Newman A, Hayward R S
Mol Gen Genet. 1980 Feb;177(3):527-33. doi: 10.1007/BF00271493.
We provide evidence that, in terms of transcriptional organisation, the rpoBC operon carried by lambdarifd 18 accurately represents the corresponding region of the E. coli K12 chromosome. A restriction fragment of E. coli K12 chromosomal DNA carrying the genes rpoBC (encoding the beta and beta' subunits of RNA polymerase) and rplL (coding for ribosomal proteins L7/L12) was cloned in a lambda vector, and the resulting phage tested for gene expression. In common with the corresponding fragment of lambdarifd 18 DNA, the chromosomal fragment has no strong promoter for rplL or rpoBC transcription. Another new phage was constructed by adding, to the restriction fragment carrying the rplL rpoBC structural genes from lambdarifd 18, a sequence from the E. coli K12 chromosome which includes a promoter for these genes. As in lambdarifd 18 itself, this promoter is shared with rplJ but not with rplKA. The properties of the latter phage also show that the dominant rifampicin-resistance characteristic of lambdarifd 18 results from more than one mutation.
我们提供的证据表明，就转录组织而言，λrifd 18携带的rpoBC操纵子准确地代表了大肠杆菌K12染色体的相应区域。将携带rpoBC基因（编码RNA聚合酶的β和β'亚基）和rplL基因（编码核糖体蛋白L7/L12）的大肠杆菌K12染色体DNA限制性片段克隆到λ载体中，并对产生的噬菌体进行基因表达测试。与λrifd 18 DNA的相应片段一样，染色体片段没有用于rplL或rpoBC转录的强启动子。通过将来自大肠杆菌K12染色体的一个序列添加到携带来自λrifd 18的rplL rpoBC结构基因的限制性片段上，构建了另一种新的噬菌体，该序列包含这些基因的启动子。与λrifd 18本身一样，该启动子与rplJ共享，但不与rplKA共享。后一种噬菌体的特性还表明，λrifd 18的显性利福平抗性特征是由多个突变导致的。
