Clarke S, Mandelstam J
Department of Biochemistry, University of Oxford, UK.
J Gen Microbiol. 1987 Sep;133(9):2371-80. doi: 10.1099/00221287-133-9-2371.
A mutation, spo-87, in the spo0J locus of Bacillus subtilis allows appreciable transcription of spoIIA, spoIID and spoIIG and later operons, even though most of the cells are morphologically blocked at stage 0 and the incidence of heat-resistant spores is about 1 per 10(4) cells. This mutation therefore appears to disengage the genetic control of sporulation from the morphological changes to which it should be connected. spoIIA and spoIIG are transcribed independently of one another. However, the products of both operons are needed for the activation of spoIID which occurs later. This indicates a convergence of parallel pathways of operon expression. We have also shown that nonsense mutations in spoIIAC (which codes for a sigma factor of RNA polymerase) prevent transcription of spoIID; by contrast, missense mutations in the same gene allow transcription of spoIID.
枯草芽孢杆菌spo0J位点的一个突变体spo - 87，即使大多数细胞在形态上被阻滞在0期，且耐热孢子的发生率约为每10⁴个细胞中有1个，仍能使spoIIA、spoIID和spoIIG以及后续操纵子进行可观的转录。因此，这个突变似乎使芽孢形成的遗传控制与本应与之相关的形态变化脱钩。spoIIA和spoIIG彼此独立转录。然而，两个操纵子的产物都是后期发生的spoIID激活所必需的。这表明操纵子表达的平行途径存在汇聚。我们还表明，spoIIAC（编码RNA聚合酶的一个sigma因子）中的无义突变会阻止spoIID的转录；相比之下，同一基因中的错义突变则允许spoIID转录。
