title: A P element has induced intron formation in Drosophila.
abstract: We report evidence supporting the hypothesis that some introns could be originated from transposable elements. In the Drosophila montium species subgroup, we recently described a novel example of domestication by the host genome of a P transposable element. The element is a unique truncated P sequence transcribed into a polyadenylated RNA encoding a putative 66-kDa transposition repressor-like protein. Here, we analyze the genomic modifications associated with this transition of a transposable element into a stationary gene that is useful for the host. Study of the transcription modalities of this neogene reveals that the new transcriptional unit harbors a de novo synthesis of a new exon and a new intron upstream of the original P sequence initiation site. The new exon was constructed from the genomic flanking sequence of the P sequence, whereas the first half of the new intron is composed of genomic flanking sequence and the second half is composed of P sequence. This domestication event has involved the capture of a new promoter. An investigation of a large number of species belonging to the melanogaster species group revealed that this P element domestication is restricted to the species of the montium subgroup and that the new exon-intron structure is present in at least three other species. From sequence data, we hypothesize that cryptic acceptor and donor splicing sites present on the P element and flanking sequences have been under selective constraints which have led to the emergence of a new intron.
authors.affiliation: Institut Jacques Monod, Université P. et M. Curie, Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Nouaud
authors.forename: B
authors.initials: B
authors.lastname: Boëda
authors.forename: L
authors.initials: L
authors.lastname: Levy
authors.forename: D
authors.initials: D
authors.lastname: Anxolabéhère
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA; D004330:Drosophila / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014158:Transcription, Genetic
chemical_list: D004247:DNA