Zheng Chengkun, Zhao Xigong, Zeng Ting, Cao Manman, Xu Jiali, Shi Guolin, Li Jinquan, Chen Huanchun, Bei Weicheng
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China.
FEMS Microbiol Lett. 2017 Jul 3;364(12). doi: 10.1093/femsle/fnx126.
Toxin-antitoxin (TA) systems are small genetic elements that are widely prevalent in the genomes of bacteria and archaea. These modules have been identified in various bacteria and proposed to play an important role in bacterial physiology and virulence. However, their presence in the genomes of Actinobacillus species has received no attention. In this study, we describe the identification of four type II TA systems in Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia. Reverse transcription PCR analysis revealed that the genes encoding the toxin and antitoxin are co-transcribed. Overexpression of each toxin inhibited the growth of Escherichia coli, and the toxic effect could be counteracted by its cognate antitoxin. The pull-down experiments demonstrated that each toxin interacts with its cognate antitoxin in vivo. The promoter activity assays showed that each antitoxin could autoregulate either positively or negatively the TA operon transcription. In addition, the APJL_0660/0659 TA system is present in half of the detected serovars of A. pleuropneumoniae, while the others are present in all. Collectively, we identified four type II TA systems in A. pleuropneumoniae, and this study has laid the foundation for further functional study of these TA systems.
毒素-抗毒素（TA）系统是广泛存在于细菌和古菌基因组中的小遗传元件。这些模块已在多种细菌中被鉴定出来，并被认为在细菌生理学和毒力中发挥重要作用。然而，它们在放线杆菌属物种基因组中的存在尚未受到关注。在本研究中，我们描述了在猪胸膜肺炎放线杆菌（猪胸膜肺炎的病原体）中鉴定出四种II型TA系统。逆转录PCR分析表明，编码毒素和抗毒素的基因是共转录的。每种毒素的过表达均抑制大肠杆菌的生长，且其毒性作用可被相应的抗毒素抵消。下拉实验表明，每种毒素在体内都与其相应的抗毒素相互作用。启动子活性分析表明，每种抗毒素可正向或负向自动调节TA操纵子的转录。此外，APJL_0660/0659 TA系统存在于一半检测到的猪胸膜肺炎放线杆菌血清型中，而其他系统则存在于所有血清型中。我们总共在猪胸膜肺炎放线杆菌中鉴定出四种II型TA系统，本研究为这些TA系统的进一步功能研究奠定了基础。
