Williamson V M, Doi R H
Mol Gen Genet. 1978 May 3;161(2):135-41. doi: 10.1007/BF00274183.
A protein with a molecular weight of 21,000 daltons is found associated with a fraction of Bacillus subtilis RNA polymerase core. This protein (delta) does not react with antibody made against sigma factor and has a peptide map which is significantly different from sigma factor. At ratios of 2:1 to 4:1 (delta:holoenzyme) the delta displaces sigma factor completely from the core and associates in a 1:1 ratio with core to form delta-core. Under the same incubation conditions sigma factor at a ratio of 10:1 (sigma factor:delta-core) does not displace delta from the delta-core. The delta-core has much less activity as compared to holoenzyme on various DNA templates. However, sigma factor does stimulate the activity of delta-core enzyme under conditions of RNA synthesis. These observations and the results of others suggest that delta-core enzyme binds initially to specific DNA sites followed by delta release from the core-DNA complex and that the sigma factor binds to the core-DNA complex to initiate RNA synthesis. Thus both delta and sigma factors are required in a sequential fashion for specific transcription to occur in B subtilis.
发现一种分子量为21,000道尔顿的蛋白质与枯草芽孢杆菌RNA聚合酶核心的一部分相关联。这种蛋白质（δ）不与针对σ因子产生的抗体发生反应，并且其肽图与σ因子有显著差异。在2:1至4:1（δ:全酶）的比例下，δ完全从核心中取代σ因子，并以1:1的比例与核心结合形成δ-核心。在相同的孵育条件下，以10:1的比例（σ因子:δ-核心）的σ因子不会从δ-核心中取代δ。与全酶相比，δ-核心在各种DNA模板上的活性要低得多。然而，在RNA合成条件下，σ因子确实会刺激δ-核心酶的活性。这些观察结果以及其他研究结果表明，δ-核心酶最初与特定的DNA位点结合，随后δ从核心-DNA复合物中释放，并且σ因子与核心-DNA复合物结合以启动RNA合成。因此，在枯草芽孢杆菌中，特定转录的发生需要δ和σ因子按顺序发挥作用。
