Smits Wiep Klaas, Eschevins Caroline C, Susanna Kim A, Bron Sierd, Kuipers Oscar P, Hamoen Leendert W
Groningen Biomolecular Sciences and Biotechnology Institute, Department of Genetics, University of Groningen, Kerklaan 30, 9751 NN Haren, the Netherlands.
Mol Microbiol. 2005 May;56(3):604-14. doi: 10.1111/j.1365-2958.2005.04488.x.
In Bacillus subtilis competence for genetic transformation develops only in a subpopulation of cells in an isogenic culture. The molecular mechanisms underlying this phenotypic heterogeneity are unknown. In this study, we stepwise simplify the signal transduction cascade leading to competence, yielding a strain devoid of all regulatory inputs for this process that have been identified so far. We demonstrate that auto-stimulation of ComK, the master regulator for competence development, is essential and in itself can be sufficient to generate a bistable expression pattern. We argue that transcriptional regulation determines the threshold of ComK to initiate the auto-stimulatory response, and that the basal level of ComK (in a wild-type strain governed by MecA-mediated proteolytic control) determines the fraction of cells that reach this threshold, and thus develop competence.
在枯草芽孢杆菌中，遗传转化能力仅在同基因培养物中的亚群细胞中形成。这种表型异质性背后的分子机制尚不清楚。在本研究中，我们逐步简化导致感受态的信号转导级联反应，得到了一种菌株，该菌株对于此过程而言，目前已确定的所有调控输入均不存在。我们证明，ComK（感受态发育的主调控因子）的自刺激是必不可少的，其本身就足以产生双稳态表达模式。我们认为，转录调控决定了ComK启动自刺激反应的阈值，而ComK的基础水平（在由MecA介导的蛋白水解控制的野生型菌株中）决定了达到该阈值并因此形成感受态的细胞比例。
