Ser/Leu-swapped cell-free translation system constructed with natural/in vitro transcribed-hybrid tRNA set.

Fujino, Tomoshige; Sonoda, Ryogo; Higashinagata, Taito; Mishiro-Sato, Emi; Kano, Keiko; Murakami, Hiroshi · Nat Commun · 2024

basic_science · Level V

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Abstract

The Ser/Leu-swapped genetic code can act as a genetic firewall, mitigating biohazard risks arising from horizontal gene transfer in genetically modified organisms. Our prior work demonstrated the orthogonality of this swapped code to the standard genetic code using a cell-free translation system comprised of 21 in vitro transcribed tRNAs. In this study, to advance this system for protein engineering, we introduce a natural/in vitro transcribed-hybrid tRNA set. This set combines natural tRNAs from Escherichia coli (excluding Ser, Leu, and Tyr) and in vitro transcribed tRNAs, encompassing anticodon-swapped tRNA<sup>Ser</sup><sub>GAG</sub> and tRNA<sup>Leu</sup><sub>GGA</sub>. This approach reduces the number of in vitro transcribed tRNAs required from 21 to only 4. In this optimized system, the production of a model protein, superfolder green fluorescent protein, increases to 3.5-fold. With this hybrid tRNA set, the Ser/Leu-swapped cell-free translation system will stand as a potent tool for protein production with reduced biohazard concerns in future biological endeavors.

Medical subject headings