Dmitrnev A D, Danilevskaia O N, Khesin R B
Mol Biol (Mosk). 1976 May-Jun;10(2):690-703.
The influence of mutations in structural genes of beta- and beta'-subunits of RNA polymerase upon the synthesis of these subunits in E. coli cells have been investigated. An amber-mutation ts22 in the beta-subunit gene decreases the intracellular concentration of this subunit and the rate of its synthesis. At the same time the concentration and the rate of beta'-subunit synthesis is increased. These facts suggest the compensating activation of the synthesis of RNA polymerase subunits that takes place under the conditions of deficiency in one of the subunits. Reversions, as well as more effective suppression of ts22 amber-mutation achieved by streptomycin addition or substitution of su2 by sul result in a rise in the concentration and the rate of beta-subunit formation. This is accompanied by a drop in the concentration and the role of beta'-subunit synthesis. tsX missense motation in the beta'-subunit gene alters the properties of the enzyme increasing at the same time the concentration and the rate of synthesis of both subunits, particularly at nonpermissive temperature. This points to an inversely proportional relationship between the rate of synthesis of RNA polymerase subunits and total intracellular activity of the enzyme. Extra subunits are rapidly degraded in ts22 and tsX mutants.
研究了RNA聚合酶β亚基和β'亚基结构基因突变对大肠杆菌细胞中这些亚基合成的影响。β亚基基因中的琥珀突变ts22降低了该亚基的细胞内浓度及其合成速率。与此同时，β'亚基的合成浓度和速率增加。这些事实表明，在其中一个亚基缺乏的条件下，会发生RNA聚合酶亚基合成的补偿性激活。回复突变，以及通过添加链霉素或用sul替代su2对ts22琥珀突变更有效的抑制，导致β亚基形成的浓度和速率增加。这伴随着β'亚基合成浓度和作用的下降。β'亚基基因中的tsX错义突变改变了酶的性质，同时增加了两个亚基的合成浓度和速率，特别是在非允许温度下。这表明RNA聚合酶亚基的合成速率与酶的总细胞内活性之间存在反比关系。在ts22和tsX突变体中，额外的亚基会迅速降解。
