Albrechtsen H, Hammer-Jespersen K, Munch-Petersen A, Fiil N
Mol Gen Genet. 1976 Jul 23;146(2):139-45. doi: 10.1007/BF00268082.
Strains with an amber, polar mutation in the dra1 gene have been isolated. The mutation was introduced into a set of isogenic strains, wild type or with concurrent regulatory mutations, and further characterized by suppression and heat inactivation experiments. The effect of the polar dra mutation on the three remaining genes of the deo operon, the tpp, drm and pup genes, was determined by estimating the enzyme levels in the various dra-mutants. The effect was found to be non-coordinate, indicating the formation in the cells of two types of transcripts: A tetracistronic unit, containing the message from all four genes, and a dicistronic unit, covering the two distal genes only.
已分离出在dra1基因中存在琥珀色极性突变的菌株。该突变被引入一组同基因菌株中，这些菌株为野生型或同时存在调控突变，并通过抑制和热失活实验进行进一步表征。通过估计各种dra突变体中的酶水平，确定了极性dra突变对deo操纵子其余三个基因（tpp、drm和pup基因）的影响。发现这种影响是非协同的，这表明细胞中形成了两种类型的转录本：一种是包含来自所有四个基因信息的四顺反子单元，另一种是仅覆盖两个远端基因的双顺反子单元。
