Lima T M, Lim D
Department of Microbiology, New York University Medical Center, New York 10016, USA.
Plasmid. 1995 May;33(3):235-8. doi: 10.1006/plas.1995.1026.
In some Escherichia coli strains, a single-stranded DNA (msDNA) covalently linked to RNA is produced by a reverse transcriptase (RT) encoded by a genetic element called a retron. We have looked for host genes involved in msDNA synthesis. From screening of 10,000 mutants generated by Tn5 insertions, we obtained 3 chromosomal mutants defective msDNA synthesis. Analysis showed that all 3 mutants were affected in the gene for ribonuclease H (rnh). In rnh mutants, the reverse transcription products were heterogeneous with several sizes, smaller and bigger than the wild-type msDNA, showing that the reverse transcription is inhibited by the lack of RNase H activity. It also suggests that the RT recognizes the structure of msDNA for the termination of reverse transcription.
在一些大肠杆菌菌株中，一种与RNA共价连接的单链DNA（msDNA）是由一种名为反转录子的遗传元件所编码的逆转录酶（RT）产生的。我们已经寻找了参与msDNA合成的宿主基因。通过筛选由Tn5插入产生的10000个突变体，我们获得了3个msDNA合成缺陷的染色体突变体。分析表明，所有3个突变体的核糖核酸酶H（rnh）基因都受到了影响。在rnh突变体中，逆转录产物具有多种大小的异质性，比野生型msDNA小和大，这表明逆转录受到RNase H活性缺乏的抑制。这也表明RT识别msDNA的结构以终止逆转录。
