Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät, AG Bakteriengenetik, Jena, Germany.
RNA Biol. 2012 Dec;9(12):1488-90. doi: 10.4161/rna.23045. Epub 2012 Dec 1.
Toxin-antitoxin (TA) loci encode two-component systems that consist of a stable "toxin" whose ectopic overexpression either kills cells or confers growth stasis, and an unstable "antitoxin". TA systems have been initially discovered on plasmids, where they confer stability of maintenance through post-segregational killing (PSK). Plasmid loss results in rapid decrease of antitoxin levels, which allows the stable toxin to kill the plasmid-free cell. Later, TA systems were also found on bacterial and archaeal chromosomes, sometimes in staggering numbers. (1), (2) They are classified into five types depending on the nature and action of the antitoxin. In type I systems, the antitoxin is a small antisense RNA that base-pairs with the toxin encoding mRNA. By contrast, in type II systems, the antitoxin is a protein that interacts post-translationally with the toxin protein. The antitoxin in type III systems is a pseudoknot containing RNA that directly binds the toxin protein. (3), (4) In the recently proposed type IV systems, the protein antitoxin interferes with binding of the toxin to its target rather than inhibiting the toxin directly by binding, (5) whereas the antitoxin protein in type V systems cleaves the toxin-encoding mRNA. (6).
毒素-抗毒素 (TA) 基因座编码由两个组件组成的系统，其中包括稳定的“毒素”，其异位过表达要么杀死细胞，要么导致生长停滞，以及不稳定的“抗毒素”。TA 系统最初在质粒上被发现，它们通过继代后杀伤（PSK）赋予维持稳定性。质粒丢失会导致抗毒素水平迅速下降，从而使稳定的毒素杀死无质粒细胞。后来，TA 系统也在细菌和古细菌染色体上被发现，有时数量惊人。（1），（2）它们根据抗毒素的性质和作用分为五类。在 I 型系统中，抗毒素是与毒素编码 mRNA 碱基配对的小反义 RNA。相比之下，在 II 型系统中，抗毒素是一种与毒素蛋白相互作用的蛋白质。III 型系统中的抗毒素是一种含有 RNA 的假结，可直接结合毒素蛋白。（3），（4）在最近提出的 IV 型系统中，蛋白抗毒素通过干扰毒素与其靶标的结合而不是直接通过结合来抑制毒素，（5）而 V 型系统中的抗毒素蛋白则切割毒素编码的 mRNA。（6）。
