Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery

3,4-Dihydroxy-L-phenylalanine (DOPA) is a promising noncanonical amino acid (ncAA) that introduces novel catechol chemical features into proteins, expanding their functional potential. However, the most common approach to incorporating ncAAs into proteins relies on stop codon suppression, which is o...

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Main Authors: Youhui Yang, Yingchen Wang, Zhaoguan Wang, Hao Qi
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Biomolecules
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Online Access:https://www.mdpi.com/2218-273X/15/3/382
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author Youhui Yang
Yingchen Wang
Zhaoguan Wang
Hao Qi
author_facet Youhui Yang
Yingchen Wang
Zhaoguan Wang
Hao Qi
author_sort Youhui Yang
collection DOAJ
description 3,4-Dihydroxy-L-phenylalanine (DOPA) is a promising noncanonical amino acid (ncAA) that introduces novel catechol chemical features into proteins, expanding their functional potential. However, the most common approach to incorporating ncAAs into proteins relies on stop codon suppression, which is often limited by the competition of endogenous translational termination machinery. Here, we employed a special in vitro protein expression system that facilitates the efficiency of DOPA incorporation into proteins by removing essential Class I peptide release factors through targeted degradation. In the absence of both RF1 and RF2, we successfully demonstrated DOPA incorporation at all three stop codons (TAG, TAA, and TGA). By optimizing the concentration of engineered DOPA-specific aminoacyl-tRNA synthetase (DOPARS), DOPA, and DNA template, we achieved a synthesis yield of 2.24 µg of sfGFP with 100% DOPA incorporation in a 20 μL reaction system. DOPARS exhibited a dissociation constant (<i>Kd</i>) of 11.7 μM for DOPA but showed no detectable binding to its native counterpart, tyrosine. Additionally, DOPA was successfully incorporated into a reverse transcriptase, which interfered with its activity. This system demonstrates a fast and efficient approach for precise DOPA incorporation into proteins, paving the way for advanced protein engineering applications.
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spelling doaj-art-d015d2ca6f2d41d0b2c88962d496acaa2025-08-20T02:11:22ZengMDPI AGBiomolecules2218-273X2025-03-0115338210.3390/biom15030382Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination MachineryYouhui Yang0Yingchen Wang1Zhaoguan Wang2Hao Qi3School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, ChinaSchool of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, ChinaSchool of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, ChinaSchool of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China3,4-Dihydroxy-L-phenylalanine (DOPA) is a promising noncanonical amino acid (ncAA) that introduces novel catechol chemical features into proteins, expanding their functional potential. However, the most common approach to incorporating ncAAs into proteins relies on stop codon suppression, which is often limited by the competition of endogenous translational termination machinery. Here, we employed a special in vitro protein expression system that facilitates the efficiency of DOPA incorporation into proteins by removing essential Class I peptide release factors through targeted degradation. In the absence of both RF1 and RF2, we successfully demonstrated DOPA incorporation at all three stop codons (TAG, TAA, and TGA). By optimizing the concentration of engineered DOPA-specific aminoacyl-tRNA synthetase (DOPARS), DOPA, and DNA template, we achieved a synthesis yield of 2.24 µg of sfGFP with 100% DOPA incorporation in a 20 μL reaction system. DOPARS exhibited a dissociation constant (<i>Kd</i>) of 11.7 μM for DOPA but showed no detectable binding to its native counterpart, tyrosine. Additionally, DOPA was successfully incorporated into a reverse transcriptase, which interfered with its activity. This system demonstrates a fast and efficient approach for precise DOPA incorporation into proteins, paving the way for advanced protein engineering applications.https://www.mdpi.com/2218-273X/15/3/382noncanonical amino acids3,4-dihydroxy-L-phenylalaninesfGFPaminoacyl-tRNA synthetase
spellingShingle Youhui Yang
Yingchen Wang
Zhaoguan Wang
Hao Qi
Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
Biomolecules
noncanonical amino acids
3,4-dihydroxy-L-phenylalanine
sfGFP
aminoacyl-tRNA synthetase
title Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
title_full Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
title_fullStr Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
title_full_unstemmed Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
title_short Efficient Incorporation of DOPA into Proteins Free from Competition with Endogenous Translation Termination Machinery
title_sort efficient incorporation of dopa into proteins free from competition with endogenous translation termination machinery
topic noncanonical amino acids
3,4-dihydroxy-L-phenylalanine
sfGFP
aminoacyl-tRNA synthetase
url https://www.mdpi.com/2218-273X/15/3/382
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AT yingchenwang efficientincorporationofdopaintoproteinsfreefromcompetitionwithendogenoustranslationterminationmachinery
AT zhaoguanwang efficientincorporationofdopaintoproteinsfreefromcompetitionwithendogenoustranslationterminationmachinery
AT haoqi efficientincorporationofdopaintoproteinsfreefromcompetitionwithendogenoustranslationterminationmachinery