Laboratoire de Microbiologie et Génétique Moléculaires, Centre National de la Recherche Scientifique and Université Paul Sabatier, 31000 Toulouse, France.
Cell Stress Chaperones. 2013 Mar;18(2):129-35. doi: 10.1007/s12192-012-0396-5. Epub 2012 Dec 22.
Bacterial type II toxin-antitoxins (TAs) are two-component systems that modulate growth in response to specific stress conditions, thus promoting adaptation and persistence. The major human pathogen Mycobacterium tuberculosis potentially encodes 75 TAs and it has been proposed that persistence induced by active toxins might be relevant for its pathogenesis. In this work, we focus on the newly discovered toxin-antitoxin-chaperone (TAC) system of M. tuberculosis, an atypical stress-responsive TA system tightly controlled by a molecular chaperone that shows similarity to the canonical SecB chaperone involved in Sec-dependent protein export in Gram-negative bacteria. We performed a large-scale genome screening to reconstruct the evolutionary history of TAC systems and found that TAC is not restricted to mycobacteria and seems to have disseminated in diverse taxonomic groups by horizontal gene transfer. Our results suggest that TAC chaperones are evolutionary related to the solitary chaperone SecB and have diverged to become specialized toward their cognate antitoxins.
细菌 II 型毒素-抗毒素（TA）是一种由两个部分组成的系统，可根据特定的应激条件来调节生长，从而促进适应和持久性。主要的人类病原体结核分枝杆菌可能编码 75 个 TA，有人提出，活性毒素诱导的持久性可能与其发病机制有关。在这项工作中，我们专注于新发现的结核分枝杆菌毒素-抗毒素-伴侣（TAC）系统，这是一种典型的应激反应 TA 系统，受到分子伴侣的严格控制，该分子伴侣与参与革兰氏阴性细菌中 Sec 依赖性蛋白输出的典型 SecB 伴侣相似。我们进行了大规模的基因组筛选，以重建 TAC 系统的进化历史，发现 TAC 不仅限于分枝杆菌，而且似乎通过水平基因转移在不同的分类群中传播。我们的研究结果表明，TAC 伴侣与单独的伴侣 SecB 具有进化上的关系，并已分化成为其同源抗毒素的专门伴侣。
