncAA) approach can also be applied to other DNA-binding proteins to investigate the dynamics of protein-nucleic acid interactions.
Collapse
|
14
|
Wang Y, Shen Z, Wan Z, Liu W. Site-specific Labeling of B Cell Receptor and Soluble Immunoglobulin. Bio Protoc 2020; 10:e3767. [PMID: 33659425 DOI: 10.21769/bioprotoc.3767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/19/2020] [Accepted: 08/14/2020] [Indexed: 11/02/2022] Open
Abstract
B lymphocyte activation is regulated by its membrane-bound B cell receptors (BCRs) upon recognizing diverse antigens. It is hypothesized that antigen binding would trigger conformational changes within BCRs, followed by a series of downstream signaling activation. To measure the BCR conformational changes in live cells, a fluorescent site-specific labeling technique is preferred. Genetically encoded fluorescent tags visualize the location of the target proteins. However, these fluorescent proteins are large (~30 kDa) and would potentially perturb the conformation of BCRs. Here, we describe the general procedures of utilizing short tag-based site-specific labeling methodologies combining with fluorescence resonance energy transfer (FRET) assay to monitor the conformational changes within BCR extracellular domains upon antigen engagement.
Collapse
Affiliation(s)
- Yu Wang
- Ministry of Education Key Laboratory of Protein Sciences, Center for Life Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Institute for Immunology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhixun Shen
- Ministry of Education Key Laboratory of Protein Sciences, Center for Life Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Institute for Immunology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhengpeng Wan
- Ministry of Education Key Laboratory of Protein Sciences, Center for Life Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Institute for Immunology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,Department of Biological Engineering, Massachusetts Institutes of Technology, Cambridge, MA, USA
| | - Wanli Liu
- Ministry of Education Key Laboratory of Protein Sciences, Center for Life Sciences, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Institute for Immunology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| |
Collapse
|
15
|
Feng Y, Zhou Z, McDougald D, Meshaw RL, Vaidyanathan G, Zalutsky MR. Site-specific radioiodination of an anti-HER2 single domain antibody fragment with a residualizing prosthetic agent. Nucl Med Biol 2020; 92:171-183. [PMID: 32448731 DOI: 10.1016/j.nucmedbio.2020.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION As a consequence of their small size, high stability and high affinity, single domain antibody fragments (sdAbs) are appealing targeting vectors for radiopharmaceutical development. With sdAbs binding to internalizing receptors like HER2, residualizing prosthetic agents can enhance tumor retention of radioiodine, which until now has been done with random labeling approaches. Herein we evaluate a site-specific strategy utilizing a radioiodinated, residualizing maleimido moiety and the anti-HER2 sdAb 5F7 bearing a GGC tail for conjugation. METHODS Maleimidoethyl 3-(guanidinomethyl)-5-iodobenzoate ([131I]MEGMB) and its N-succinimidyl ester analogue, iso-[125I]SGMIB, were labeled by halodestannylation and conjugated with 5F7GGC and 5F7, respectively. Radiochemical purity, immunoreactivity and binding affinity were determined. Paired-label experiments directly compared iso-[125I]SGMIB-5F7 and [131I]MEGMIB-5F7GGC with regard to internalization/residualization and affinity on HER2-expressing SKOV-3 ovarian carcinoma cells as well as biodistribution and metabolite distribution in athymic mice with subcutaneous SKOV-3 xenografts. RESULTS [131I]MEGMIB-5F7GGC had an immunoreactivity of 81.3% and Kd = 0.94 ± 0.27 nM. Internalization assays demonstrated high intracellular trapping for both conjugates, For example, at 1 h, intracellular retention was 50.30 ± 3.36% for [131I]MEGMIB-5F7GGC and 55.95 ± 3.27% for iso-[125I]SGMIB-5F7, while higher retention was seen for iso-[125I]SGMIB-5F7 at later time points. Peak tumor uptake was similar for both conjugates (8.35 ± 2.66%ID/g and 8.43 ± 2.84%ID/g for iso-[125I]SGMIB-5F7 and [131I]MEGMIB-5F7GGC at 1 h, respectively); however, more rapid normal tissue clearance was seen for [131I]MEGMIB-5F7GGC, with a 2-fold higher tumor-to-kidney ratio and a 3-fold higher tumor-to-liver ratio compared with co-injected iso-[125I]SGMIB-5F7. Consisted with this, generation of labeled catabolites in the kidneys was higher for [131I]MEGMIB-5F7GGC. CONCLUSION [131I]MEGMIB-5F7GGC offers similar tumor targeting as iso-[125I]SGMIB-5F7 but with generally lower normal tissue uptake. ADVANCES IN KNOWLEDGE AND IMPLICATION FOR PATIENT CARE The site specific nature of the [131I]MEGMIB reagent may facilitate clinical translation, particularly for sdAb with compromised affinity after random labeling.
Collapse
Affiliation(s)
- Yutian Feng
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Zhengyuan Zhou
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Darryl McDougald
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Rebecca L Meshaw
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | | | - Michael R Zalutsky
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
| |
Collapse
|
16
|
Saleh AM, Wilding KM, Calve S, Bundy BC, Kinzer-Ursem TL. Non-canonical amino acid labeling in proteomics and biotechnology. J Biol Eng 2019; 13:43. [PMID: 31139251 PMCID: PMC6529998 DOI: 10.1186/s13036-019-0166-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 04/11/2019] [Indexed: 02/03/2023] Open
Abstract
Metabolic labeling of proteins with non-canonical amino acids (ncAAs) provides unique bioorthogonal chemical groups during de novo synthesis by taking advantage of both endogenous and heterologous protein synthesis machineries. Labeled proteins can then be selectively conjugated to fluorophores, affinity reagents, peptides, polymers, nanoparticles or surfaces for a wide variety of downstream applications in proteomics and biotechnology. In this review, we focus on techniques in which proteins are residue- and site-specifically labeled with ncAAs containing bioorthogonal handles. These ncAA-labeled proteins are: readily enriched from cells and tissues for identification via mass spectrometry-based proteomic analysis; selectively purified for downstream biotechnology applications; or labeled with fluorophores for in situ analysis. To facilitate the wider use of these techniques, we provide decision trees to help guide the design of future experiments. It is expected that the use of ncAA labeling will continue to expand into new application areas where spatial and temporal analysis of proteome dynamics and engineering new chemistries and new function into proteins are desired.
Collapse
Affiliation(s)
- Aya M. Saleh
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN USA
| | - Kristen M. Wilding
- Department of Chemical Engineering, Brigham Young University, Provo, UT USA
| | - Sarah Calve
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN USA
| | - Bradley C. Bundy
- Department of Chemical Engineering, Brigham Young University, Provo, UT USA
| | | |
Collapse
|
17
|
Abstract
Structurally, butelase 1 is a cysteine protease of the asparaginyl endoprotease (AEP) family, but functionally, it displays intense Asn/Asp-specific (Asx) ligase activity and is virtually devoid of protease activity. Butelase 1 recognizes specifically a C-terminal Asx-containing tripeptide motif, Asx-His-Val, to form an Asx-Xaa peptide bond (Xaa = any amino acid), either intramolecularly or intermolecularly, resulting in cyclic peptides or site-specific modified peptides/proteins, respectively. Our work in the past 4 years has validated that butelase 1 is a potent and versatile tool for peptide and protein modification. Here we describe our protocols using butelase 1 for efficient and site-specific peptide and protein ligation, N-terminal labeling, preparation of thioesters, and bioconjugation of dendrimers. Additionally, we provide an example using butelase 1 for protein cyclization in combination with genetic code expansion in order to incorporate unnatural building blocks.
Collapse
Affiliation(s)
- Xinya Hemu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xiaohong Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Xiaobao Bi
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
| |
Collapse
|
18
|
Wang HH, Tsourkas A. Site-Specific C-Terminal Labeling of Recombinant Proteins with Proximity-Based Sortase-Mediated Ligation (PBSL). Methods Mol Biol 2019; 2012:15-28. [PMID: 31161501 DOI: 10.1007/978-1-4939-9546-2_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
S. aureus sortase A (SrtA), a calcium-dependent transpeptidase, is frequently employed to site-specifically label the C-terminus of recombinant proteins bearing an LPXTG SrtA recognition motif. Unfortunately, SrtA suffers from low turnover rates, resulting in poor ligation efficiencies even with optimized reaction conditions. In this chapter, we describe proximity-based sortase-mediated ligation (PBSL), which uses the SpyTag-SpyCatcher peptide-protein pair to link SrtA to target proteins and dramatically improves reaction rate and ligation efficiency.
Collapse
Affiliation(s)
- Hejia Henry Wang
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew Tsourkas
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
19
|
Abstract
Super-resolution fluorescence microscopy methods are increasingly applied to study the structure of biological molecules within their natural context or at biomaterial interfaces. We here provide a protocol for Single-molecule High-Resolution Imaging with Photobleaching (SHRImP) that can be used to obtain information about the conformation of large proteins or other macromolecules at the single-molecule level. This procedure requires site-specific protein labeling with fluorescent dyes, immobilization and sample preparation, optimization of imaging buffer composition and microscope settings, and acquisition of short time-lapse movies that capture the stepwise bleaching behavior of individual molecules. We then describe a method for reliably determining the relative positions of labels from bleaching movies using the free image processing package Fiji (ImageJ) with the help of auxiliary macros that are provided as Supplementary Material. The presented approach allows for measuring intramolecular distance distributions in the range of a few to hundreds of nanometers and can be applied to a wide variety of biological systems.
Collapse
|
20
|
Le MT, Brown RE, Simon AE, Dayie TK. In vivo, large-scale preparation of uniformly (15)N- and site-specifically (13)C-labeled homogeneous, recombinant RNA for NMR studies. Methods Enzymol 2016; 565:495-535. [PMID: 26577743 DOI: 10.1016/bs.mie.2015.07.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Knowledge of how ribonucleic acid (RNA) structures fold to form intricate, three-dimensional structures has provided fundamental insights into understanding the biological functions of RNA. Nuclear magnetic resonance (NMR) spectroscopy is a particularly useful high-resolution technique to investigate the dynamic structure of RNA. Effective study of RNA by NMR requires enrichment with isotopes of (13)C or (15)N or both. Here, we present a method to produce milligram quantities of uniformly (15)N- and site-specifically (13)C-labeled RNAs using wild-type K12 and mutant tktA Escherichia coli in combination with a tRNA-scaffold approach. The method includes a double selection protocol to obtain an E. coli clone with consistently high expression of the recombinant tRNA-scaffold. We also present protocols for the purification of the tRNA-scaffold from a total cellular RNA extract and the excision of the RNA of interest from the tRNA-scaffold using DNAzymes. Finally, we showcase NMR applications to demonstrate the benefit of using in vivo site-specifically (13)C-labeled RNA.
Collapse
Affiliation(s)
- My T Le
- Department of Chemistry and Biochemistry,Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland, USA
| | - Rachel E Brown
- Department of Chemistry and Biochemistry, Department of Cellular Biology and Molecular Genetics, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland, USA
| | - Anne E Simon
- Department of Chemistry and Biochemistry, Department of Cellular Biology and Molecular Genetics, Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland, USA
| | - T Kwaku Dayie
- Department of Chemistry and Biochemistry,Center for Biomolecular Structure and Organization, University of Maryland, College Park, Maryland, USA.
| |
Collapse
|
21
|
Alvarado LJ, Longhini AP, LeBlanc RM, Chen B, Kreutz C, Dayie TK. Chemo-enzymatic synthesis of selectively ¹³C/¹⁵N-labeled RNA for NMR structural and dynamics studies. Methods Enzymol 2015; 549:133-62. [PMID: 25432748 DOI: 10.1016/b978-0-12-801122-5.00007-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
RNAs are an important class of cellular regulatory elements, and they are well characterized by X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy in their folded or bound states. However, the apo or unfolded states are more difficult to characterize by either method. Particularly, effective NMR spectroscopy studies of RNAs in the past were hampered by chemical shift overlap of resonances and associated rapid signal loss due to line broadening for RNAs larger than the median size found in the PDB (~25 nt); most functional riboswitches are bigger than this median size. Incorporation of selective site-specific (13)C/(15)N-labeled nucleotides into RNAs promises to overcome this NMR size limitation. Unlike previous isotopic enrichment methods such as phosphoramidite, de novo, uniform-labeling, and selective-biomass approaches, this newer chemical-enzymatic selective method presents a number of advantages for producing labeled nucleotides over these other methods. For example, total chemical synthesis of nucleotides, followed by solid-phase synthesis of RNA using phosphoramidite chemistry, while versatile in incorporating isotope labels into RNA at any desired position, faces problems of low yields (<10%) that drop precipitously for oligonucleotides larger than 50 nt. The alternative method of de novo pyrimidine biosynthesis of NTPs is also a robust technique, with modest yields of up to 45%, but it comes at the cost of using 16 enzymes, expensive substrates, and difficulty in making some needed labeling patterns such as selective labeling of the ribose C1' and C5' and the pyrimidine nucleobase C2, C4, C5, or C6. Biomass-produced, uniformly or selectively labeled NTPs offer a third method, but suffer from low overall yield per labeled input metabolite and isotopic scrambling with only modest suppression of (13)C-(13)C couplings. In contrast to these four methods, our current chemo-enzymatic approach overcomes most of these shortcomings and allows for the synthesis of gram quantities of nucleotides with >80% yields while using a limited number of enzymes, six at most. The unavailability of selectively labeled ribose and base precursors had prevented the effective use of this versatile method until now. Recently, we combined an improved organic synthetic approach that selectively places (13)C/(15)N labels in the pyrimidine nucleobase (either (15)N1, (15)N3, (13)C2, (13)C4, (13)C5, or (13)C6 or any combination) with a very efficient enzymatic method to couple ribose with uracil to produce previously unattainable labeling patterns (Alvarado et al., 2014). Herein we provide detailed steps of both our chemo-enzymatic synthesis of custom nucleotides and their incorporation into RNAs with sizes ranging from 29 to 155 nt and showcase the dramatic improvement in spectral quality of reduced crowding and narrow linewidths. Applications of this selective labeling technology should prove valuable in overcoming two major obstacles, chemical shift overlap of resonances and associated rapid signal loss due to line broadening, that have impeded studying the structure and dynamics of large RNAs such as full-length riboswitches larger than the ~25 nt median size of RNA NMR structures found in the PDB.
Collapse
Affiliation(s)
- Luigi J Alvarado
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Andrew P Longhini
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Regan M LeBlanc
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Bin Chen
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), University of Innsbruck, Innrain, Innsbruck, Austria
| | - T Kwaku Dayie
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure & Organization, University of Maryland, College Park, Maryland, USA.
| |
Collapse
|