Tabor C W, Tabor H, Xie Q W
Proc Natl Acad Sci U S A. 1986 Aug;83(16):6040-4. doi: 10.1073/pnas.83.16.6040.
We have obtained Escherichia coli mutants lacking spermidine synthase (putrescine aminopropyltransferase) and have found that the mutated gene (speE) is located immediately upstream from the gene coding for S-adenosylmethionine decarboxylase (speD); these genes are located at 2.7 minutes on the E. coli chromosome. Both genes are present in a 1795-base-pair fragment of E. coli DNA that was cloned into pBR322. Deletion of 105 bases upstream of speE caused a coordinate loss of both activities, indicating that speE and speD constitute a single operon. speE and speD have also been cloned separately in a high-expression vector; strains carrying these plasmids overproduce the respective enzymes.
我们已获得缺乏亚精胺合酶（腐胺氨基丙基转移酶）的大肠杆菌突变体，并发现突变基因（speE）位于编码S-腺苷甲硫氨酸脱羧酶（speD）的基因紧邻上游；这些基因位于大肠杆菌染色体的2.7分钟处。这两个基因存在于克隆到pBR322中的一段1795个碱基对的大肠杆菌DNA片段中。speE上游105个碱基的缺失导致两种活性协同丧失，表明speE和speD构成一个单一操纵子。speE和speD也已分别克隆到一个高表达载体中；携带这些质粒的菌株过量产生各自的酶。
