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Huang RL, Jewel D, Kelemen RE, Pham Q, Yared TJ, Wang S, Singha Roy SJ, Huang Z, Levinson SD, Sundaresh B, Miranda SE, van Opijnen T, Chatterjee A. Directed Evolution of a Bacterial Leucyl tRNA in Mammalian Cells for Enhanced Noncanonical Amino Acid Mutagenesis. ACS Synth Biol 2024. [PMID: 38904157 DOI: 10.1021/acssynbio.4c00196] [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: 06/22/2024]
Abstract
The Escherichia coli leucyl-tRNA synthetase (EcLeuRS)/tRNAEcLeu pair has been engineered to genetically encode a structurally diverse group of enabling noncanonical amino acids (ncAAs) in eukaryotes, including those with bioconjugation handles, environment-sensitive fluorophores, photocaged amino acids, and native post-translational modifications. However, the scope of this toolbox in mammalian cells is limited by the poor activity of tRNAEcLeu. Here, we overcome this limitation by evolving tRNAEcLeu directly in mammalian cells by using a virus-assisted selection scheme. This directed evolution platform was optimized for higher throughput such that the entire acceptor stem of tRNAEcLeu could be simultaneously engineered, which resulted in the identification of several variants with remarkably improved efficiency for incorporating a wide range of ncAAs. The advantage of the evolved leucyl tRNAs was demonstrated by expressing ncAA mutants in mammalian cells that were challenging to express before using the wild-type tRNAEcLeu, by creating viral vectors that facilitated ncAA mutagenesis at a significantly lower dose and by creating more efficient mammalian cell lines stably expressing the ncAA-incorporation machinery.
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Affiliation(s)
- Rachel L Huang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Delilah Jewel
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Rachel E Kelemen
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Quan Pham
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Tarah J Yared
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Shu Wang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | | | - Zeyi Huang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Samantha D Levinson
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Bharathi Sundaresh
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | | | - Tim van Opijnen
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States
| | - Abhishek Chatterjee
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
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Jewel D, Kelemen RE, Huang RL, Zhu Z, Sundaresh B, Malley K, Pham Q, Loynd C, Huang Z, van Opijnen T, Chatterjee A. Enhanced Directed Evolution in Mammalian Cells Yields a Hyperefficient Pyrrolysyl tRNA for Noncanonical Amino Acid Mutagenesis. Angew Chem Int Ed Engl 2024; 63:e202316428. [PMID: 38279536 PMCID: PMC10922736 DOI: 10.1002/anie.202316428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Indexed: 01/28/2024]
Abstract
Heterologous tRNAs used for noncanonical amino acid (ncAA) mutagenesis in mammalian cells typically show poor activity. We recently introduced a virus-assisted directed evolution strategy (VADER) that can enrich improved tRNA mutants from naïve libraries in mammalian cells. However, VADER was limited to processing only a few thousand mutants; the inability to screen a larger sequence space precluded the identification of highly active variants with distal synergistic mutations. Here, we report VADER2.0, which can process significantly larger mutant libraries. It also employs a novel library design, which maintains base-pairing between distant residues in the stem regions, allowing us to pack a higher density of functional mutants within a fixed sequence space. VADER2.0 enabled simultaneous engineering of the entire acceptor stem of M. mazei pyrrolysyl tRNA (tRNAPyl ), leading to a remarkably improved variant, which facilitates more efficient incorporation of a wider range of ncAAs, and enables facile development of viral vectors and stable cell-lines for ncAA mutagenesis.
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Affiliation(s)
- Delilah Jewel
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Rachel E Kelemen
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Rachel L Huang
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Zeyu Zhu
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | | | - Kaitlin Malley
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Quan Pham
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Conor Loynd
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Zeyi Huang
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | - Tim van Opijnen
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Abhishek Chatterjee
- Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
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