Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2025.01.22.631627

A robust platform streamlining aromatic noncanonical amino acid biosynthesis and genetic code expansion in E. coli

Zhang, J.·Yu, K.·Xu, Y.·Zhao, W.·Li, Y.·Wang, Y.·Seebeck, F. P.·Chen, X.·Liao, C.
View original source ↗Export metadata ↓

Abstract

Genetic code expansion has significantly enhanced the diversity and functionality of proteins in the biological world, leading to a wide range of applications in catalysis, biology, and medicine. Despite the extraordinary advances in genetic code expansion over the past years, the availability and cost of noncanonical amino acids (ncAAs) remain one of the major obstacles, particularly for large-scale industrial production. In situ biosynthesis of ncAAs from commercially available precursors offers a promising solution to this challenge, yet only a few biosynthetic pathways for specific amino acids have been reported to date. To address this gap, we present a robust platform that couples the biosynthesis of aromatic amino acids with genetic code expansion in E. coli, enabling the production of proteins and peptides containing incorporated ncAAs. Forty amino acids with diverse functional groups were synthesized from aryl aldehydes by a biosynthetic pathway comprising two heterologously expressed enzymes and one endogenous enzyme. Nineteen of these amino acids were successfully incorporated into superfolder GFP (sfGFP) using three classic orthogonal translation systems. The platforms versatility was further demonstrated by the production of macrocyclic peptides and antibodies containing functional ncAAs, such as para-azidophenylalanine and para-boronophenylalanine. We envision that the simplicity, efficiency, compatibility, and broad applicability of this biosynthetic pathway and the platform will greatly facilitate the production of peptides, enzymes, and antibodies containing ncAAs, thereby accelerating their use in various applications. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/631627v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@8a6d2eorg.highwire.dtl.DTLVardef@5f8b9org.highwire.dtl.DTLVardef@c514aorg.highwire.dtl.DTLVardef@acd66d_HPS_FORMAT_FIGEXP M_FIG C_FIG

Source connections

Explore related subjects

synthetic biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Zhang, J., Yu, K., Xu, Y., Zhao, W., Li, Y., Wang, Y., Seebeck, F. P., Chen, X., Liao, C.. 2025-01-22. A robust platform streamlining aromatic noncanonical amino acid biosynthesis and genetic code expansion in E. coli. https://doi.org/10.1101/2025.01.22.631627

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Living electronic transistors with tunable conductivity

Electroactive bacteria, like Shewanella oneidensis, can couple the oxidation of organic electron donors to the reduction of external conductive surfaces, such as minerals and electrodes, by utilizing multiheme cytochromes to carry charge from within the cell to external surfaces. Additionally, multiheme cytochromes facilitate gateable, long-distance (micrometer-scale) redox conduction along the outer membrane and across multiple cells bridging electrodes. While electroactive microbes are being used to develop bioelectrochemical devices, there have been limited efforts to use synthetic biology to exert additional control over microbes serving as device components. Thus, this work implements an optogenetic biofilm patterning gene circuit and a small molecule sensor in S. oneidensis to simultaneously control cell deposition and cytochrome expression. This allows for photolithographic patterning of biofilms possessing tunable electrical properties controlled with small molecules. This system demonstrates tunable electrochemical activity, redox conduction, intrinsic biofilm conductivity, and negative differential transconductance as a function of cytochrome expression. Additionally, temperature-dependent measurements of this tunable biofilm conduction reveal changes in activation energy as a function of cytochrome expression. Through this combination of synthetic biology and electrochemistry, simultaneous control over biofilm geometry and conductivity sheds light on fundamental microbial electron transport processes, and it enables the construction of living electronic devices.

synthetic biology↗
bioRxiv2026

Evolutionary stabilisation of stressful metabolism via integrated biocomputing and essential-gene metabolic locking circuits

Synthetic genetic circuits enable microbial differentiation from growth to production, yet metabolic burden, imbalance and toxicity frequently drive strain degeneration. Yeast strains engineered to produce different terpene products exhibited divergent genetic responses to metabolic stresses, but commonly underwent progressive loss of induction of synthetic GAL regulatory circuits, either across the entire population or within subpopulations. Using di- and tri-input biocomputing circuits, the essential glutamine synthetase gene GLN1 was coupled to GAL induction, thereby enabling stabilisation and evolutionary adaptation of the synthetic genetic circuits and stressful heterologous terpene synthetic pathways. The integrated biocomputing and metabolic coupling circuit systems not only prevent strain degeneration but also enable interrogation of non-degenerative evolutionary shifts, providing a platform for metabolic engineering optimisation.

synthetic biology↗
bioRxiv2026

Unbiased and scalable reduction of diverse bacterial genomes

The genome is a complex, integrated system where the functions and regulatory interactions of its many components remain poorly understood. Genome minimization aims to reduce genomic complexity by removing non-essential elements to reveal the fundamental building blocks of cellular life. However, current minimization strategies are often slow and species-specific due to a reliance on prior information, and limited to producing single, isolated strains, which obscures the diverse ways a genome can adapt to large-scale DNA removal. Here we show the development and application of Stochastic Lineage-based Iterative Minimization (SLIM) a modular, high-throughput platform for unbiased genome reduction across phylogenetically diverse bacteria. We apply SLIM to generate a library of genome-reduced Escherichia coli lineages. We then interrogate the lineages, identifying both universal and lineage-specific transcriptional and translational reprogramming in response to deletions. We demonstrate that these expression dynamics drive environment-dependent fitness, allowing us to pinpoint a single gene deletion in one genome-reduced lineage as the driver of a measurable environmental growth defect. Beyond E. coli, we successfully deploy SLIM in phylogenetically distinct bacterial taxa to rapidly reduce the genomes of Shigella flexneri and Pseudomonas putida, distinct genus and order respectively from E. coli, without species-specific optimization. Our results establish a scalable, generalizable framework for navigating the vast landscape of minimized genomes, providing a powerful new tool for functional discovery and the rational design of synthetic genomic chassis.

synthetic biology↗