The Mycobacterium tuberculosis SigD sigma factor controls the expression of ribosome-associated gene products in stationary phase and is required for full virulence
The Mycobacterium tuberculosis SigD sigma factor controls the expression of ribosome-associated gene products in stationary phase and is required for full virulence
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DOI：
10.1111/j.1462-5822.2004.00454.x
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发表时间：
2005-02-01
影响因子：
3.4
通讯作者：
Bishai, WR
中科院分区：
文献类型：
--
作者：
Calamita, H;Ko, C;Bishai, WR
在感染期间，结核杆菌会暴露于多种环境条件，具体取决于疾病的阶段和严重程度。为了生存M结核病使用交替的σ因子来调节其基因表达以响应宿主环境的变化。为了更好地理解应激反应基因的调节方式，在M. CDC 1551菌株中，细胞质外σ因子基因sigD被缺失，随后被补充。结核DeltasigD突变菌株在丰富培养基中表现出与sigD互补和野生型CDC 1551菌株相同的体外生长速率。此外，在J774A.1巨噬细胞系中，突变、补充和野生型细菌之间的短期细胞内生长没有观察到差异。然而，与感染野生型细菌的巨噬细胞中观察到的水平相比，感染DeltasigD突变体的巨噬细胞中的肿瘤坏死因子（TNF）-α水平降低。在死亡时间研究中，与感染补充或野生型菌株的C3 H小鼠相比，感染DeltasigD突变体的C3 H小鼠表现出死亡延迟。尽管感染DeltasigD突变体的小鼠死亡率降低，但这些小鼠的肺和脾中的杆菌负荷与感染补充或野生型菌株的小鼠中观察到的相当。相对于野生型的DeltasigD突变体的微阵列分析显示，SigD指导一小组核糖体基因和三磷酸腺苷转运蛋白的表达，其表达通常在体外稳定期生长期间诱导。通过定量逆转录聚合酶链反应分析证实了这些基因的一个子集的表达改变。类似于共有序列AGAAAG-N16-20-CGTTAA的启动子样元件被发现在DeltasigD突变体中低表达的19个基因的上游，表明这可能是M.结核病SigD全酶，Esigma（D）.这些数据表明，M.结核病SigD σ因子控制通常在体外生长期间在稳定期表达的一小组核糖体基因的表达，并且sigD的丧失降低巨噬细胞TNF-α分泌以及M.小鼠结核感染。
During infection Mycobacterium tuberculosis is exposed to several environmental conditions depending on the stage and severity of the disease. To survive, M. tuberculosis uses alternate sigma factors to regulate its gene expression in response to the changing host environment. In order to better understand the way in which stress response genes are regulated, the extracytoplasmic sigma factor gene sigD was deleted and subsequently complemented in the CDC1551 strain of M. tuberculosis. The DeltasigD mutant strain exhibited an in vitro growth rate in rich medium identical to that of both the sigD-complemented and wild-type CDC1551 strains. Additionally, no differences were observed in short-term intracellular growth between the mutant, complemented, and wild-type bacteria within the J774A.1 macrophage cell line. However, tumour necrosis factor (TNF)-alpha levels in macrophages infected with the DeltasigD mutant were decreased as compared to levels observed in macrophages infected with the wild-type bacteria. In time-to-death studies, C3H mice infected with the DeltasigD mutant exhibited a mortality delay compared to those infected with either the complemented or wild-type strains. Although mice infected with the DeltasigD mutant died at a reduced rate, the bacillary loads in the lungs and spleen of these mice were comparable to those seen in mice infected with either the complemented or wild-type strains. Microarray analysis of the DeltasigD mutant relative to wild type revealed that SigD directs the expression of a small set of ribosomal genes and adenosine triphosphate transporters whose expression is normally induced during stationary phase growth in vitro. Altered expression of a subset of these genes was confirmed by quantitative reverse transcription polymerase chain reaction analysis. Promoter-like elements resembling the consensus sequence AGAAAG-N16-20-CGTTAA were found upstream of 19 of the genes underexpressed in the DeltasigD mutant suggesting this may be the recognition sequence for the M. tuberculosis SigD-holoenzyme, Esigma(D). These data indicate that the M. tuberculosis SigD sigma factor governs the expression of a small set of ribosomal genes typically expressed in stationary phase during in vitro growth and that loss of sigD reduces macrophage TNF-alpha secretion as well as the lethality of M. tuberculosis infection in mice.