Regulation of the Mycobacterium tuberculosis mce1 operon
Regulation of the Mycobacterium tuberculosis mce1 operon
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DOI：
10.1128/jb.188.2.441-449.2006
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发表时间：
2006-01-01
影响因子：
3.2
通讯作者：
Riley, LW
中科院分区：
文献类型：
--
作者：
Casali, N;White, AM;Riley, LW
在鼠感染模型中，结核分枝杆菌mce1操纵子突变体诱发异常肉芽肿反应，导致不受控制的复制和未能进入持续状态。在这项研究中，我们证明，mce1基因可以转录为一个13基因的多顺反子的消息，包括Rv0166 Rv0178。定量逆转录酶PCR和免疫印迹分析表明，在体外生长过程中表达的mce1基因和蛋白质，但显着下调从小鼠巨噬细胞分离的细胞内杆菌。GntR转录调节因子的FadR亚家族的同源物Rv0165c（命名为Mce1R）位于上游，并从操纵子分化转录。为了研究该基因是否在调节mce1表达中起作用，我们建立了一个M。结核mce1R缺失突变体。在体外对数生长期间，与野生型中的表达相比，Delta mce1R中的mce1操纵子基因的表达没有差异。然而，在从小鼠巨噬细胞分离的杆菌中，Δ mce1R中mce1基因的表达显著较高。此外，mce 1 R的过表达导致mce 1基因的抑制。这些数据表明，Mce1R是一种负调节剂，其在细胞内起作用以抑制Mce1操纵子的表达。我们建议，Mce1R促进组织化肉芽肿形成所需的Mce1产物的平衡时间表达，这对宿主具有保护作用，也是M的持久性所必需的。结核
In the murine model of infection, a Mycobacterium tuberculosis mce1 operon mutant elicits an aberrant granulomatous response, resulting in uncontrolled replication and failure to enter a persistent state. In this study, we demonstrate that the mce1 genes can be transcribed as a 13-gene polycistronic message encompassing Rv0166 to Rv0178. Quantitative reverse transcriptase PCR and immunoblot analyses revealed that the mce1 genes and proteins are expressed during in vitro growth but are significantly down-regulated in intracellular bacilli isolated from murine macrophages. A homologue of the FadR subfamily of GntR transcriptional regulators, Rv0165c (designated Mce1R), lies upstream and is divergently transcribed from the operon. To investigate whether this gene plays a role in regulation of mce1 expression, we created an M. tuberculosis mce1R deletion mutant. There was no difference in expression of mce1 operon genes in Delta mce1R compared to expression in the wild type during logarithmic growth in vitro. However, in bacilli isolated from murine macrophages, expression of mce1 genes was significantly higher in Delta mce1R. In addition, overexpression of mce1R resulted in repression of the mce1 genes. These data demonstrate that Mce1R is a negative regulator that acts intracellularly to repress expression of the mce1 operon. We propose that Mce1R facilitates balanced temporal expression of the mce1 products required for organized granuloma formation, which is both protective to the host and necessary for the persistence of M. tuberculosis.