Bistability in the Bacillus subtilis K-state (competence) system requires a positive feedback loop
Bistability in the Bacillus subtilis K-state (competence) system requires a positive feedback loop
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DOI：
10.1111/j.1365-2958.2005.04592.x
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发表时间：
2005-05-01
影响因子：
3.6
通讯作者：
Dubnau, D
中科院分区：
文献类型：
--
作者：
Maamar, H;Dubnau, D
转录激活因子ComK的高表达发生在枯草芽孢杆菌菌株168的稳定期培养物中的10-20%的细胞中。ComK驱动100多个基因的表达，这些基因构成了半休眠K状态，与孢子形成和营养生长不同。在这些被激活的基因中，有一些是允许遗传转化的基因。我们已经解决了ComK表达的双稳态的起源。我们表明，双稳态需要积极的自动调节在启动子的comK，但不是一个潜在的切换开关，其中ComK抑制ROK和ROK抑制启动子的comK。我们进一步解决了导致随机选择表达comK的细胞的噪声源。提出了一个修正的模型，comK表达的调节，部分解释了双稳态。
High expression of the transcriptional activator ComK occurs in 10-20% of the cells in stationary phase cultures of Bacillus subtilis strain 168. ComK drives the expression of more than 100 genes constituting the semidormant K-state, distinct from sporulation and vegetative growth. Among the genes so activated are those that permit competence for genetic transformation. We have addressed the origin of bistability in expression of ComK. We show that bistability requires positive autoregulation at the promoter of comK, but not a potential toggle switch, in which ComK represses the promoter of rok and Rok represses the promoter of comK. We further address the source of the noise that results in the stochastic selection of cells that will express comK. A revised model for the regulation of comK expression is proposed that partially explains bistability.