[Determination of the endonuclease activity encoded by retrotransposon]. / Endonukleaznaia aktivnost' retrotransposona Penelope.

Mobile element Penelope is mobilized in the course of hybrid dysgenesis in D. virilis. This element is also responsible for the activation of other unrelated families of TE occurring in the progeny of dysgenic crosses. Penelope elements have extremely variable structure and combine some properties of LINEs and LTR-containing elements. Penelope-like elements (PLEs) have been recently described in various organisms including fish species, rotifers and amoebae. Computer analysis enabled to predict the presence of reverse transcriptase domain in Penelope-encoded polyprotein as well as UvrC type endonuclease at the C-end of the element. It is noteworthy that none of the previously described retroelements was shown to contain such a nuclease. Multiple alignments revealed five conservative catalytic motifs and all conservative residues present in GIY-YIG endonuclease family within Penelope-encoded protein. Herein we have demonstrated that Penelope element isolated from D. virilis encodes functionally active endonuclease exhibiting some sequence-specificity to the sequence previously demonstrated to serve as Penelope genomic insertion site.

[The unusual mobile element Penelope and its behavior in distant Drosophila species]. / Neobychnyi mobil'nyi élement Penelope i ego povedenie v otdalennykh vidakh Drozofily.

The retroelement Penelope isolated from Drosophila virilis has a very unusual structure and codes for reverse transcriptase and an endonuclease belonging to the UvrC type. As shown previously, Penelope is a key element in induction of the hybrid dysgenesis syndrome described in D. virilis, which also involves mobilization of several unrelated mobile element families. Here we report a successful introduction of Penelope into the D. melanogaster genome by P element-mediated transformation. In the new host genome, Penelope is actively transcribed producing major transcript which coincides with that detected in dysgenic hybrids of D. virilis. In situ hybridization on D. melanogaster polytene chromosomes and Southern blotting revealed multiple transpositions of Penelope in the transformed D. melanogaster strains. We determined the structure of six Penelope copies inserted into D. melanogaster chromosomes. Some transformed D. melanogaster strains showed dysgenesis effects similar to those observed in hybrids from D. virilis dysgenic crosses.