Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
Adv Protein Chem Struct Biol. 2012;86:151-91. doi: 10.1016/B978-0-12-386497-0.00005-0.
The bacterial tmRNA quality control system monitors protein synthesis and recycles stalled translation complexes in a process termed "ribosome rescue." During rescue, tmRNA acts first as a transfer RNA to bind stalled ribosomes, then as a messenger RNA to add the ssrA peptide tag to the C-terminus of the nascent polypeptide chain. The ssrA peptide targets tagged peptides for proteolysis, ensuring rapid degradation of potentially deleterious truncated polypeptides. Ribosome rescue also facilitates turnover of the damaged messages responsible for translational arrest. Thus, tmRNA increases the fidelity of gene expression by promoting the synthesis of full-length proteins. In addition to serving as a global quality control system, tmRNA also plays important roles in bacterial development, pathogenesis, and environmental stress responses. This review focuses on the mechanism of tmRNA-mediated ribosome rescue and the role of tmRNA in bacterial physiology.
细菌 tmRNA 质量控制系统监测蛋白质合成，并在称为“核糖体救援”的过程中回收停滞的翻译复合物。在救援过程中，tmRNA 首先作为转移 RNA 结合停滞的核糖体，然后作为信使 RNA 将 ssrA 肽标签添加到新生多肽链的 C 末端。ssrA 肽将标记的肽靶向蛋白酶解，确保快速降解潜在有害的截短多肽。核糖体救援还促进了负责翻译阻滞的受损信使的周转。因此，tmRNA 通过促进全长蛋白的合成来提高基因表达的保真度。除了作为一个全局质量控制系统外，tmRNA 在细菌发育、发病机制和环境应激反应中也发挥着重要作用。本综述重点介绍 tmRNA 介导的核糖体救援机制以及 tmRNA 在细菌生理学中的作用。
