Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, 60208, USA.
Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
Nat Commun. 2022 Oct 24;13(1):6322. doi: 10.1038/s41467-022-33701-2.
The ribosome is a macromolecular machine that catalyzes the sequence-defined polymerization of L-α-amino acids into polypeptides. The catalysis of peptide bond formation between amino acid substrates is based on entropy trapping, wherein the adjacency of transfer RNA (tRNA)-coupled acyl bonds in the P-site and the α-amino groups in the A-site aligns the substrates for coupling. The plasticity of this catalytic mechanism has been observed in both remnants of the evolution of the genetic code and modern efforts to reprogram the genetic code (e.g., ribosomal incorporation of non-canonical amino acids, ribosomal ester formation). However, the limits of ribosome-mediated polymerization are underexplored. Here, rather than peptide bonds, we demonstrate ribosome-mediated polymerization of pyridazinone bonds via a cyclocondensation reaction between activated γ-keto and α-hydrazino ester monomers. In addition, we demonstrate the ribosome-catalyzed synthesis of peptide-hybrid oligomers composed of multiple sequence-defined alternating pyridazinone linkages. Our results highlight the plasticity of the ribosome's ancient bond-formation mechanism, expand the range of non-canonical polymeric backbones that can be synthesized by the ribosome, and open the door to new applications in synthetic biology.
核糖体是一种大分子机器，能够催化 L-α-氨基酸序列特异性聚合成长肽。肽键形成的催化作用基于熵捕获，其中连接在 P 位的转移 RNA（tRNA）-结合的酰基键和在 A 位的α-氨基基团的邻近性使底物发生偶联。这种催化机制的可塑性在遗传密码进化的残留物和现代重新编程遗传密码的努力中都得到了观察（例如，核糖体掺入非规范氨基酸、核糖体酯形成）。然而，核糖体介导的聚合的限制尚未得到充分探索。在这里，我们通过激活的γ-酮和α-酰氨基酯单体之间的环缩合反应，证明了核糖体介导的嘧啶二酮键的聚合。此外，我们还证明了核糖体催化合成由多个序列定义的交替嘧啶二酮键组成的肽混合寡聚物。我们的结果突出了核糖体古老的键形成机制的可塑性，扩展了核糖体可以合成的非规范聚合骨架的范围，并为合成生物学中的新应用开辟了道路。
