Insertion sequence inversions mediated by ectopic recombination between terminal inverted repeats

• Published in: PloS one Vol. 5; no. 12; p. e15654
• Main Authors: Ling, Alison, Cordaux, Richard
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.12.2010; Public Library of Science (PLoS)
• Subjects: Bacteria; Base Sequence; Biodiversity and Ecology; Biology; Bordetella; Bordetella bronchiseptica; Bordetella pertussis; Chromosome Inversion; Culex pipiens; Deoxyribonucleic acid; DNA; DNA - genetics; DNA Transposable Elements; Drosophila simulans; Environmental Sciences; Eukaryotes; Evolution; Gene sequencing; Genome; Genomes; Genomic Instability; Genomics; Homologous recombination; Homology; Insects; Insertion; Insertion sequences; Inversions; Molecular Sequence Data; Nucleotide sequence; Phylogeny; Prokaryotes; Promoter Regions, Genetic; Recombination, Genetic; Sequence Homology, Nucleic Acid; Sequence Inversion; Shigella; Stability; Terminal Repeat Sequences; Transposons; Trends; Whooping cough; Wolbachia; Wolbachia - genetics; France
• DOI: 10.1371/journal.pone.0015654
• ISSN: 1932-6203

Transposable elements are widely distributed and diverse in both eukaryotes and prokaryotes, as exemplified by DNA transposons. As a result, they represent a considerable source of genomic variation, for example through ectopic (i.e. non-allelic homologous) recombination events between transposable element copies, resulting in genomic rearrangements. Ectopic recombination may also take place between homologous sequences located within transposable element sequences. DNA transposons are typically bounded by terminal inverted repeats (TIRs). Ectopic recombination between TIRs is expected to result in DNA transposon inversions. However, such inversions have barely been documented. In this study, we report natural inversions of the most common prokaryotic DNA transposons: insertion sequences (IS). We identified natural TIR-TIR recombination-mediated inversions in 9% of IS insertion loci investigated in Wolbachia bacteria, which suggests that recombination between IS TIRs may be a quite common, albeit largely overlooked, source of genomic diversity in bacteria. We suggest that inversions may impede IS survival and proliferation in the host genome by altering transpositional activity. They may also alter genomic instability by modulating the outcome of ectopic recombination events between IS copies in various orientations. This study represents the first report of TIR-TIR recombination within bacterial IS elements and it thereby uncovers a novel mechanism of structural variation for this class of prokaryotic transposable elements.