Jurėnas Dukas, Van Melderen Laurence
Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, Aix-Marseille Université, Marseille, France.
Cellular and Molecular Microbiology, Faculté des Sciences, Université libre de Bruxelles, Gosselies, Belgium.
Front Genet. 2020 Apr 17;11:262. doi: 10.3389/fgene.2020.00262. eCollection 2020.
Type II Toxin-antitoxin (TA) modules are bacterial operons that encode a toxic protein and its antidote, which form a self-regulating genetic system. Antitoxins put a halter on toxins in many ways that distinguish different types of TA modules. In type II TA modules, toxin and antitoxin are proteins that form a complex which physically sequesters the toxin, thereby preventing its toxic activity. Type II toxins inhibit various cellular processes, however, the translation process appears to be their favorite target and nearly every step of this complex process is inhibited by type II toxins. The structural features, enzymatic activities and target specificities of the different toxin families are discussed. Finally, this review emphasizes that the structural folds presented by these toxins are not restricted to type II TA toxins or to one particular cellular target, and discusses why so many of them evolved to target translation as well as the recent developments regarding the role(s) of these systems in bacterial physiology and evolution.
II型毒素-抗毒素（TA）模块是细菌操纵子，编码一种毒性蛋白及其解毒剂，它们构成一个自我调节的遗传系统。抗毒素通过多种方式抑制毒素，这些方式区分了不同类型的TA模块。在II型TA模块中，毒素和抗毒素是形成复合物的蛋白质，该复合物通过物理方式隔离毒素，从而阻止其毒性活性。II型毒素抑制各种细胞过程，然而，翻译过程似乎是它们最喜欢的靶标，并且这个复杂过程的几乎每一步都受到II型毒素的抑制。本文讨论了不同毒素家族的结构特征、酶活性和靶标特异性。最后，本综述强调这些毒素呈现的结构折叠并不局限于II型TA毒素或某一特定细胞靶标，并讨论了为何如此多的毒素进化为靶向翻译过程，以及这些系统在细菌生理学和进化中的作用的最新进展。
