title: In vivo duplication of genetic elements by the formation of stem-loop DNA without an RNA intermediate.
abstract: Gene duplication through cDNA synthesis by reverse transcriptase is believed to have played an important role in the diversification of genomes during evolution. Here, we demonstrate that a genomic DNA sequence can be duplicated in vivo as a result of template switching. When an inverted repeat (IR) structure was inserted in a site downstream from a ColE1 plasmid origin of DNA replication, transformation of Escherichia coli cells with this plasmid resulted in the production of a new DNA fragment encompassing the region from the origin to the center of the IR structure. The structure of this DNA molecule is composed of a long stem-loop formed by a single-stranded DNA, in which the loop is formed by the IR structure. The DNA fragment is designated slDNA, for stem-loop DNA. The experiments in this study suggest that during DNA replication, template switching at the stem-loop structure formed by the IR structure gives rise to slDNA utilizing the nascent DNA strand or the parental strand as a template. The mechanistic implications of slDNA synthesis, and its possible roles in genome evolution, are discussed.
authors.affiliation: Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854.
authors.forename: A
authors.initials: A
authors.lastname: Ohshima
authors.forename: S
authors.initials: S
authors.lastname: Inouye
authors.forename: M
authors.initials: M
authors.lastname: Inouye
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000737:chemistry; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D005810:Multigene Family; D009690:Nucleic Acid Conformation; D010957:Plasmids; D013698:Templates, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004247:DNA