Expression of VjbR under nutrient limitation conditions is regulated at the post-transcriptional level by specific acidic pH values and urocanic acid.
Expression of VjbR under nutrient limitation conditions is regulated at the post-transcriptional level by specific acidic pH values and urocanic acid.
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DOI：
10.1371/journal.pone.0035394
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Sieira R
中科院分区：
文献类型：
--
作者：
Arocena GM;Zorreguieta A;Sieira R
VjbR是LuxR同源物，其调节许多基因的转录，包括兼性细胞内病原体流产布鲁氏菌的重要毒力决定因子。这种转录因子属于参与称为群体感应的细胞-细胞通信过程的调节因子家族，其使细菌能够通过监测自身产生的自诱导分子的浓度来响应细胞群体密度的变化。与几乎所有其他LuxR型蛋白质不同，VjbR与DNA结合，并在没有任何自诱导信号的情况下激活转录。为了研究布鲁氏菌诱导VjbR介导的转录激活的机制，并确定如何防止VjbR靶基因的不适当时空表达，我们专注于研究vjbR本身的表达。通过测定与布鲁氏菌细胞内生活方式相关的不同参数，我们确定了一组触发VjbR蛋白表达的限制性条件。这种条件需要两种不同性质的信号的融合：5.5的特定pH值和尿刊酸的存在，尿刊酸是一种参与布鲁氏菌毒力和代谢之间联系的代谢物。此外，我们还观察到尿刊酸，pH值依赖的RibH 2和VirB 7，两个额外的细胞内生存相关蛋白的布鲁氏菌的表达。启动子活性的分析和mRNA水平的测定表明，诱导VjbR，RibH 2和VirB 7表达的尿刊酸依赖性机制在转录后水平起作用。两者合计，我们的研究结果支持一个模型，即布鲁氏菌诱导VjbR介导的转录，通过调节VjbR的表达，以响应与宿主内遇到的环境变化相关的特定信号。
VjbR is a LuxR homolog that regulates transcription of many genes including important virulence determinants of the facultative intracellular pathogen Brucella abortus. This transcription factor belongs to a family of regulators that participate in a cell-cell communication process called quorum sensing, which enables bacteria to respond to changes in cell population density by monitoring concentration of self produced autoinducer molecules. Unlike almost all other LuxR-type proteins, VjbR binds to DNA and activates transcription in the absence of any autoinducer signal. To investigate the mechanisms by which Brucella induces VjbR-mediated transcriptional activation, and to determine how inappropriate spatio-temporal expression of the VjbR target genes is prevented, we focused on the study of expression of vjbR itself. By assaying different parameters related to the intracellular lifestyle of Brucella, we identified a restricted set of conditions that triggers VjbR protein expression. Such conditions required the convergence of two signals of different nature: a specific pH value of 5.5 and the presence of urocanic acid, a metabolite involved in the connection between virulence and metabolism of Brucella. In addition, we also observed an urocanic acid, pH-dependent expression of RibH2 and VirB7, two additional intracellular survival-related proteins of Brucella. Analysis of promoter activities and determination of mRNA levels demonstrated that the urocanic acid-dependent mechanisms that induced expression of VjbR, RibH2, and VirB7 act at the post-transcriptional level. Taken together, our findings support a model whereby Brucella induces VjbR-mediated transcription by modulating expression of VjbR in response to specific signals related to the changing environment encountered within the host.
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影响因子：
4.5
作者：
Starr, Tregei;Ng, Tony W.;Celli, Jean
通讯作者：
Celli, Jean
影响因子：
3.6
作者：
O'Callaghan, D;Cazevieille, C;Ramuz, M
通讯作者：
Ramuz, M
影响因子：
3.6
作者：
Sieira, R;Comerci, DJ;Ugalde, RA
通讯作者：
Ugalde, RA
影响因子：
3.7
作者：
Ruy Bonomi, Hernan;Ines Marchesini, Maria;Alberto Goldbaum, Fernando
通讯作者：
Alberto Goldbaum, Fernando
DOI：
10.1084/jem.20030088
发表时间：
2003-08-18
期刊：
The Journal of experimental medicine
影响因子：
--
作者：
Celli J;de Chastellier C;Franchini DM;Pizarro-Cerda J;Moreno E;Gorvel JP
通讯作者：
Gorvel JP