美国耶鲁大学Farren J. Isaacs和Jesse Rinehart研究组合作取得一项新突破。他们利用单终止密码子实现基因组重编码生物（GRO）改造。相关论文于2025年2月5日发表在《自然》杂志上。

研究人员描述了Ochre的构建和特性，这是一种能将翻译功能完全压缩到单个密码子中的GRO。研究人员在?TAG大肠杆菌C321.?A4中用同义的TAA取代了1195个TGA终止密码子。随后，研究人员设计了释放因子2（RF2）和tRNA^Trp来减轻自体UGA识别，从而在翻译中分离出四个具有非退化功能的密码子。

因此，Ochre利用UAA作为唯一的终止密码子，UGG编码色氨酸，UAG和UGA则得以重新分配，用于将两种不同的非标准氨基酸多位并入单个蛋白质，准确率超过99%。Ochre将退化的终止密码子完全压缩成单个密码子，这是向64个非退化密码子迈出的重要一步，它能精确产生具有非天然编码化学成分的多功能合成蛋白质，并广泛应用于生物技术和生物治疗。

研究人员表示，遗传密码在所有生命体中都是保守的，但例外情况揭示了密码子分配和相关翻译因子的变化。受这种天然延展性的启发，合成生物学已实现对同义密码子的全基因组替换，以构建具有替代遗传密码的GRO。然而，目前还没有充分利用翻译因子的可塑性和密码子的可变性，将翻译功能压缩到单一密码子上，并评估非变性代码的可能性。

附：英文原文

Title: Engineering a genomically recoded organism with one stop codon

Author: Grome, Michael W., Nguyen, Michael T. A., Moonan, Daniel W., Mohler, Kyle, Gurara, Kebron, Wang, Shenqi, Hemez, Colin, Stenton, Benjamin J., Cao, Yunteng, Radford, Felix, Kornaj, Maya, Patel, Jaymin, Prome, Maisha, Rogulina, Svetlana, Sozanski, David, Tordoff, Jesse, Rinehart, Jesse, Isaacs, Farren J.

Issue&Volume: 2025-02-05

Abstract: The genetic code is conserved across all domains of life, yet exceptions have revealed variations in codon assignments and associated translation factors1,2,3. Inspired by this natural malleability, synthetic approaches have demonstrated whole-genome replacement of synonymous codons to construct genomically recoded organisms (GROs)4,5 with alternative genetic codes. However, no efforts have fully leveraged translation factor plasticity and codon degeneracy to compress translation function to a single codon and assess the possibility of a non-degenerate code. Here we describe construction and characterization of Ochre, a GRO that fully compresses a translational function into a single codon. We replaced 1,195 TGA stop codons with the synonymous TAA in TAG Escherichia coli C321.A4. We then engineered release factor 2 (RF2) and tRNATrp to mitigate native UGA recognition, translationally isolating four codons for non-degenerate functions. Ochre thus utilizes UAA as the sole stop codon, with UGG encoding tryptophan and UAG and UGA reassigned for multi-site incorporation of two distinct non-standard amino acids into single proteins with more than 99% accuracy. Ochre fully compresses degenerate stop codons into a single codon and represents an important step toward a 64-codon non-degenerate code that will enable precise production of multi-functional synthetic proteins with unnatural encoded chemistries and broad utility in biotechnology and biotherapeutics.

DOI: 10.1038/s41586-024-08501-x

Source: https://www.nature.com/articles/s41586-024-08501-x