Débarbouillé M, Schwartz M
Mol Gen Genet. 1980;178(3):589-95. doi: 10.1007/BF00337865.
Some of the previously described malT-lacZ fusion strains (Débarbouillé and Schwartz, 1979) produce very low amounts of beta-galactosidase activity and hence grow poorly on lactose. Spontaneous mutants growing faster on lactose have been isolated. Some of the mutations map in, or close to, the promoter of the hybrid gene. They lead to an increased production of the hybrid proteins, which then become detectable on polyacrylamide gels. This effect is cis dominant. When the mutations, called malTq, are transduced into a malT+ background the resulting transductants express the three maltose operons in a partially constitutive way. The malTq mutations therefore represent a new type of constitutive mutation. Their existence provides further evidence for the previously proposed model of positive regulation in the maltose regulon. In addition they should facilitate the purification of the malT product, and the identification of the malT promoter on the DNA.
一些先前描述的malT-lacZ融合菌株（Débarbouillé和Schwartz，1979）产生的β-半乳糖苷酶活性非常低，因此在乳糖上生长不良。已经分离出在乳糖上生长更快的自发突变体。一些突变位于杂交基因的启动子内或其附近。它们导致杂交蛋白产量增加，然后在聚丙烯酰胺凝胶上变得可检测到。这种效应是顺式显性的。当将称为malTq的突变转导到malT+背景中时，产生的转导子以部分组成型方式表达三个麦芽糖操纵子。因此，malTq突变代表了一种新型的组成型突变。它们的存在为先前提出的麦芽糖调节子中的正调控模型提供了进一步的证据。此外，它们应该有助于纯化malT产物，并在DNA上鉴定malT启动子。
