1
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Joest EF, Tampé R. Design principles for engineering light-controlled antibodies. Trends Biotechnol 2023; 41:1501-1517. [PMID: 37507295 DOI: 10.1016/j.tibtech.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 07/30/2023]
Abstract
Engineered antibodies are essential tools for research and advanced pharmacy. In the development of therapeutics, antibodies are excellent candidates as they offer both target recognition and modulation. Thanks to the latest advances in biotechnology, light-activated antibody fragments can be constructed to control spontaneous antigen interaction with high spatiotemporal precision. To implement conditional antigen binding, several optogenetic and optochemical engineering concepts have recently been developed. Here, we highlight the various strategies and discuss the features of opto-conditional antibodies. Each concept offers intrinsic advantages beneficial to different applications. In summary, the novel design approaches constitute a complementary toolset to promote current and upcoming antibody technologies with ultimate precision.
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Affiliation(s)
- Eike F Joest
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt a.M., Germany.
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt a.M., Germany.
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2
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Meineke B, Heimgärtner J, Caridha R, Block MF, Kimler KJ, Pires MF, Landreh M, Elsässer SJ. Dual stop codon suppression in mammalian cells with genomically integrated genetic code expansion machinery. CELL REPORTS METHODS 2023; 3:100626. [PMID: 37935196 PMCID: PMC10694491 DOI: 10.1016/j.crmeth.2023.100626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/22/2023] [Accepted: 10/12/2023] [Indexed: 11/09/2023]
Abstract
Stop codon suppression using dedicated tRNA/aminoacyl-tRNA synthetase (aaRS) pairs allows for genetically encoded, site-specific incorporation of non-canonical amino acids (ncAAs) as chemical handles for protein labeling and modification. Here, we demonstrate that piggyBac-mediated genomic integration of archaeal pyrrolysine tRNA (tRNAPyl)/pyrrolysyl-tRNA synthetase (PylRS) or bacterial tRNA/aaRS pairs, using a modular plasmid design with multi-copy tRNA arrays, allows for homogeneous and efficient genetically encoded ncAA incorporation in diverse mammalian cell lines. We assess opportunities and limitations of using ncAAs for fluorescent labeling applications in stable cell lines. We explore suppression of ochre and opal stop codons and finally incorporate two distinct ncAAs with mutually orthogonal click chemistries for site-specific, dual-fluorophore labeling of a cell surface receptor on live mammalian cells.
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Affiliation(s)
- Birthe Meineke
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, 17165 Stockholm, Sweden.
| | - Johannes Heimgärtner
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Rozina Caridha
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Matthias F Block
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden
| | - Kyle J Kimler
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden
| | - Maria F Pires
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Science for Life Laboratory, Karolinska Institutet, 17165 Stockholm, Sweden
| | - Simon J Elsässer
- Science for Life Laboratory, Karolinska Institutet, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, 17165 Stockholm, Sweden; Ming Wai Lau Centre for Reparative Medicine, Stockholm Node, Karolinska Institutet, 17165 Stockholm, Sweden.
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3
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Puzzo F, Zhang C, Powell Gray B, Zhang F, Sullenger BA, Kay MA. Aptamer-programmable adeno-associated viral vectors as a novel platform for cell-specific gene transfer. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 31:383-397. [PMID: 36817723 PMCID: PMC9929486 DOI: 10.1016/j.omtn.2023.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Adeno-associated viruses (AAVs) are commonly used for in vivo gene therapy. Nevertheless, the wide tropism that characterizes these vectors limits specific targeting to a particular cell type or tissue. Here, we developed new chemically modified AAV vectors (Nε-AAVs) displaying a single site substitution on the capsid surface for post-production vector engineering through biorthogonal copper-free click chemistry. We were able to identify AAV vectors that would tolerate the unnatural amino acid substitution on the capsid without disrupting their packaging efficiency. We functionalized the Nε-AAVs through conjugation with DNA (AS1411) or RNA (E3) aptamers or with a folic acid moiety (FA). E3-, AS1411-, and FA-AAVs showed on average a 3- to 9-fold increase in transduction compared with their non-conjugated counterparts in different cancer cell lines. Using specific competitors, we established ligand-specific transduction. In vivo studies confirmed the selective uptake of FA-AAV and AS1411-AAV without off-target transduction in peripheral organs. Overall, the high versatility of these novel Nε-AAVs might pave the way to tailoring gene therapy vectors toward specific types of cells both for ex vivo and in vivo applications.
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Affiliation(s)
- Francesco Puzzo
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Chuanling Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Bethany Powell Gray
- Department of Surgery, Duke University School of Medicine, Durham, NC 27705, USA
| | - Feijie Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Bruce A. Sullenger
- Department of Surgery, Duke University School of Medicine, Durham, NC 27705, USA
| | - Mark A. Kay
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
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4
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Meineke B, Elsässer SJ. Generation of Amber Suppression Cell Lines Using CRISPR-Cas9. Methods Mol Biol 2023; 2676:169-180. [PMID: 37277632 DOI: 10.1007/978-1-0716-3251-2_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Genetic code expansion via amber suppression allows cotranslational, site-specific introduction of nonnatural chemical groups into proteins in the living cell. The archaeal pyrrolysine-tRNA/pyrrolysine-tRNA synthetase (PylT/RS) pair from Methanosarcina mazei (Mma) has been established for incorporation of a wide range of noncanonical amino acids (ncAAs) in mammalian cells. Once integrated in an engineered protein, ncAAs allow for simple click-chemistry derivatization, photo-cage control of enzyme activity, and site-specific placement of posttranslational modifications. We previously described a modular amber suppression plasmid system for generating stable cell lines via piggyBac transposition in a range of mammalian cells. Here we detail a general protocol for the generation of CRISPR-Cas9 knock-in cell lines using the same plasmid system. The knock-in strategy relies on CRISPR-Cas9-induced double-strand breaks (DSBs) and nonhomologous end joining (NHEJ) repair to target the PylT/RS expression cassette to the AAVS1 safe harbor locus in human cells. MmaPylRS expression from this single locus is sufficient for efficient amber suppression when the cells are subsequently transfected transiently with a PylT/gene of interest plasmid.
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Affiliation(s)
- Birthe Meineke
- Laboratory of Synthetic and Systems Biology, Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Solna, Stockholm, Sweden.
| | - Simon J Elsässer
- Laboratory of Synthetic and Systems Biology, Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Solna, Stockholm, Sweden
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5
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Palomar-Siles M, Heldin A, Zhang M, Strandgren C, Yurevych V, van Dinter JT, Engels SAG, Hofman DA, Öhlin S, Meineke B, Bykov VJN, van Heesch S, Wiman KG. Translational readthrough of nonsense mutant TP53 by mRNA incorporation of 5-Fluorouridine. Cell Death Dis 2022; 13:997. [PMID: 36433934 PMCID: PMC9700717 DOI: 10.1038/s41419-022-05431-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/08/2022] [Accepted: 11/10/2022] [Indexed: 11/27/2022]
Abstract
TP53 nonsense mutations in cancer produce truncated inactive p53 protein. We show that 5-FU metabolite 5-Fluorouridine (FUr) induces full-length p53 in human tumor cells carrying R213X nonsense mutant TP53. Ribosome profiling visualized translational readthrough at the R213X premature stop codon and demonstrated that FUr-induced readthrough is less permissive for canonical stop codon readthrough compared to aminoglycoside G418. FUr is incorporated into mRNA and can potentially base-pair with guanine, allowing insertion of Arg tRNA at the TP53 R213X UGA premature stop codon and translation of full-length wild-type p53. We confirmed that full-length p53 rescued by FUr triggers tumor cell death by apoptosis. FUr also restored full-length p53 in TP53 R213X mutant human tumor xenografts in vivo. Thus, we demonstrate a novel strategy for therapeutic rescue of nonsense mutant TP53 and suggest that FUr should be explored for treatment of patients with TP53 nonsense mutant tumors.
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Affiliation(s)
- Mireia Palomar-Siles
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Angelos Heldin
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Meiqiongzi Zhang
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Charlotte Strandgren
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Viktor Yurevych
- grid.487647.ePrincess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Jip T. van Dinter
- grid.487647.ePrincess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Sem A. G. Engels
- grid.487647.ePrincess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Damon A. Hofman
- grid.487647.ePrincess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Susanne Öhlin
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Birthe Meineke
- grid.4714.60000 0004 1937 0626Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Vladimir J. N. Bykov
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Sebastiaan van Heesch
- grid.487647.ePrincess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Klas G. Wiman
- grid.4714.60000 0004 1937 0626Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
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6
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van Husen LS, Katsori AM, Meineke B, Tjernberg LO, Schedin-Weiss S, Elsässer SJ. Engineered Human Induced Pluripotent Cells Enable Genetic Code Expansion in Brain Organoids. Chembiochem 2021; 22:3208-3213. [PMID: 34431592 PMCID: PMC9290828 DOI: 10.1002/cbic.202100399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 08/24/2021] [Indexed: 11/07/2022]
Abstract
Human induced pluripotent stem cell (hiPSC) technology has revolutionized studies on human biology. A wide range of cell types and tissue models can be derived from hiPSCs to study complex human diseases. Here, we use PiggyBac-mediated transgenesis to engineer hiPSCs with an expanded genetic code. We demonstrate that genomic integration of expression cassettes for a pyrrolysyl-tRNA synthetase (PylRS), pyrrolysyl-tRNA (PylT) and the target protein of interest enables site-specific incorporation of a non-canonical amino acid (ncAA) in response to an amber stop codon. Neural stem cells, neurons and brain organoids derived from the engineered hiPSCs continue to express the amber suppression machinery and produce ncAA-bearing reporter. The incorporated ncAA can serve as a minimal bioorthogonal handle for further modifications by labeling with fluorescent dyes. Site-directed ncAA mutagenesis will open a wide range of applications to probe and manipulate proteins in brain organoids and other hiPSC-derived cell types and complex tissue models.
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Affiliation(s)
- Lea S van Husen
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165, Stockholm, Sweden.,Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, 17164, Stockholm, Sweden
| | - Anna-Maria Katsori
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165, Stockholm, Sweden
| | - Birthe Meineke
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165, Stockholm, Sweden
| | - Lars O Tjernberg
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, 17164, Stockholm, Sweden
| | - Sophia Schedin-Weiss
- Center for Alzheimer Research, Division of Neurogeriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, 17164, Stockholm, Sweden
| | - Simon J Elsässer
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17165, Stockholm, Sweden
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7
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Hao R, Ma K, Ru Y, Li D, Song G, Lu B, Liu H, Li Y, Zhang J, Wu C, Zhang G, Hu H, Luo J, Zheng H. Amber codon is genetically unstable in generation of premature termination codon (PTC)-harbouring Foot-and-mouth disease virus (FMDV) via genetic code expansion. RNA Biol 2021; 18:2330-2341. [PMID: 33849391 DOI: 10.1080/15476286.2021.1907055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The foot-and-mouth disease virus (FMDV) is the causative agent of FMD, a highly infectious and devastating viral disease of domestic and wild cloven-hoofed animals. FMD affects livestock and animal products' national and international trade, causing severe economic losses and social consequences. Currently, inactivated vaccines play a vital role in FMD control, but they have several limitations. The genetic code expansion technology provides powerful strategies for generating premature termination codon (PTC)-harbouring virus as a live but replication-incompetent viral vaccine. However, this technology has not been explored for the design and development of new FMD vaccines. In this study, we first expanded the genetic code of the FMDV genome via a transgenic cell line containing an orthogonal translation machinery. We demonstrated that the transgenic cells stably integrated the orthogonal pyltRNA/pylRS pair into the genome and enabled efficient, homogeneous incorporation of unnatural amino acids into target proteins in mammalian cells. Next, we constructed 129 single-PTC FMDV mutants and four dual-PTC FMDV mutants after considering the tolerance, location, and potential functions of those mutated sites. Amber stop codons individually substituted the selected amino acid codons in four viral proteins (3D, L, VP1, and VP4) of FMDV. We successfully rescued PTC-FMDV mutants, but the amber codon unexpectedly showed a highly degree of mutation rate during PTC-FMDV packaging and replication. Our findings highlight that the genetic code expansion technology for the generation of PTC-FMD vaccines needs to be further improved and that the genetic stability of amber codons during the packaging and replication of FMDV is a concern.
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Affiliation(s)
- Rongzeng Hao
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Kun Ma
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yi Ru
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Dan Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Gaoyuan Song
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Bingzhou Lu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Huanan Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yajun Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Jiaoyan Zhang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Chunping Wu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Guicai Zhang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Haitao Hu
- Department of Microbiology and Immunology, Sealy Center for Vaccine Development and Institute for Human Infections and Immunity, University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | - Jianxun Luo
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Haixue Zheng
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, OIE/National Foot and Mouth Diseases Reference Laboratory, Chinese Academy of Agricultural Sciences, Lanzhou, China
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8
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Lafranchi L, Schlesinger D, Kimler KJ, Elsässer SJ. Universal Single-Residue Terminal Labels for Fluorescent Live Cell Imaging of Microproteins. J Am Chem Soc 2020; 142:20080-20087. [PMID: 33175524 DOI: 10.1021/jacs.0c09574] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Genetically encoded fluorescent tags for visualization of proteins in living cells add six to several hundred amino acids to the protein of interest. While suitable for most proteins, common tags easily match and exceed the size of microproteins of 60 amino acids or less. The added molecular weight and structure of such fluorescent tag may thus significantly affect in vivo biophysical and biochemical properties of microproteins. Here, we develop single-residue terminal labeling (STELLA) tags that introduce a single noncanonical amino acid either at the N- or C-terminus of a protein or microprotein of interest for subsequent specific fluorescent labeling. Efficient terminal noncanonical amino acid mutagenesis is achieved using a precursor tag that is tracelessly cleaved. Subsequent selective bioorthogonal reaction with a cell-permeable organic dye enables live cell imaging of microproteins with minimal perturbation of their native sequence. The use of terminal residues for labeling provides a universally applicable and easily scalable strategy, which avoids alteration of the core sequence of the microprotein.
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Affiliation(s)
- Lorenzo Lafranchi
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Stockholm, 17165, Sweden.,Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Dörte Schlesinger
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Stockholm, 17165, Sweden.,Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Kyle J Kimler
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Stockholm, 17165, Sweden.,Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm, 17165, Sweden
| | - Simon J Elsässer
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Division of Genome Biology, Karolinska Institutet, Stockholm, 17165, Sweden.,Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institutet, Stockholm, 17165, Sweden
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9
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An embryonic stem cell-specific heterochromatin state promotes core histone exchange in the absence of DNA accessibility. Nat Commun 2020; 11:5095. [PMID: 33037201 PMCID: PMC7547087 DOI: 10.1038/s41467-020-18863-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 09/14/2020] [Indexed: 12/17/2022] Open
Abstract
Nucleosome turnover concomitant with incorporation of the replication-independent histone variant H3.3 is a hallmark of regulatory regions in the animal genome. Nucleosome turnover is known to be universally linked to DNA accessibility and histone acetylation. In mouse embryonic stem cells, H3.3 is also highly enriched at interstitial heterochromatin, most prominently at intracisternal A-particle endogenous retroviral elements. Interstitial heterochromatin is established over confined domains by the TRIM28-KAP1/SETDB1 corepressor complex and has stereotypical features of repressive chromatin, such as H3K9me3 and recruitment of all HP1 isoforms. Here, we demonstrate that fast histone turnover and H3.3 incorporation is compatible with these hallmarks of heterochromatin. Further, we find that Smarcad1 chromatin remodeler evicts nucleosomes generating accessible DNA. Free DNA is repackaged via DAXX-mediated nucleosome assembly with histone variant H3.3 in this dynamic heterochromatin state. Loss of H3.3 in mouse embryonic stem cells elicits a highly specific opening of interstitial heterochromatin with minimal effects on other silent or active regions of the genome. Nucleosome turnover concomitant with incorporation of the histone variant H3.3 is a hallmark of regulatory regions in the animal genome. Here, the authors demonstrate that fast histone turnover and H3.3 incorporation defines a dynamic heterochromatin state in pluripotent stem cells.
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10
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Meineke B, Heimgärtner J, Lafranchi L, Elsässer SJ. Methanomethylophilus alvus Mx1201 Provides Basis for Mutual Orthogonal Pyrrolysyl tRNA/Aminoacyl-tRNA Synthetase Pairs in Mammalian Cells. ACS Chem Biol 2018; 13:3087-3096. [PMID: 30260624 PMCID: PMC6243396 DOI: 10.1021/acschembio.8b00571] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Genetic
code expansion via stop codon suppression
is a powerful technique for engineering proteins in mammalian cells
with site-specifically encoded noncanonical amino acids (ncAAs). Current
methods rely on very few available tRNA/aminoacyl-tRNA synthetase
pairs orthogonal in mammalian cells, the pyrrolysyl tRNA/aminoacyl-tRNA
synthetase pair from Methanosarcina mazei (Mma PylRS/PylT) being the most active and versatile to date.
We found a pyrrolysyl tRNA/aminoacyl-tRNA synthetase pair from the
human gut archaeon Methanomethylophilus alvus Mx1201 (Mx1201 PylRS/PylT) to be active and orthogonal in mammalian cells. We show
that this PylRS enzyme can be engineered to expand its ncAA substrate
spectrum. We find that due to the large evolutionary distance of the
two pairs, Mx1201 PylRS/PylT is partially orthogonal
to Mma PylRS/PylT. Through rational mutation of Mx1201 PylT, we abolish its noncognate interaction with Mma PylRS, creating two mutually orthogonal PylRS/PylT pairs.
Combined in the same cell, we show that the two pairs can site-selectively
introduce two different ncAAs in response to two distinct stop codons.
Our work expands the repertoire of mutually orthogonal tools for genetic
code expansion in mammalian cells and provides the basis for advanced in vivo protein engineering applications for cell biology
and protein production.
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Affiliation(s)
- Birthe Meineke
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Johannes Heimgärtner
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lorenzo Lafranchi
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Simon J. Elsässer
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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