Ifuku O, Haze S, Kishimoto J, Koga N, Yanagi M, Fukushima S
Shiseido Research Center, Yokohama, Japan.
Biosci Biotechnol Biochem. 1993 May;57(5):760-5. doi: 10.1271/bbb.57.760.
We analyzed mutation points of the biotin operon from biotin-overproducing mutants of Escherichia coli resistant to two biotin analogs, actithiazic acid and 5-(2-thienyl)-valeric acid, by DNA sequencing. The biotin operons cloned from these mutants were classified into three groups. One point mutation, which was a GC-->AT change within the operator overlapping the -10 region of the rightward (bioB) promoter, was considered to result in disruption of operator structure and enhancement of promoter activity. Two other point mutations, which were both GC-->AT changes just before and after the initiation codon of the bioB gene, were considered to activate the translation efficiency. These mutations significantly accelerated the biotin-forming activity from dethiobiotin in cell-free extracts.
我们通过DNA测序分析了来自对两种生物素类似物（放线噻唑酸和5-（2-噻吩基）-戊酸）具有抗性的大肠杆菌生物素高产突变体的生物素操纵子的突变点。从这些突变体中克隆的生物素操纵子被分为三组。一个点突变，即发生在与向右（bioB）启动子的-10区域重叠的操纵子内的GC→AT变化，被认为导致操纵子结构破坏并增强启动子活性。另外两个点突变，分别是在bioB基因起始密码子之前和之后的GC→AT变化，被认为激活了翻译效率。这些突变显著加速了无细胞提取物中由脱硫生物素形成生物素的活性。
