Pays E, Donaldson D, Gilmour R S
Biochim Biophys Acta. 1979 Mar 28;562(1):112-30. doi: 10.1016/0005-2787(79)90131-x.
In the presence of Mn2+, globin mRNA can be transcribed into a partial RNA copy by Escherichia coli RNA polymerase. This process also occurs when the mRNA is transcribed together with chromatin. A fraction, at least, of the newly synthesized RNA copy (anti-globin RNA) can serve as a template for the synthesis of globin sequences of the same polarity as the original mRNA. This process is sufficient to explain the specific synthesis of a subset of the globin RNA on mouse foetal liver chromatin. It also accounts for the synthesis of double-stranded RNA sequence by E. coli RNA polymerase, on chromatin as well as on pure mRNA. Results are presented suggesting that the poly(A) tract of the mRNA could be preferentially transcribed. In the presence of Mg2+, the RNA-dependent transcription is strongly inhibited, as well as the synthesis of double-stranded RNA. Under these conditions, the transcription on chromatin appears to be largely DNA dependent, and the synthesis of globin sequences is completely asymmetric. Spermine (0.3 mM) seems to improve the specificity of transcription. The transcription of chromatin in vitro is thus largely dependent on the nature of the divalent cation present in the in the incubation mixture.
在Mn2+存在的情况下，大肠杆菌RNA聚合酶可将珠蛋白mRNA转录成部分RNA拷贝。当mRNA与染色质一起转录时，该过程也会发生。新合成的RNA拷贝（抗珠蛋白RNA）中至少有一部分可作为模板，用于合成与原始mRNA极性相同的珠蛋白序列。这一过程足以解释小鼠胎儿肝脏染色质上一部分珠蛋白RNA的特异性合成。它也解释了大肠杆菌RNA聚合酶在染色质以及纯mRNA上合成双链RNA序列的现象。研究结果表明，mRNA的聚（A）尾可能被优先转录。在Mg2+存在的情况下，RNA依赖性转录以及双链RNA的合成均受到强烈抑制。在这些条件下，染色质上的转录似乎很大程度上依赖于DNA，珠蛋白序列的合成完全不对称。精胺（0.3 mM）似乎可提高转录的特异性。因此，体外染色质的转录很大程度上取决于孵育混合物中存在的二价阳离子的性质。
