Curtis Thomas D, Takeuchi Ippei, Gram Lone, Knudsen Gitte M
Department of Biotechnology and Biomedicine, Technical University of Denmark, Matematiktorvet Bldg. 301, DK-2800 Kongens Lyngby, Denmark.
Toxins (Basel). 2017 Jan 13;9(1):31. doi: 10.3390/toxins9010031.
A major factor in the resilience of is the alternative sigma factor B (σ). Type II Toxin/Antitoxin (TA) systems are also known to have a role in the bacterial stress response upon activation via the ClpP or Lon proteases. Directly upstream of the σ operon in is the TA system , which can cleave mRNA at UACMU sites. In this study, we showed that the TA locus does not affect the level of persister formation during treatment with antibiotics in lethal doses, but exerts different effects according to the sub-inhibitory stress added. Growth of a Δ mutant was enhanced relative to the wildtype in the presence of sub-inhibitory norfloxacin and at 42 °C, but was decreased when challenged with ampicillin and gentamicin. In contrast to studies in , we found that the locus did not affect transcription of genes within the σ operon, but MazEF effected the expression of the σ-dependent genes and , with a 0.22 and 0.05 fold change, respectively, compared to the wildtype under sub-inhibitory norfloxacin conditions. How exactly this system operates remains an open question, however, our data indicates it is not analogous to the system of , suggesting a novel mode of action for MazEF in
某一因素在……的恢复力中起主要作用，即替代西格玛因子B（σ）。已知II型毒素/抗毒素（TA）系统在通过ClpP或Lon蛋白酶激活后在细菌应激反应中发挥作用。在……中，σ操纵子的直接上游是TA系统……，其可在UACMU位点切割mRNA。在本研究中，我们表明……TA基因座在致死剂量抗生素处理期间不影响持留菌形成水平，但根据添加的亚抑制应激发挥不同作用。在亚抑制浓度的诺氟沙星存在下以及在42℃时，Δ……突变体相对于野生型的生长增强，但在用氨苄西林和庆大霉素攻击时生长降低。与在……中的研究不同，我们发现……基因座不影响σ操纵子内基因的转录，但MazEF影响σ依赖性基因……和……的表达，与亚抑制诺氟沙星条件下的野生型相比，变化倍数分别为0.22和0.05。然而，该系统究竟如何运作仍是一个悬而未决的问题，不过，我们的数据表明它与……的系统不同，提示MazEF在……中存在一种新的作用模式
