Role of P27-P55 operon from Mycobacterium tuberculosis in the resistance to toxic compounds
Role of P27-P55 operon from Mycobacterium tuberculosis in the resistance to toxic compounds
复制标题
DOI：
10.1186/1471-2334-11-195
复制
发表时间：
2011-07-16
影响因子：
3.7
通讯作者：
Bigi, Fabiana
中科院分区：
文献类型：
--
作者：
Bianco, Maria V.;Blanco, Federico C.;Bigi, Fabiana
背景：P27-P55(IprG-Rv1410c)操纵子对人类结核病的病原体结核分枝杆菌在小鼠体内感染后的存活至关重要。P55编码一个外排泵，已被证明使耻垢分枝杆菌和牛分枝杆菌对几种药物产生抗药性，而P27编码一种甘露糖化糖蛋白，以前被描述为调节对分枝杆菌的免疫反应的抗原。本研究的目的是确定P27-P55操纵子编码的蛋白对结核分枝杆菌对有毒化合物的抗性和细胞壁完整性的个体贡献。方法：为了检测P27-P55操纵子H37Rv突变株对孔雀绿、十二烷基硫酸钠、溴化乙锭和一线抗结核药物的敏感性，该菌株与野生型菌株和一组互补菌株在有和没有这些药物的情况下进行培养。结果：突变菌株对孔雀石绿的脱色速度快于野生型菌株，对孔雀石绿和溴化乙锭均敏感，对一线抗结核药物异烟肼和乙胺丁醇敏感。泵抑制剂利血平逆转了结核分枝杆菌对溴化乙锭的耐药性。这些结果表明，P27-P55通过一种类似外排泵的机制发挥作用。此外，P27-P55操纵子的缺失使结核分枝杆菌对十二烷基硫酸钠敏感，这表明这两种蛋白的缺乏会导致细菌细胞壁通透性的改变。重要的是，P27和P55都需要恢复突变体中的野生型表型。结论：结果清楚地表明，P27和P55在保护细胞壁和将有毒物质从细胞外转移的过程中存在功能上的联系。
Background: The P27-P55 (IprG-Rv1410c) operon is crucial for the survival of Mycobacterium tuberculosis, the causative agent of human tuberculosis, during infection in mice. P55 encodes an efflux pump that has been shown to provide Mycobacterium smegmatis and Mycobacterium bovis BCG with resistance to several drugs, while P27 encodes a mannosylated glycoprotein previously described as an antigen that modulates the immune response against mycobacteria. The objective of this study was to determine the individual contribution of the proteins encoded in the P27-P55 operon to the resistance to toxic compounds and to the cell wall integrity of M. tuberculosis.Method: In order to test the susceptibility of a mutant of M. tuberculosis H37Rv in the P27-P55 operon to malachite green, sodium dodecyl sulfate, ethidium bromide, and first-line antituberculosis drugs, this strain together with the wild type strain and a set of complemented strains were cultivated in the presence and in the absence of these drugs. In addition, the malachite green decolorization rate of each strain was obtained from decolorization curves of malachite green in PBS containing bacterial suspensions.Results: The mutant strain decolorized malachite green faster than the wild type strain and was hypersensitive to both malachite green and ethidium bromide, and more susceptible to the first-line antituberculosis drugs: isoniazid and ethambutol. The pump inhibitor reserpine reversed M. tuberculosis resistance to ethidium bromide. These results suggest that P27-P55 functions through an efflux-pump like mechanism. In addition, deletion of the P27-P55 operon made M. tuberculosis susceptible to sodium dodecyl sulfate, suggesting that the lack of both proteins causes alterations in the cell wall permeability of the bacterium. Importantly, both P27 and P55 are required to restore the wild type phenotypes in the mutant.Conclusions: The results clearly indicate that P27 and P55 are functionally connected in processes that involve the preservation of the cell wall and the transport of toxic compounds away from the cells.