Hoppel, a P-like element without introns: a P-element ancestral structure or a retrotranscription derivative?
An in silico search for P-transposable-element-related sequences in the Drosophila melanogaster genome allowed us to detect sequences that are similar to P-element transposases. These sequences are located in the central region of 3.4-kb Hoppel elements, a class II transposon. Polymerase chain reaction (PCR) analysis of the insertional polymorphism revealed that these elements are mobile. The 3.4-kb elements are the longest copies of this family ever found. They contain an open reading frame that is long enough to encode a transposase, suggesting that the 3.4-kb elements are the full-length copies of the Hoppel family. Multiple alignments of several P-element transposases from different species and the Hoppel-element-encoded peptide showed that all of the P-element introns and the 5' region of the transposase are absent from the Hoppel sequence. Sequence analysis combined with reverse transcriptase PCR analysis showed that the 3.4-kb Hoppel elements are intronless. P and Hoppel not only share similar amino acid sequences but also have terminal inverted repeats of the same length (31 bp), and their excision footprints present a similar structure, which suggests that their transposases are functionally very similar. Thus, we propose that the Hoppel element family be included in the P-element superfamily. Two evolutionary scenarios are discussed considering the presence /absence of introns within the P-element superfamily.
Reiss
Daphne
D
Institut Jacques Monod, UMR 7592 Dynamique du Génome et Evolution CNRS, Universités P. et M. Curie, D. Diderot, Paris, France. reiss@ijm.jussieu.fr
Quesneville
Hadi
H
Nouaud
Danielle
D
Andrieu
Olivier
O
Anxolabehere
Dominique
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000235:genetics; D019143:Evolution, Molecular; D007438:Introns; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D018626:Retroelements; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D017931:DNA Primers; D018626:Retroelements