Maamar Hédia, Raj Arjun, Dubnau David
Public Health Research Institute Center, New Jersey Medical School, 225 Warren Street, Newark, NJ 07103, USA.
Science. 2007 Jul 27;317(5837):526-9. doi: 10.1126/science.1140818. Epub 2007 Jun 14.
Random cell-to-cell variations in gene expression within an isogenic population can lead to transitions between alternative states of gene expression. Little is known about how these variations (noise) in natural systems affect such transitions. In Bacillus subtilis, noise in ComK, the protein that regulates competence for DNA uptake, is thought to cause cells to transition to the competent state in which genes encoding DNA uptake proteins are expressed. We demonstrate that noise in comK expression selects cells for competence and that experimental reduction of this noise decreases the number of competent cells. We also show that transitions are limited temporally by a reduction in comK transcription. These results illustrate how such stochastic transitions are regulated in a natural system and suggest that noise characteristics are subject to evolutionary forces.
在同基因群体中，基因表达的随机细胞间差异可导致基因表达的不同状态之间的转变。对于自然系统中的这些差异（噪声）如何影响此类转变，人们了解甚少。在枯草芽孢杆菌中，调控DNA摄取能力的蛋白质ComK中的噪声被认为会导致细胞转变为有能力的状态，即表达编码DNA摄取蛋白的基因。我们证明，comK表达中的噪声选择有能力的细胞，并且实验性降低这种噪声会减少有能力的细胞数量。我们还表明，转变在时间上受到comK转录减少的限制。这些结果说明了这种随机转变在自然系统中是如何受到调控的，并表明噪声特征受到进化力量的影响。
