Abstract

Emergence of multidrug resistant strains and extremely drug resistant strains of Mycobacterium tuberculosis is due to its ability to form persister cells. The formation of persister cells is assumed to be triggered due to the presence of large number of toxin–antitoxin (TA) systems in its genome. Mtb genome encodes 47 VapBC TA systems. In this work, we aim to biochemically characterize VapC46 toxin of the VapBC46 TA operon from Mycobacterium tuberculosis. Heterologous expression of VapC46 in E. coli is shown to exhibit bacteriostasis and toxicity alters the surface morphology of the E. coli cells. VapC46 is shown to possess ribonuclease activity in a magnesium-dependent manner. Using FRET and pull down assay, VapC46 is shown to interact with VapB46 antitoxin. A model of VapC46 is shown to resemble PIN domain family of proteins and reveals the putative active site required for its ribonuclease activity.

中文翻译：

---

结核分枝杆菌VapC46毒素的生化特性。

摘要

结核分枝杆菌的多重耐药菌株和极强耐药菌株的出现归因于其形成持久性细胞的能力。持久性细胞的形成被认为是由于其基因组中存在大量毒素-抗毒素（TA）系统而触发的。Mtb基因组编码47个VapBC TA系统。在这项工作中，我们旨在生化表征结核分枝杆菌VapBC46 TA操纵子的VapC46毒素。VapC46在大肠杆菌中的异源表达显示出抑菌作用，并且毒性改变了大肠杆菌的表面形态细胞。显示VapC46以镁依赖性方式具有核糖核酸酶活性。使用FRET和下拉测定法，显示VapC46与VapB46抗毒素相互作用。VapC46的模型显示类似于PIN域的蛋白质，并揭示了其核糖核酸酶活性所需的推定活性位点。