Klier A, Fouet A, Débarbouillé M, Kunst F, Rapoport G
Unité de Biochimie Microbienne, Institut Pasteur, Paris, France.
Mol Microbiol. 1987 Sep;1(2):233-41. doi: 10.1111/j.1365-2958.1987.tb00517.x.
The sacR regulatory region, which modulates the expression of sacB, the structural gene for levansucrase, was separated into two parts: an upstream region which carries a constitutive promoter and a downstream region which carries a palindromic structure. Three types of fusions were constructed in which the aphA3 gene coding for kanamycin resistance of Streptococcus faecalis was placed downstream from different deleted sacR regions. Other fusions were constructed by inserting a promoter from phage SPO1 upstream from the sacB gene and part of the sacA region. A third kind of fusion was constructed in which the palindromic structure was flanked by a heterologous promoter and a heterologous structural gene. After introduction of these fusions into the chromosomal DNA of mutants affected in sacB regulation, it was possible to reveal different targets for the regulatory genes sacU, sacQ and sacS: the sacU and sacQ genes act on a region located near or just upstream from the promoter, and the sacS gene, which is involved in the induction process, acts on the palindromic structure.
蔗糖酶调节区（sacR）可调控果聚糖蔗糖酶的结构基因sacB的表达，该调节区被分为两部分：一个上游区域，带有一个组成型启动子；一个下游区域，带有一个回文结构。构建了三种融合体，其中编码粪肠球菌卡那霉素抗性的aphA3基因位于不同缺失的sacR区域下游。通过将噬菌体SPO1的启动子插入sacB基因和部分sacA区域的上游，构建了其他融合体。构建了第三种融合体，其中回文结构两侧是一个异源启动子和一个异源结构基因。将这些融合体导入受sacB调节影响的突变体的染色体DNA后，有可能揭示调节基因sacU、sacQ和sacS的不同作用靶点：sacU和sacQ基因作用于位于启动子附近或紧上游的一个区域，而参与诱导过程的sacS基因作用于回文结构。
