A superfamily of DNA transposons targeting multicopy small RNA genes

• Published in: PloS one 2013-07, Vol.8 (7), p.e68260
• Main Authors: Kojima, Kenji K, Jurka, Jerzy
• Format: Article
• Language: English
• Subjects: Alveolata; Amino Acid Motifs; Amino Acid Sequence; Animals; Base Sequence; Biology; Conservation; Conserved sequence; Copy number; DDE; Deoxyribonucleic acid; DNA; DNA Transposable Elements - genetics; Drosophila melanogaster; Evolution, Molecular; Gene Dosage; Gene sequencing; Gene transfer; Genes; Genomes; Heredity; Insects; Insertion; Molecular Sequence Data; Multigene Family; Mutagenesis, Insertional; Nitrous oxide; Nucleotide sequence; Proteins; Ribonucleic acid; Ribosomal RNA; RNA; RNA, Small Nuclear - chemistry; RNA, Small Nuclear - genetics; RNA, Small Nuclear - metabolism; RNA, Transfer, Ala - genetics; RNA, Transfer, Ala - metabolism; RNA, Transfer, Leu - genetics; RNA, Transfer, Leu - metabolism; rRNA; Sequence Alignment; snRNA; Terminal Repeat Sequences; Transfer RNA; Transposase; Transposases - chemistry; Transposases - genetics; Transposons; tRNA; Zebrafish
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0068260

Target-specific integration of transposable elements for multicopy genes, such as ribosomal RNA and small nuclear RNA (snRNA) genes, is of great interest because of the relatively harmless nature, stable inheritance and possible application for targeted gene delivery of target-specific transposable elements. To date, such strict target specificity has been observed only among non-LTR retrotransposons. We here report a new superfamily of sequence-specific DNA transposons, designated Dada. Dada encodes a DDE-type transposase that shows a distant similarity to transposases encoded by eukaryotic MuDR, hAT, P and Kolobok transposons, as well as the prokaryotic IS256 insertion element. Dada generates 6-7 bp target site duplications upon insertion. One family of Dada DNA transposons targets a specific site inside the U6 snRNA genes and are found in various fish species, water flea, oyster and polycheate worm. Other target sequences of the Dada transposons are U1 snRNA genes and different tRNA genes. The targets are well conserved in multicopy genes, indicating that copy number and sequence conservation are the primary constraints on the target choice of Dada transposons. Dada also opens a new frontier for target-specific gene delivery application.