Ries Fabian, Gorlt Jasmin, Kaiser Sabrina, Scherer Vanessa, Seydel Charlotte, Nguyen Sandra, Klingl Andreas, Legen Julia, Schmitz-Linneweber Christian, Plaggenborg Hinrik, Ng Jediael Z Y, Wiens Dennis, Hochberg Georg K A, Räschle Markus, Möhlmann Torsten, Scheuring David, Willmund Felix
Molecular Genetics of Eukaryotes, University of Kaiserslautern, Kaiserslautern, Germany.
Institute of Systems Biotechnology, Saarland University, Saarbrücken, Germany.
Nat Commun. 2025 Jan 13;16(1):629. doi: 10.1038/s41467-025-55813-1.
Molecular chaperones are essential throughout a protein's life and act already during protein synthesis. Bacteria and chloroplasts of plant cells share the ribosome-associated chaperone trigger factor (Tig1 in plastids), facilitating maturation of emerging nascent polypeptides. While typical trigger factor chaperones employ three domains for their task, the here described truncated form, Tig2, contains just the ribosome binding domain. Tig2 is widely present in green plants and appears to have acquired an entirely different task than co-translational nascent polypeptide folding. Tig2 deletion results in remarkable leaf developmental defects of cold-exposed Arabidopsis thaliana plants and specific defects in plastidic ribosomes. Our data indicate that Tig2 functions during ribosome biogenesis by promoting the maturation of the large subunit. We hypothesize that Tig2 binding to the ribosomal tunnel-exit surface aids protecting this sensitive surface during assembly. Tig2 illustrates a fascinating concept of how a chaperone domain evolved individually, serving a completely different molecular task.
分子伴侣在蛋白质的整个生命周期中都至关重要，甚至在蛋白质合成过程中就已发挥作用。植物细胞的细菌和叶绿体共享与核糖体相关的伴侣触发因子（质体中的Tig1），促进新生多肽的成熟。典型的触发因子伴侣利用三个结构域来完成其任务，而此处描述的截短形式Tig2仅包含核糖体结合结构域。Tig2广泛存在于绿色植物中，似乎已获得了与共翻译新生多肽折叠完全不同的任务。Tig2缺失会导致冷处理的拟南芥植株出现明显的叶片发育缺陷以及质体核糖体的特定缺陷。我们的数据表明，Tig2通过促进大亚基的成熟在核糖体生物发生过程中发挥作用。我们推测，Tig2与核糖体隧道出口表面的结合有助于在组装过程中保护这个敏感表面。Tig2阐明了一个引人入胜的概念，即伴侣结构域如何独立进化，承担完全不同的分子任务。
