Effects of abasic sites and DNA single-strand breaks on prokaryotic RNA polymerases.
Effects of abasic sites and DNA single-strand breaks on prokaryotic RNA polymerases.
复制标题
无碱基位点和 DNA 单链断裂对原核 RNA 聚合酶的影响。
DOI：
10.1073/pnas.90.14.6601
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发表时间：
1993
影响因子：
11.1
通讯作者：
Doetsch,PW
中科院分区：
文献类型：
--
作者：
Zhou,W;Doetsch,PW
脱碱基位点被认为是最常发生的细胞DNA损伤，并且是自发产生的，或者是对DNA的化学或辐射损伤的结果。与存在于DNA聚合酶上的无碱基位点的影响的丰富信息相反，关于这些病变如何与RNA聚合酶相互作用的信息知之甚少。一个在体外转录系统被用来确定无碱基位点和单链断裂对转录延伸的影响。DNA模板构建含有单一的脱碱基位点或切口放置在独特的位置下游从两个不同的启动子和转录的SP6和大肠杆菌RNA聚合酶。SP6 RNA聚合酶最初停滞在无碱基位点，随后有效地绕过这些病变。E. coli RNA聚合酶也绕过了脱碱基位点。相反，在脱碱基位点引入的单链断裂完全阻断了两种RNA聚合酶的进展。全长序列分析表明，SP6和E.大肠杆菌RNA聚合酶主要（如果不是唯一的话）插入与脱碱基位点相对的腺嘌呤残基。这一发现表明，脱碱基位点在体内转录水平上可能具有高度致突变性。
Abasic sites are thought to be the most frequently occurring cellular DNA damage and are generated spontaneously or as the result of chemical or radiation damage to DNA. In contrast to the wealth of information that exists on the effects of abasic sites on DNA polymerases, very little is known about how these lesions interact with RNA polymerases. An in vitro transcription system was used to determine the effects of abasic sites and single-strand breaks on transcriptional elongation. DNA templates were constructed containing single abasic sites or nicks placed at unique locations downstream from two different promoters and were transcribed by SP6 and Escherichia coli RNA polymerases. SP6 RNA polymerase is initially stalled at abasic sites with subsequent, efficient bypass of these lesions. E. coli RNA polymerase also bypassed abasic sites. In contrast, single-strand breaks introduced at abasic sites completely blocked the progression of both RNA polymerases. Sequence analysis of full-length transcripts revealed that SP6 and E. coli RNA polymerases insert primarily, if not exclusively, adenine residues opposite to abasic sites. This finding suggests that abasic sites may be highly mutagenic in vivo at the level of transcription.