Mycoplasmas are minute bacteria controlled by very small genomes ranging from 0.6 to 1.4 Mbp. They lack a cell wall and have been suggested to have progressed through reductive evolution from phylogenetically closely related Clostridia. They are known to colonize the respiratory tract or the urogenital tract among other organs and can cause chronic and subclinical diseases associated with long persistence of the causative agent. Toxin-antitoxin systems (TAS) are genetic elements that have been described for several respiratory and urogenital pathogens as well as for Clostridia, but never for pathogenic mycoplasmas. Here we describe for the first-time different types of TAS in a Mycoplasma pathogen, namely M. mycoides subsp. capri . We identified candidate TAS in silico via TASmania database. Two candidate TAS identified in silico and another candidate TAS suggested in a minimal cell based on transposon mutagenesis were systematically tested for their functionality in hosts with different phylogenetic distance using heterologous expression. Phylogenetic distance of the host used for heterologous expression influenced the outcome of the functional testing. We corroborated functionality of the three candidate TAS in Mycoplasma capricolum subsp. capricolum . Moreover, we confirmed transcription and translation of molecules of the TAS investigated during in vitro growth. We sequence analyzed 15 genomes of M. mycoides subsp. capri and revealed an unequal distribution of the TAS studied pointing towards dynamic gain and loss of TAS within the species.

中文翻译：

---

简约支原体具有不同的功能性毒素-抗毒素系统

支原体是微小的细菌，受0.6至1.4 Mbp的非常小的基因组控制。它们缺乏细胞壁，并且已被建议通过系统发育上密切相关的梭状芽胞杆菌的还原进化而发展。已知它们会在其他器官中定居于呼吸道或泌尿生殖道，并可能引起与病因长期持续有关的慢性和亚临床疾病。毒素-抗毒素系统（TAS）是已针对多种呼吸道和泌尿生殖道病原体以及梭状芽胞杆菌描述的遗传元素，但从未针对致病性支原体描述。在这里，我们首次描述了支原体病原体，即M. mycoides亚种中的TAS的不同类型。卡普里岛。我们通过TASmania数据库在计算机上确定了候选TAS。使用异源表达系统地测试了两个在计算机上鉴定的候选TAS和在基于转座子诱变的最小细胞中建议的另一个候选TAS在具有不同系统发生距离的宿主中的功能。用于异源表达的宿主的系统发生距离影响功能测试的结果。我们证实了支原体亚种中三个候选TAS的功能。随心所欲。此外，我们证实了在体外生长过程中研究的TAS分子的转录和翻译。我们测序分析了M. mycoides亚种的15个基因组。capri并揭示了所研究的TAS分布不均，从而表明该物种内TAS的动态得失。