Dooley M M, Halling S M, Doi R H
Biochim Biophys Acta. 1980 Nov 14;610(1):158-66. doi: 10.1016/0005-2787(80)90065-9.
Several, but not all, forms of bacillus subtilis RNA polymerase found in vegetative and sporulating cells can synthesize poly(A) x poly(U) in vitro. The vegetative delta-containing form of RNA polymerase (E delta) has little or no poly(A) x poly(U)-synthesizing activity, whereas RNA polymerase core (E) and sigma-containing core (E delta) both have significant activity. When purified vegetative delta factor was added to core, the core synthetic activity was reduced essentially to that of the vegetative enzyme E delta. When E sigma enzymes from vegetative and sporulating cells were compared for their salt sensitivity, it was found that the sporulation enzyme E sigma retained much more of its activity at 0.1 M KCl than the vegetative enzyme E sigma. Furthermore, when sporulation enzyme E delta 1 was compared with vegetative enzyme E sigma, it was found that the activity of the E sigma 1 form was much more resistant to high KCl concentrations than that of the vegetative E sigma form. These differences in enzyme activity, as affected by salt concentrations, suggest that the conformations of the sporulation E sigma and E delta 1 enzymes are different from that found in vegetative E sigma enzyme. These differences in conformation may be involved in selective gene expression during sporularion.
在营养细胞和芽孢形成细胞中发现的几种（但并非全部）枯草芽孢杆菌RNA聚合酶形式能够在体外合成聚（A）x聚（U）。含δ因子的营养型RNA聚合酶（Eδ）几乎没有或完全没有聚（A）x聚（U）合成活性，而RNA聚合酶核心（E）和含σ因子的核心（Eσ）都具有显著活性。当将纯化的营养型δ因子添加到核心中时，核心的合成活性基本上降低到营养型酶Eδ的水平。当比较来自营养细胞和芽孢形成细胞的Eσ酶的盐敏感性时，发现芽孢形成酶Eσ在0.1M KCl下比营养型酶Eσ保留了更多的活性。此外，当将芽孢形成酶Eδ1与营养型酶Eσ进行比较时，发现Eσ1形式的活性比营养型Eσ形式对高KCl浓度更具抗性。受盐浓度影响的这些酶活性差异表明，芽孢形成Eσ和Eδ1酶的构象与营养型Eσ酶不同。这些构象差异可能参与芽孢形成过程中的选择性基因表达。
