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The pyrrolysyl-tRNA synthetase (PylRS) is widely used to incorporate noncanonical amino acids (ncAAs) into proteins. However, the yields of most ncAA-containing protein remain low due to the limited activity of PylRS variants. Here, we apply machine learning to engineer the tRNA-binding domain of PylRS. The FFT-PLSR model is first applied to explore pairwise combinations of 12 single mutations, generating a variant Com1-IFRS with an 11-fold increase in stop codon suppression (SCS) efficiency. Deep learning models ESM-1v, Mutcompute, and ProRefiner are then used to identify additional mutation sites. Applying FFT-PLSR on these sites yields a variant Com2-IFRS showing a 30.8-fold increase in SCS efficiency, and up to 7.8-fold improvement in the catalytic efficiency (k/K). Transplanting these mutations into 7 PylRS-derived synthetases significantly improves the yields of proteins containing 6 types of ncAAs. This paper presents improved PylRS variants and a machine learning framework for optimizing the enzyme activity.
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http://dx.doi.org/10.1038/s41467-025-61952-2 | DOI Listing |
Nat Commun
July 2025
Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
The pyrrolysyl-tRNA synthetase (PylRS) is widely used to incorporate noncanonical amino acids (ncAAs) into proteins. However, the yields of most ncAA-containing protein remain low due to the limited activity of PylRS variants. Here, we apply machine learning to engineer the tRNA-binding domain of PylRS.
View Article and Find Full Text PDFProteins are typically composed of 20 amino acids encoded by 61 codons. However, some bacteria and archaea have evolved to incorporate additional amino acids by repurposing stop codons, a phenomenon that led to the development of genetic code expansion (GCE) in the early 21st century. This approach introduces orthogonal tRNA and aminoacyl-tRNA-synthetase (aaRS) pairs into target organisms, enabling the incorporation of noncanonical amino acids (ncAAs) with distinct side chains into proteins.
View Article and Find Full Text PDFACS Chem Biol
April 2025
Institute of Physical Chemistry, Department of Chemistry, University of Basel, 4058 Basel, Switzerland.
Epitope mapping is crucial for understanding immunological responses to protein therapeutics. Here, we combined genetic code expansion and bacterial surface display to incorporate S-allylcysteine (SAC) into human arginase-1 (hArg1) via pyrrolysyl-tRNA synthetase. Using an amber codon deep mutational scanning and sequencing workflow, we mapped SAC incorporation efficiency across the hArg1 sequence, providing insights into structural and sequence dependencies of noncanonical amino acid incorporation.
View Article and Find Full Text PDFRSC Chem Biol
March 2025
School of Life Sciences & Center of Novel Biomaterials, The Chinese University of Hong Kong Shatin Hong Kong SAR
Here, we present a novel strategy that integrates genetic-code expansion and proximity-induced crosslinking to achieve site-specific SUMOylation. This approach involves incorporating the unnatural amino acid 2-chloroacetyl-ε-lysine (ClAcK) into the target protein using MmFAcKRS1, a previously reported pyrrolysyl-tRNA synthetase mutant that we have repurposed for ClAcK incorporation. Once incorporated, ClAcK can be specifically targeted to react with a cysteine engineered at the C-terminus of SUMO variants leading to a chemically SUMOylated protein.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
April 2025
Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts, 02467.
Site-specific incorporation of noncanonical amino acids (ncAAs) into proteins in eukaryotes has predominantly relied on the pyrrolysyl-tRNA synthetase/tRNA pair. However, access to additional easily engineered pairs is crucial for expanding the structural diversity of the ncAA toolbox in eukaryotes. The Escherichia coli-derived leucyl-tRNA synthetase (EcLeuRS)/tRNA pair presents a particularly promising alternative.
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