Otsuka Yuichi
Department of Microbiology, School of Medicine, Dokkyo Medical University, 880 Kitakobayashi, Mibu-machi, Shimotsuga-gun, Tochigi, 321-0293, Japan.
Curr Genet. 2016 May;62(2):379-82. doi: 10.1007/s00294-015-0557-z. Epub 2016 Jan 16.
Toxin-antitoxin (TA) systems are widely conserved in prokaryotic plasmids and chromosomes and are linked to many roles in cell physiology, including plasmid maintenance, stress response, persistence and protection from phage infection. A TA system is composed of a stable toxin and a labile antitoxin that inhibits a harmful effect of the cognate toxin. When gene expression from the TA loci is repressed under certain conditions such as nutrient starvation, the toxin is freed from the rapidly degrading antitoxin and obstructs an essential cellular process, such as DNA replication, translation and peptidoglycan synthesis, which subsequently causes growth arrest. TA systems are classified into five types according to the nature and the function of antitoxins, and the activity of toxins is tightly regulated in a variety of ways. This short-review highlights several novel regulatory mechanisms for Escherichia coli toxins that we recently discovered.
毒素-抗毒素（TA）系统广泛存在于原核生物的质粒和染色体中，并与细胞生理学中的许多作用相关联，包括质粒维持、应激反应、持留性以及抵御噬菌体感染。一个TA系统由一种稳定的毒素和一种不稳定的抗毒素组成，抗毒素可抑制同源毒素的有害作用。当TA位点的基因表达在某些条件下（如营养饥饿）受到抑制时，毒素会从快速降解的抗毒素中释放出来，并阻碍诸如DNA复制、翻译和肽聚糖合成等重要的细胞过程，进而导致生长停滞。根据抗毒素的性质和功能，TA系统可分为五种类型，并且毒素的活性通过多种方式受到严格调控。这篇简短综述重点介绍了我们最近发现的几种大肠杆菌毒素的新型调控机制。
