Effect of dam methylation on Tn5 transposition.
Effect of dam methylation on Tn5 transposition.
复制标题
dam 甲基化对 Tn5 转座的影响。
DOI：
10.1016/0022-2836(88)90377-4
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发表时间：
1988
影响因子：
5.6
通讯作者：
Reznikoff,WS
中科院分区：
文献类型：
--
作者：
Yin,JC;Krebs,MP;Reznikoff,WS
通过分析宿主（大肠杆菌）和元件中的突变来研究去甲基化对Tn5转座的影响。野生型元件以更高的频率转座，并在adam−宿主中显示出更高水平的转座酶表达。在编码转座酶的转录物的启动子区域中进行突变。转座和转座酶水平从这些突变体是独立的宿主甲基化系统。RNA量的测量支持这一假设，即去甲基化通过调节转座酶基因转录起始的频率对Tn5转座产生影响。由于转座酶水平增加时Tn5转座增加，在正常浓度下，转座酶的量是决定Tn5转座频率的限速因素。Tn5的插入序列之一IS 50的转座对去甲基化也很敏感，除了调节转录起始外，去甲基化还直接或间接地抑制转座酶对IS 50序列的利用。因此，去甲基化可以影响转座酶的表达和其作用的DNA底物。
The effect ofdammethylation on Tn5transposition was investigated by analyses of mutations in the host (Escherichia coli) and the element. Wild-type elements transposed at a higher frequency and showed higher levels of transposase expression in adam−host. Mutations were made in the promoter region of the transcript that codes for the transposase. Transposition and transposase levels from these mutants were independent of the host methylation system. Measurements of the amount of RNA support the hypothesis thatdammethylation exerts its effect on Tn5transposition by modulating the frequency of transcriptional initiation of the transposase gene. Since Tn5transposition increases when the transposase levels increase, at normal concentrations the amount of transposase is a rate-limiting factor that determines the transposition frequency of Tn5. Transposition of IS50, one of the insertion sequences that consistutes Tn5, is also sensitive todammethylation by a second mechanism in addition to that of modulating transcriptional initiation,dammethylation, either directly or indirectly, inhibits the usage of IS50sequences by the transposase. Thus,dammethylation can affect both the expression of the transposase and the DNA substrate upon which it acts.