文章基本信息

标题：DGR mutagenic transposition occurs via hypermutagenic reverse transcription primed by nicked template RNA
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作者：Santa S. Naorem ; Jin Han ; Shufang Wang 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：47
页码：E10187-E10195
DOI：10.1073/pnas.1715952114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Diversity-generating retroelements (DGRs) are molecular evolution machines that facilitate microbial adaptation to environmental changes. Hypervariation occurs via a mutagenic retrotransposition process from a template repeat ( TR ) to a variable repeat ( VR ) that results in adenine-to-random nucleotide conversions. Here we show that reverse transcription of the Bordetella phage DGR is primed by an adenine residue in TR RNA and is dependent on the DGR-encoded reverse transcriptase (bRT) and accessory variability determinant (Avd ), but is VR -independent. We also find that the catalytic center of bRT plays an essential role in site-specific cleavage of TR RNA for cDNA priming. Adenine-specific mutagenesis occurs during reverse transcription and does not involve dUTP incorporation, indicating it results from bRT-catalyzed misincorporation of standard deoxyribonucleotides. In vivo assays show that this hybrid RNA-cDNA molecule is required for mutagenic transposition, revealing a unique mechanism of DNA hypervariation for microbial adaptation.
关键词：diversity-generating retroelements ; bacteriophage ; Bordetella ; retrotransposition ; hypervariation