title: Isolation and characterization of host mutants defective in msDNA synthesis: role of ribonuclease H in msDNA synthesis.
abstract: 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.
authors.affiliation: Department of Microbiology, New York University Medical Center, New York 10016, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Lima
authors.forename: D
authors.initials: D
authors.lastname: Lim
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D004251:DNA Transposable Elements; D004277:DNA, Single-Stranded / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D016254:Mutagenesis, Insertional; D010957:Plasmids; D012329:RNA, Bacterial / Q000096:biosynthesis*; D016914:Ribonuclease H / Q000235:genetics / Q000378:metabolism*; D013753:Tetracycline Resistance / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D004251:DNA Transposable Elements; D004277:DNA, Single-Stranded; D012329:RNA, Bacterial; C058681:msDNA; D016914:Ribonuclease H