Soheili Sara, Ghafourian Sobhan, Sekawi Zamberi, Neela Vasantha Kumari, Sadeghifard Nourkhoda, Taherikalani Morovat, Khosravi Afra, Ramli Ramliza, Hamat Rukman Awang
Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health sciences, Universiti Putra Malaysia, Serdang, Malaysia.
Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran.
Drug Des Devel Ther. 2015 May 8;9:2553-61. doi: 10.2147/DDDT.S77263. eCollection 2015.
The toxin-antitoxin (TA) system is a regulatory system where two sets of genes encode the toxin and its corresponding antitoxin. In this study, the prevalence of TA systems in independently isolated clinical isolates of Enterococcus faecium and Enterococcus faecalis was determined, the dominant TA system was identified, different virulence genes in E. faecium and E. faecalis were surveyed, the level of expression of the virulence and TA genes in normal and stress conditions was determined, and finally their associations with the TA genes were defined. Remarkably, the analysis demonstrated higBA and mazEF in all clinical isolates, and their locations were on chromosomes and plasmids, respectively. On the other hand, a quantitative analysis of TA and virulence genes revealed that the expression level in both genes is different under normal and stress conditions. The results obtained by anti-mazF peptide nucleic acids demonstrated that the expression level of virulence genes had decreased. These findings demonstrate an association between TA systems and virulence factors. The mazEF on the plasmids and the higBA TA genes on the chromosomes of all E. faecium and E. faecalis strains were dominant. Additionally, there was a decrease in the expression of virulence genes in the presence of anti-mazF peptide nucleic acids. Therefore, it is suggested that mazEF TA systems are potent and sensitive targets in all E. faecium and E. faecalis strains.
毒素-抗毒素（TA）系统是一种调控系统，其中两组基因分别编码毒素及其相应的抗毒素。在本研究中，测定了屎肠球菌和粪肠球菌独立分离临床分离株中TA系统的流行情况，鉴定了优势TA系统，调查了屎肠球菌和粪肠球菌中不同的毒力基因，测定了正常和应激条件下毒力基因和TA基因的表达水平，最后确定了它们与TA基因的关联。值得注意的是，分析表明所有临床分离株中均存在higBA和mazEF，它们的位置分别在染色体和质粒上。另一方面，对TA和毒力基因的定量分析表明，在正常和应激条件下，这两个基因的表达水平不同。抗mazF肽核酸获得的结果表明毒力基因的表达水平有所下降。这些发现证明了TA系统与毒力因子之间的关联。所有屎肠球菌和粪肠球菌菌株染色体上的higBA TA基因和质粒上的mazEF是优势基因。此外，在存在抗mazF肽核酸的情况下，毒力基因的表达有所下降。因此，建议mazEF TA系统是所有屎肠球菌和粪肠球菌菌株中有效的敏感靶点。
