title: Mispaired rNMPs in DNA are mutagenic and are targets of mismatch repair and RNases H.
abstract: Numerous studies have shown that ribonucleoside monophosphates (rNMPs) are probably abundant among all nonstandard nucleotides occurring in genomic DNA. Therefore, it is important to understand to what extent rNMPs may alter genome integrity and what factors affect their stability. We developed oligonucleotide-driven gene correction assays in Escherichia coli and Saccharomyces cerevisiae to show that mispaired rNMPs embedded into genomic DNA, if not removed, serve as templates for DNA synthesis and produce a genetic change. We discovered that isolated mispaired rNMPs in chromosomal DNA are removed by the mismatch repair system in competition with RNase H type 2. However, a mismatch within an RNA-DNA heteroduplex region requires RNase H type 1 for removal. In the absence of mismatch repair and RNases H, ribonucleotide-driven gene modification increased by a factor of 47 in yeast and 77,000 in E. coli.
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta, Georgia, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shen
authors.forename: Kyung Duk
authors.initials: KD
authors.lastname: Koh
authors.forename: Bernard
authors.initials: B
authors.lastname: Weiss
authors.forename: Francesca
authors.initials: F
authors.lastname: Storici
mesh_terms: D020137:Base Pair Mismatch; D001483:Base Sequence; D053843:DNA Mismatch Repair; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics / Q000378:metabolism*; D016914:Ribonuclease H / Q000378:metabolism*; D012265:Ribonucleotides / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D029968:Escherichia coli Proteins; D009692:Nucleic Acid Heteroduplexes; D012265:Ribonucleotides; D029701:Saccharomyces cerevisiae Proteins; D016914:Ribonuclease H