Ogawa Tetsuhiro
a Department of Biotechnology , The University of Tokyo , Tokyo , Japan.
Biosci Biotechnol Biochem. 2016 Jun;80(6):1037-45. doi: 10.1080/09168451.2016.1148579. Epub 2016 Mar 11.
Most bacteria produce antibacterial proteins known as bacteriocins, which aid bacterial defence systems to provide a physiological advantage. To date, many kinds of bacteriocins have been characterized. Colicin has long been known as a plasmidborne bacteriocin that kills other Escherichia coli cells lacking the same plasmid. To defeat other cells, colicins exert specific activities such as ion-channel, DNase, and RNase activity. Colicin E5 and colicin D impair protein synthesis in sensitive E. coli cells; however, their physiological targets have not long been identified. This review describes our finding that colicins E5 and D are novel RNases targeting specific E. coli tRNAs and elucidates their enzymatic properties based on biochemical analyses and X-ray crystal structures. Moreover, tRNA cleavage mediates bacteriostasis, which depends on trans-translation. Based on these results and others, cell growth regulation depending on tRNA cleavage is also discussed.
大多数细菌会产生被称为细菌素的抗菌蛋白，这些蛋白有助于细菌防御系统获得生理优势。迄今为止，已鉴定出多种细菌素。大肠杆菌素长期以来被认为是一种由质粒携带的细菌素，它能杀死其他缺乏相同质粒的大肠杆菌细胞。为了击败其他细胞，大肠杆菌素发挥特定活性，如离子通道、DNA酶和RNA酶活性。大肠杆菌素E5和大肠杆菌素D会损害敏感大肠杆菌细胞中的蛋白质合成；然而，它们的生理靶点长期以来一直未被确定。本综述描述了我们的发现，即大肠杆菌素E5和D是靶向特定大肠杆菌tRNA的新型RNA酶，并基于生化分析和X射线晶体结构阐明了它们的酶学特性。此外，tRNA切割介导抑菌作用，这依赖于反式翻译。基于这些结果及其他研究，还讨论了依赖于tRNA切割的细胞生长调控。
