1
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Ishida S, Ngo PHT, Gundlach A, Ellington A. Engineering Ribosomal Machinery for Noncanonical Amino Acid Incorporation. Chem Rev 2024; 124:7712-7730. [PMID: 38829723 DOI: 10.1021/acs.chemrev.3c00912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
The introduction of noncanonical amino acids into proteins has enabled researchers to modify fundamental physicochemical and functional properties of proteins. While the alteration of the genetic code, via the introduction of orthogonal aminoacyl-tRNA synthetase:tRNA pairs, has driven many of these efforts, the various components involved in the process of translation are important for the development of new genetic codes. In this review, we will focus on recent advances in engineering ribosomal machinery for noncanonical amino acid incorporation and genetic code modification. The engineering of the ribosome itself will be considered, as well as the many factors that interact closely with the ribosome, including both tRNAs and accessory factors, such as the all-important EF-Tu. Given the success of genome re-engineering efforts, future paths for radical alterations of the genetic code will require more expansive alterations in the translation machinery.
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Affiliation(s)
- Satoshi Ishida
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, United States
| | - Phuoc H T Ngo
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, United States
| | - Arno Gundlach
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, United States
| | - Andrew Ellington
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, United States
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2
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Sigal M, Matsumoto S, Beattie A, Katoh T, Suga H. Engineering tRNAs for the Ribosomal Translation of Non-proteinogenic Monomers. Chem Rev 2024; 124:6444-6500. [PMID: 38688034 PMCID: PMC11122139 DOI: 10.1021/acs.chemrev.3c00894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/21/2024] [Accepted: 04/10/2024] [Indexed: 05/02/2024]
Abstract
Ribosome-dependent protein biosynthesis is an essential cellular process mediated by transfer RNAs (tRNAs). Generally, ribosomally synthesized proteins are limited to the 22 proteinogenic amino acids (pAAs: 20 l-α-amino acids present in the standard genetic code, selenocysteine, and pyrrolysine). However, engineering tRNAs for the ribosomal incorporation of non-proteinogenic monomers (npMs) as building blocks has led to the creation of unique polypeptides with broad applications in cellular biology, material science, spectroscopy, and pharmaceuticals. Ribosomal polymerization of these engineered polypeptides presents a variety of challenges for biochemists, as translation efficiency and fidelity is often insufficient when employing npMs. In this Review, we will focus on the methodologies for engineering tRNAs to overcome these issues and explore recent advances both in vitro and in vivo. These efforts include increasing orthogonality, recruiting essential translation factors, and creation of expanded genetic codes. After our review on the biochemical optimizations of tRNAs, we provide examples of their use in genetic code manipulation, with a focus on the in vitro discovery of bioactive macrocyclic peptides containing npMs. Finally, an analysis of the current state of tRNA engineering is presented, along with existing challenges and future perspectives for the field.
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Affiliation(s)
- Maxwell Sigal
- Department of Chemistry,
Graduate School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Satomi Matsumoto
- Department of Chemistry,
Graduate School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Adam Beattie
- Department of Chemistry,
Graduate School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takayuki Katoh
- Department of Chemistry,
Graduate School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroaki Suga
- Department of Chemistry,
Graduate School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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3
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Kerestesy GN, Dods KK, McFeely CAL, Hartman MCT. Continuous Fluorescence Assay for In Vitro Translation Compatible with Noncanonical Amino Acids. ACS Synth Biol 2024; 13:119-128. [PMID: 38194520 PMCID: PMC11165968 DOI: 10.1021/acssynbio.3c00353] [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] [Indexed: 01/11/2024]
Abstract
The tolerance of the translation apparatus toward noncanonical amino acids (ncAAs) has enabled the creation of diverse natural-product-like peptide libraries using mRNA display for use in drug discovery. Typical experiments testing for ribosomal ncAA incorporation involve radioactive end point assays to measure yield alongside mass spectrometry experiments to validate incorporation. These end point assays require significant postexperimental manipulation for analysis and prevent higher throughput analysis and optimization experiments. Continuous assays for in vitro translation involve the synthesis of fluorescent proteins which require the full complement of canonical AAs for function and are therefore of limited utility for testing of ncAAs. Here, we describe a new, continuous fluorescence assay for in vitro translation based on detection of a short peptide tag using an affinity clamp protein, which exhibits changes in its fluorescent properties upon binding. Using this assay in a 384-well format, we were able to validate the incorporation of a variety of ncAAs and also quickly test for the codon reading specificities of a variety of Escherichia coli tRNAs. This assay enables rapid assessment of ncAAs and optimization of translation components and is therefore expected to advance the engineering of the translation apparatus for drug discovery and synthetic biology.
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Affiliation(s)
- Gianna N Kerestesy
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23220 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, 23298-0037 Virginia, United States
| | - Kara K Dods
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23220 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, 23298-0037 Virginia, United States
| | - Clinton A L McFeely
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23220 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, 23298-0037 Virginia, United States
| | - Matthew C T Hartman
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23220 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, 23298-0037 Virginia, United States
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4
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Abrigo NA, Dods KK, Makovsky CA, Lohan S, Mitra K, Newcomb KM, Le A, Hartman MCT. Development of a Cyclic, Cell Penetrating Peptide Compatible with In Vitro Selection Strategies. ACS Chem Biol 2023; 18:746-755. [PMID: 36920103 PMCID: PMC11165944 DOI: 10.1021/acschembio.2c00680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
A key limitation for the development of peptides as therapeutics is their lack of cell permeability. Recent work has shown that short, arginine-rich macrocyclic peptides containing hydrophobic amino acids are able to penetrate cells and reach the cytosol. Here, we have developed a new strategy for developing cyclic cell penetrating peptides (CPPs) that shifts some of the hydrophobic character to the peptide cyclization linker, allowing us to do a linker screen to find cyclic CPPs with improved cellular uptake. We demonstrate that both hydrophobicity and position of the alkylation points on the linker affect uptake of macrocyclic cell penetrating peptides (CPPs). Our best peptide, 4i, is on par with or better than prototypical CPPs Arg9 (R9) and CPP12 under assays measuring total cellular uptake and cytosolic delivery. 4i was also able to carry a peptide previously discovered from an in vitro selection, 8.6, and a cytotoxic peptide into the cytosol. A bicyclic variant of 4i showed even better cytosolic entry than 4i, highlighting the plasticity of this class of peptides toward modifications. Since our CPPs are cyclized via their side chains (as opposed to head-to-tail cyclization), they are compatible with powerful technologies for peptide ligand discovery including phage display and mRNA display. Access to diverse libraries with inherent cell permeability will afford the ability to find cell permeable hits to many challenging intracellular targets.
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Affiliation(s)
- Nicolas A Abrigo
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Kara K Dods
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Chelsea A Makovsky
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Sandeep Lohan
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Koushambi Mitra
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Kaylee M Newcomb
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Anthony Le
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
| | - Matthew C T Hartman
- Chemistry, Virginia Commonwealth University, 1001 W Main Street, Richmond, 23284 Virginia, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, 23219 Virginia, United States
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5
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McFeely CAL, Dods KK, Patel SS, Hartman MCT. Expansion of the genetic code through reassignment of redundant sense codons using fully modified tRNA. Nucleic Acids Res 2022; 50:11374-11386. [PMID: 36300637 PMCID: PMC9638912 DOI: 10.1093/nar/gkac846] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/09/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022] Open
Abstract
Breaking codon degeneracy for the introduction of non-canonical amino acids offers many opportunities in synthetic biology. Yet, despite the existence of 64 codons, the code has only been expanded to 25 amino acids in vitro. A limiting factor could be the over-reliance on synthetic tRNAs which lack the post-transcriptional modifications that improve translational fidelity. To determine whether modified, wild-type tRNA could improve sense codon reassignment, we developed a new fluorous method for tRNA capture and applied it to the isolation of roughly half of the Escherichia coli tRNA isoacceptors. We then performed codon competition experiments between the five captured wild-type leucyl-tRNAs and their synthetic counterparts, revealing a strong preference for wild-type tRNA in an in vitro translation system. Finally, we compared the ability of wild-type and synthetic leucyl-tRNA to break the degeneracy of the leucine codon box, showing that only captured wild-type tRNAs are discriminated with enough fidelity to accurately split the leucine codon box for the encoding of three separate amino acids. Wild-type tRNAs are therefore enabling reagents for maximizing the reassignment potential of the genetic code.
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Affiliation(s)
- Clinton A L McFeely
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Kara K Dods
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Shivam S Patel
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
| | - Matthew C T Hartman
- Department of Chemistry, Virginia Commonwealth University , Richmond, VA 23220 , USA
- Massey Cancer Center, Virginia Commonwealth University , Richmond, VA 23220 , USA
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6
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Shakya B, Joyner OG, Hartman MCT. Hyperaccurate Ribosomes for Improved Genetic Code Reprogramming. ACS Synth Biol 2022; 11:2193-2201. [PMID: 35549158 PMCID: PMC10100576 DOI: 10.1021/acssynbio.2c00150] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reprogramming of the genetic code through the introduction of noncanonical amino acids (ncAAs) has enabled exciting advances in synthetic biology and peptide drug discovery. Ribosomes that function with high efficiency and fidelity are necessary for all of these efforts, but for challenging ncAAs, the competing processes of near-cognate readthrough and peptidyl-tRNA dropoff can be issues. Here we uncover the surprising extent of these competing pathways in the PURE translation system using mRNAs encoding peptides with affinity tags at the N- and C-termini. We also show that hyperaccurate or error restrictive ribosomes with mutations in ribosomal protein S12 lead to significant improvements in yield and fidelity in the context of both canonical AAs and a challenging α,α-disubstituted ncAA. Hyperaccurate ribosomes also improve yields for quadruplet codon readthrough for a tRNA containing an expanded anticodon stem-loop, although they are not able to eliminate triplet codon reading by this tRNA. The impressive improvements in fidelity and the simplicity of introducing this mutation alongside other efforts to engineer the translation apparatus make hyperaccurate ribosomes an important advance for synthetic biology.
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Affiliation(s)
- Bipasana Shakya
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23220, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Olivia G. Joyner
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23220, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Matthew C. T. Hartman
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23220, United States
- Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23220, United States
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7
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Hartman MCT. Non-canonical Amino Acid Substrates of E. coli Aminoacyl-tRNA Synthetases. Chembiochem 2022; 23:e202100299. [PMID: 34416067 PMCID: PMC9651912 DOI: 10.1002/cbic.202100299] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/03/2021] [Indexed: 01/07/2023]
Abstract
In this comprehensive review, I focus on the twenty E. coli aminoacyl-tRNA synthetases and their ability to charge non-canonical amino acids (ncAAs) onto tRNAs. The promiscuity of these enzymes has been harnessed for diverse applications including understanding and engineering of protein function, creation of organisms with an expanded genetic code, and the synthesis of diverse peptide libraries for drug discovery. The review catalogues the structures of all known ncAA substrates for each of the 20 E. coli aminoacyl-tRNA synthetases, including ncAA substrates for engineered versions of these enzymes. Drawing from the structures in the list, I highlight trends and novel opportunities for further exploitation of these ncAAs in the engineering of protein function, synthetic biology, and in drug discovery.
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Affiliation(s)
- Matthew C T Hartman
- Department of Chemistry and Massey Cancer Center, Virginia Commonwealth University, 1001 W Main St., Richmond, VA 23220, USA
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8
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Incorporation of backbone modifications in mRNA-displayable peptides. Methods Enzymol 2021; 656:521-544. [PMID: 34325797 DOI: 10.1016/bs.mie.2021.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Here we comprehensively summarize the most recent efforts in our research team, aiming at installing N-methyl and azole backbones into peptides expressed in translation. The genetic code reprogramming using the Flexible In-vitro Translation system (FIT system) has proven to be the most reliable and versatile approach for ribosomally installing various exotic amino acids. However, it had been yet difficult in translating diverse kinds of multiple and consecutive sequences of N-methyl amino acids (MeAAs). We have recently reported that a semi-rational fine tuning of MeAA-tRNA affinities for EF-Tu by altering tRNA T-stem sequence achieves efficient delivery of MeAA-tRNAs to the ribosome. Indeed, this approach has made it possible to express N-methyl-peptides containing multiple MeAAs with a remarkably high fidelity. Another interesting backbone modification in peptides is azole moieties often found in natural products, but they are explicitly installed by post-translational modifying enzymes. We have recently devised a method to bypass such enzymatic processes where a bromovinyl group-containing amino acid is incorporated into the peptide by genetic code reprogramming and then chemically converted to an azole group via an intramolecular heterocyclization reaction. These methods will grant more drug-like properties to peptides than ordinary peptides in terms of protease resistance and cell membrane permeability. Particularly when they can be integrated with in vitro mRNA display, such as the RaPID system, the discovery of de novo bioactive peptides can be realized.
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9
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Adaligil E, Song A, Hallenbeck KK, Cunningham CN, Fairbrother WJ. Ribosomal Synthesis of Macrocyclic Peptides with β 2- and β 2,3-Homo-Amino Acids for the Development of Natural Product-Like Combinatorial Libraries. ACS Chem Biol 2021; 16:1011-1018. [PMID: 34008946 DOI: 10.1021/acschembio.1c00062] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The development of large, natural-product-like, combinatorial macrocyclic peptide libraries is essential in the quest to develop therapeutics for "undruggable" cellular targets. Herein we report the ribosomal synthesis of macrocyclic peptides containing one or more β2-homo-amino acids (β2haa) to enable their incorporation into mRNA display-based selection libraries. We confirmed the compatibility of 14 β2-homo-amino acids, (S)- and (R)-stereochemistry, for single incorporation into a macrocyclic peptide with low to high translation efficiency. Interestingly, N-methylation of the backbone amide of β2haa prevented the incorporation of this amino acid subclass by the ribosome. Additionally, we designed and incorporated several α,β-disubstituted β2,3-homo-amino acids (β2,3haa) with different R-groups on the α- and β-carbons of the same amino acid. Incorporation of these β2,3haa enables increased diversity in a single position of a macrocyclic peptide without significantly increasing the overall molecular weight, which is an important consideration for passive cell permeability. We also successfully incorporated multiple (S)-β2hAla into a single macrocycle with other non-proteinogenic amino acids, confirming that this class of β-amino acid is suitable for development of large scale macrocyclic peptide libraries.
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Affiliation(s)
- Emel Adaligil
- Department of Early Discovery Biochemistry, Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Aimin Song
- Department of Early Discovery Biochemistry, Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Kenneth K. Hallenbeck
- Department of Early Discovery Biochemistry, Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Christian N. Cunningham
- Department of Early Discovery Biochemistry, Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Wayne J. Fairbrother
- Department of Early Discovery Biochemistry, Genentech, 1 DNA Way, South San Francisco, California 94080, United States
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10
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Iskandar SE, Haberman VA, Bowers AA. Expanding the Chemical Diversity of Genetically Encoded Libraries. ACS COMBINATORIAL SCIENCE 2020; 22:712-733. [PMID: 33167616 PMCID: PMC8284915 DOI: 10.1021/acscombsci.0c00179] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The power of ribosomes has increasingly been harnessed for the synthesis and selection of molecular libraries. Technologies, such as phage display, yeast display, and mRNA display, effectively couple genotype to phenotype for the molecular evolution of high affinity epitopes for many therapeutic targets. Genetic code expansion is central to the success of these technologies, allowing researchers to surpass the intrinsic capabilities of the ribosome and access new, genetically encoded materials for these selections. Here, we review techniques for the chemical expansion of genetically encoded libraries, their abilities and limits, and opportunities for further development. Importantly, we also discuss methods and metrics used to assess the efficiency of modification and library diversity with these new techniques.
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Affiliation(s)
- Sabrina E Iskandar
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Victoria A Haberman
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Albert A Bowers
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, United States
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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11
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Cui Z, Johnston WA, Alexandrov K. Cell-Free Approach for Non-canonical Amino Acids Incorporation Into Polypeptides. Front Bioeng Biotechnol 2020; 8:1031. [PMID: 33117774 PMCID: PMC7550873 DOI: 10.3389/fbioe.2020.01031] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Synthetic biology holds promise to revolutionize the life sciences and biomedicine via expansion of macromolecular diversity outside the natural chemical space. Use of non-canonical amino acids (ncAAs) via codon reassignment has found diverse applications in protein structure and interaction analysis, introduction of post-translational modifications, production of constrained peptides, antibody-drug conjugates, and novel enzymes. However, simultaneously encoding multiple ncAAs in vivo requires complex engineering and is sometimes restricted by the cell's poor uptake of ncAAs. In contrast the open nature of cell-free protein synthesis systems offers much greater freedom for manipulation and repurposing of the biosynthetic machinery by controlling the level and identity of translational components and reagents, and allows simultaneous incorporation of multiple ncAAs with non-canonical side chains and even backbones (N-methyl, D-, β-amino acids, α-hydroxy acids etc.). This review focuses on the two most used Escherichia coli-based cell-free protein synthesis systems; cell extract- and PURE-based systems. The former is a biological mixture with >500 proteins, while the latter consists of 38 individually purified biomolecules. We delineate compositions of these two systems and discuss their respective advantages and applications. Also, we dissect the translational components required for ncAA incorporation and compile lists of ncAAs that can be incorporated into polypeptides via different acylation approaches. We highlight the recent progress in using unnatural nucleobase pairs to increase the repertoire of orthogonal codons, as well as using tRNA-specific ribozymes for in situ acylation. We summarize advances in engineering of translational machinery such as tRNAs, aminoacyl-tRNA synthetases, elongation factors, and ribosomes to achieve efficient incorporation of structurally challenging ncAAs. We note that, many engineered components of biosynthetic machinery are developed for the use in vivo but are equally applicable to the in vitro systems. These are included in the review to provide a comprehensive overview for ncAA incorporation and offer new insights for the future development in cell-free systems. Finally, we highlight the exciting progress in the genomic engineering, resulting in E. coli strains free of amber and some redundant sense codons. These strains can be used for preparation of cell extracts offering multiple reassignment options.
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Affiliation(s)
- Zhenling Cui
- Synthetic Biology Laboratory, School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
| | - Wayne A Johnston
- Synthetic Biology Laboratory, School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kirill Alexandrov
- Synthetic Biology Laboratory, School of Biology and Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
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12
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Ribosomal synthesis and de novo discovery of bioactive foldamer peptides containing cyclic β-amino acids. Nat Chem 2020; 12:1081-1088. [PMID: 32839601 DOI: 10.1038/s41557-020-0525-1] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 07/15/2020] [Indexed: 02/05/2023]
Abstract
Peptides that contain β-amino acids display stable secondary structures, such as helices and sheets, and are often referred to as foldamers. Cyclic β2,3-amino acids (cβAAs), such as 2-aminocyclohexanecarboxylic acid (2-ACHC), are strong helix/turn inducers due to their restricted conformations. Here we report the ribosomal synthesis of foldamer peptides that contain multiple, up to ten, consecutive cβAAs via genetic code reprogramming. We also report the de novo discovery of macrocyclic cβAA-containing peptides capable of binding to a protein target. As a demonstration, potent binders with low-to-subnanomolar KD values were identified for human factor XIIa (hFXIIa) and interferon-gamma receptor 1, from a library of their 1012 members. One of the anti-hFXIIa macrocyclic peptides that exhibited a high inhibitory activity and serum stability was co-crystallized with hFXIIa. The X-ray structure revealed that it adopts an antiparallel β-sheet structure induced by a (1S,2S)-2-ACHC residue via the formation of two γ-turns. This work demonstrates the potential of this platform to explore the previously inaccessible sequence space of cβAA-containing peptides.
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13
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Ward FR, Watson ZL, Ad O, Schepartz A, Cate JHD. Defects in the Assembly of Ribosomes Selected for β-Amino Acid Incorporation. Biochemistry 2019; 58:4494-4504. [PMID: 31607123 PMCID: PMC8435211 DOI: 10.1021/acs.biochem.9b00746] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ribosome engineering has emerged as a promising field in synthetic biology, particularly concerning the production of new sequence-defined polymers. Mutant ribosomes have been developed that improve the incorporation of several nonstandard monomers including d-amino acids, dipeptides, and β-amino acids into polypeptide chains. However, there remains little mechanistic understanding of how these ribosomes catalyze incorporation of these new substrates. Here, we probed the properties of a mutant ribosome-P7A7-evolved for better in vivo β-amino acid incorporation through in vitro biochemistry and cryo-electron microscopy. Although P7A7 is a functional ribosome in vivo, it is inactive in vitro, and assembles poorly into 70S ribosome complexes. Structural characterization revealed large regions of disorder in the peptidyltransferase center and nearby features, suggesting a defect in assembly. Comparison of RNA helix and ribosomal protein occupancy with other assembly intermediates revealed that P7A7 is stalled at a late stage in ribosome assembly, explaining its weak activity. These results highlight the importance of ensuring efficient ribosome assembly during ribosome engineering toward new catalytic abilities.
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Affiliation(s)
- Fred R. Ward
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
| | - Zoe L. Watson
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
| | - Omer Ad
- Department of Chemistry, Yale University, New Haven, CT
| | - Alanna Schepartz
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, Yale University, New Haven, CT
| | - Jamie H. D. Cate
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA
- Department of Chemistry, University of California-Berkeley, Berkeley, CA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA
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14
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Hirose H, Tsiamantas C, Katoh T, Suga H. In vitro expression of genetically encoded non-standard peptides consisting of exotic amino acid building blocks. Curr Opin Biotechnol 2019; 58:28-36. [DOI: 10.1016/j.copbio.2018.10.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 10/26/2018] [Indexed: 01/04/2023]
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15
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Iqbal ES, Richardson SL, Abrigo NA, Dods KK, Osorio Franco HE, Gerrish HS, Kotapati HK, Morgan IM, Masterson DS, Hartman MCT. A new strategy for the in vitro selection of stapled peptide inhibitors by mRNA display. Chem Commun (Camb) 2019; 55:8959-8962. [PMID: 31290487 DOI: 10.1039/c8cc10192b] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hydrocarbon stapled peptides are promising therapeutics for inhibition of intracellular protein-protein interactions. Here we develop a new high-throughput strategy for hydrocarbon stapled peptide discovery based on mRNA display of peptides containing α-methyl cysteine and cyclized with m-dibromoxylene. We focus on development of a peptide binder to the HPV16 E2 protein.
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Affiliation(s)
- Emil S Iqbal
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - Stacie L Richardson
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - Nicolas A Abrigo
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - Kara K Dods
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - H Estheban Osorio Franco
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - Heather S Gerrish
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
| | - Hari Kiran Kotapati
- School of Mathematics & Natural Sciences, Chemistry & Biochemistry, 118 College Drive #5043, Hattiesburg, MS 39406, USA
| | - Iain M Morgan
- Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA and Philips Institute for Oral Health Research, Department of Oral and Craniofacial Molecular Biology, School of Dentistry, Virginia Commonwealth University, Box 980566, Richmond, VA 23298, USA
| | - Douglas S Masterson
- School of Mathematics & Natural Sciences, Chemistry & Biochemistry, 118 College Drive #5043, Hattiesburg, MS 39406, USA
| | - Matthew C T Hartman
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P. O. Box 842006, Richmond, VA 23284, USA. and Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, VA 23298, USA
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16
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Crnković A, Vargas-Rodriguez O, Söll D. Plasticity and Constraints of tRNA Aminoacylation Define Directed Evolution of Aminoacyl-tRNA Synthetases. Int J Mol Sci 2019; 20:ijms20092294. [PMID: 31075874 PMCID: PMC6540133 DOI: 10.3390/ijms20092294] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 04/29/2019] [Accepted: 05/07/2019] [Indexed: 02/07/2023] Open
Abstract
Genetic incorporation of noncanonical amino acids (ncAAs) has become a powerful tool to enhance existing functions or introduce new ones into proteins through expanded chemistry. This technology relies on the process of nonsense suppression, which is made possible by directing aminoacyl-tRNA synthetases (aaRSs) to attach an ncAA onto a cognate suppressor tRNA. However, different mechanisms govern aaRS specificity toward its natural amino acid (AA) substrate and hinder the engineering of aaRSs for applications beyond the incorporation of a single l-α-AA. Directed evolution of aaRSs therefore faces two interlinked challenges: the removal of the affinity for cognate AA and improvement of ncAA acylation. Here we review aspects of AA recognition that directly influence the feasibility and success of aaRS engineering toward d- and β-AAs incorporation into proteins in vivo. Emerging directed evolution methods are described and evaluated on the basis of aaRS active site plasticity and its inherent constraints.
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Affiliation(s)
- Ana Crnković
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
| | - Oscar Vargas-Rodriguez
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
| | - Dieter Söll
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
- Department of Chemistry, Yale University, New Haven, CT 06520, USA.
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17
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Huang Y, Wiedmann MM, Suga H. RNA Display Methods for the Discovery of Bioactive Macrocycles. Chem Rev 2018; 119:10360-10391. [PMID: 30395448 DOI: 10.1021/acs.chemrev.8b00430] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The past two decades have witnessed the emergence of macrocycles, including macrocyclic peptides, as a promising yet underexploited class of de novo drug candidates. Both rational/computational design and in vitro display systems have contributed tremendously to the development of cyclic peptide binders of either traditional targets such as cell-surface receptors and enzymes or challenging targets such as protein-protein interaction surfaces. mRNA display, a key platform technology for the discovery of cyclic peptide ligands, has become one of the leading strategies that can generate natural-product-like macrocyclic peptide binders with antibody-like affinities. On the basis of the original cell-free transcription/translation system, mRNA display is highly evolvable to realize its full potential by applying genetic reprogramming and chemical/enzymatic modifications. In addition, mRNA display also allows the follow-up hit-to-lead development using high-throughput focused affinity maturation. Finally, mRNA-displayed peptides can be readily engineered to create chemical conjugates based on known small molecules or biologics. This review covers the birth and growth of mRNA display and discusses the above features of mRNA display with success stories and future perspectives and is up to date as of August 2018.
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Affiliation(s)
- Yichao Huang
- Department of Chemistry, Graduate School of Science , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-0033 , Japan
| | - Mareike Margarete Wiedmann
- Department of Chemistry, Graduate School of Science , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-0033 , Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-0033 , Japan
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18
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Abstract
Due to their unique characteristics, which are not shared by canonical α-peptides, peptides that contain stretches of consecutive β-amino acids are attractive scaffolds for novel peptide drugs and nanomaterials. Although ribosomal incorporation of single or nonconsecutive β-amino acids into peptides has previously been reported, the incorporation of consecutive β-amino acids has not yet been accomplished. This is primarily due to their incompatibility with the ribosomal translation system. Here, we took advantage of engineered β-aminoacyl-tRNAs bearing optimized T-stem and D-arm motifs for enhancing binding affinity to EF-Tu and EF-P, respectively. Combined with a reconstituted E. coli translation system and optimized translation factor concentrations, up to seven consecutive β-amino acids could be incorporated into a model peptide. Furthermore, the synthesis of macrocyclic β-peptides closed by a thioether bond between two d-α-amino acids is also demonstrated. This represents the first example of the ribosomal synthesis of peptides containing stretches of consecutive β-amino acids.
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Affiliation(s)
- Takayuki Katoh
- Department of Chemistry, Graduate School of Science , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku , Tokyo 113-0033 , Japan.,JST, PRESTO, 7-3-1 Hongo , Bunkyo-ku , Tokyo 113-0033 , Japan
| | - Hiroaki Suga
- Department of Chemistry, Graduate School of Science , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku , Tokyo 113-0033 , Japan
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19
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Richardson SL, Dods KK, Abrigo NA, Iqbal ES, Hartman MC. In vitro genetic code reprogramming and expansion to study protein function and discover macrocyclic peptide ligands. Curr Opin Chem Biol 2018; 46:172-179. [PMID: 30077877 DOI: 10.1016/j.cbpa.2018.07.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 05/02/2018] [Accepted: 07/13/2018] [Indexed: 01/26/2023]
Abstract
The ability to introduce non-canonical amino acids into peptides and proteins is facilitated by working within in vitro translation systems. Non-canonical amino acids can be introduced into these systems using sense codon reprogramming, stop codon suppression, and by breaking codon degeneracy. Here, we review how these techniques have been used to create proteins with novel properties and how they facilitate sophisticated studies of protein function. We also discuss how researchers are using in vitro translation experiments with non-canonical amino acids to explore the tolerance of the translation apparatus to artificial building blocks. Finally, we give several examples of how non-canonical amino acids can be combined with mRNA-displayed peptide libraries for the creation of protease-stable, macrocyclic peptide libraries for ligand discovery.
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Affiliation(s)
- Stacie L Richardson
- Department of Chemistry, Virginia Commonwealth University (VCU), 1001 West Main Street, P.O. Box 842006, Richmond, USA; Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, USA
| | - Kara K Dods
- Department of Chemistry, Virginia Commonwealth University (VCU), 1001 West Main Street, P.O. Box 842006, Richmond, USA; Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, USA
| | - Nicolas A Abrigo
- Department of Chemistry, Virginia Commonwealth University (VCU), 1001 West Main Street, P.O. Box 842006, Richmond, USA; Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, USA
| | - Emil S Iqbal
- Department of Chemistry, Virginia Commonwealth University (VCU), 1001 West Main Street, P.O. Box 842006, Richmond, USA; Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, USA
| | - Matthew Ct Hartman
- Department of Chemistry, Virginia Commonwealth University (VCU), 1001 West Main Street, P.O. Box 842006, Richmond, USA; Massey Cancer Center, Virginia Commonwealth University, 401 College Street, Richmond, USA.
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