Miller H I
Cell. 1981 Jul;25(1):269-76. doi: 10.1016/0092-8674(81)90252-x.
Previous experiments have shown that the himA gene of E. coli specifies a protein that is required for bacteriophage lambda integration. lambda Forms clear plaques on himA mutants indicating a possible additional defect in the establishment of repression. We have tested the effects of a himA mutation on the establishment and maintenance of lambda repressor (cl) synthesis and on the synthesis of Int protein. The rate of synthesis of cl and Int after infection by lambda is severely reduced in a strain carrying a himA gene deletion. Synthesis of Int or repressor can occur in the himA- strain if the phage carry constitutive promoters for either the int gene or the cl gene. Maintenance of repression is unaffected by himA mutations as judged by repressor-stimulated transcription of PM fused to the lacZ gene. These results indicate that the himA gene participates in the regulation of the promoter sites specific of the establishment of lysogeny: PE for cl synthesis and PI, for Int production. Since the himA gene product is required also for lambda site-specific recombination, it appears that the himA gene regulates lambda lysogeny at several levels. I discuss the significance of this multilevel regulation to lambda development.
先前的实验表明，大肠杆菌的himA基因编码一种噬菌体λ整合所必需的蛋白质。λ在himA突变体上形成清亮噬菌斑，这表明在建立阻遏过程中可能存在其他缺陷。我们测试了himA突变对λ阻遏物（cl）合成的建立和维持以及Int蛋白合成的影响。在携带himA基因缺失的菌株中，λ感染后cl和Int的合成速率严重降低。如果噬菌体携带int基因或cl基因的组成型启动子，则himA-菌株中可以发生Int或阻遏物的合成。通过与lacZ基因融合的PM的阻遏物刺激转录判断，阻遏的维持不受himA突变的影响。这些结果表明，himA基因参与溶原性建立特异性启动子位点的调控：cl合成的PE和Int产生的PI。由于himA基因产物也是λ位点特异性重组所必需的，因此himA基因似乎在多个水平上调节λ溶原性。我讨论了这种多级调控对λ发育的意义。
