[Effect of nucleocapsid on multimerization of gypsy structural protein Gag].

The structural protein (Gag) of the gypsy Drosophila retrovirus lacks matrix, but contains capsid and nucleocapsid domains. The Gag forms virus-like particles in a bacterial cell; besides, its capsid alone is able to form aggregates. However, aggregates assembled from the capsid were variable in size and displayed much less organization than particles formed by the whole Gag.

[The structural protein Gag of the gypsy retrovirus forms virus-like particles in the bacterial cell].

The amino acid sequence of the drosophila retrovirus MDG4 (gypsy) structural protein Gag does not contain a canonical motif known for the majority of vertebrate retroviruses. Moreover, the protein translation can theoretically begin with two separated initiation codons located within its unique open reading frame. We designed constructs for expression of two theoretically possible variants of Gag polypeptide and investigated an ability of the each product to form virus-like particles in the bacterial cell, i.

[Precise excision of long terminal repeats of the gypsy (mdg4) retrotransposon of Drosophila melanogaster detected in Escherichia coli cells is explained by its integrase function].

An Escherichia coli model system was developed to estimate the capacity of the integrase of the Drosophila melanogaster retrotransposon gypsy (mdg4) for precise excision of the long terminal repeat (LTR) and, hence, the entire gypsy. The gypsy retrotransposon was cloned in the form of a PCR fragment in the pBlueScript II KS+ (pBSLTR) vector, and the region of the second open reading frame (INT ORF2) of this element encoding integrase was cloned under the lacZ promoter in the pUC19 vector and then recloned in pACYC184 compatible with pBSLTR. The LTR was cloned in such a manner that its precise excision from the recombinant plasmid led to the restoration of the nucleotide sequence and the function of the ORF of the lacZ gene contained in the vector; therefore, it was detected by the appearance of blue colonies on a medium containing X-gal upon IPTG induction.

[Diversity of LTR retrotransposons and their role in genome reorganization].

Current views of retrotransposons possessing long terminal repeats (LTRs) are described. The existing classification and element types isolated by genome organization are considered. Experimental data are summarized to demonstrate that the replicative cycle of a retrotransposon is not restricted to a single cell and that LTR retrotransposons are transferred between somatic cells with a rate comparable with the element transposition rate within the genome of one cell.

[Retrotransposon gtwin: structural analysis and distribution in Drosophila melanogaster strains].

A search for noncanonical variants of the gypsy retrotransposon (MDG4) in the genome of the Drosophila melanogaster strain G32 led to the cloning of four copies of the poorly studied 7411-bp gtwin element. Sequence analysis showed that gtwin belongs to a family of endogeneous retroviruses, which are widespread in the Drosophila genome and have recently been termed insect erantiviruses. The gtwin retrotransposon is evolutionarily closest to MDG4, as evident from a good alignment of their nucleotide sequences including ORF1 (the pol gene) and ORF3 (the env gene), as well as the amino acid sequences of their protein products.

[Errantiviruses of Drosophila].

The view on Drosophila long terminal repeat (LTR) retrotransposons, which have three reading frames, as endogenous retroviruses or errantiviruses (ERVs, according to the latest ICTV nomenclature) is discussed. Data on the biology of ERVs and the mechanisms of their involvement in genetic instability of Drosophila are considered.

[Retrotransposon MDG4 and its role in genetic instability of a mutator strain of Drosophila melanogaster].

This article summarizes the results of a ten-year study of genetic instability of a mutator strain of Drosophila melanogaster caused by transposition of the gypsy retrotransposon. The results of other authors working with an analogous system are analyzed. Possible mechanisms are suggested for the interaction of gypsy with the cell gene flamenco that participates in transposition control of this mobile element.

[Retrotransposon mdg3 is transferred between somatic cells of unrelated species in coculture].

Since retrovirus-like particles of gypsy (mdg4) are capable of interspecific transfer, other Drosophila melanogaster gypsy-related retrotransposons were tested for this property. As a donor and a recipient, D. melanogaster and D.

[Mobile genetic element MDG4 (gypsy) in Drosophila melanogaster. Features of structure and regulation of transposition].

Distribution of two structural functional variants of the MDG4 (gypsy) mobile genetic element was examined in 44 strains of Drosophila melanogaster. The results obtained suggest that less transpositionally active MDG4 variant is more ancient component of the Drosophila genome. Using Southern blotting, five strains characterized by increased copy number of MDG4 with significant prevalence of the active variant over the less active one were selected for further analysis.

[Interlineage distribution and characteristics of the structure of two subfamilies of Drosophila melanogaster MDG4 (gypsy) retrotransposon].

The distribution of two variants of MDG4 (gypsy) was analyzed in several Drosophila melanogaster strains. Southern blot hybridization revealed the inactive variant of MDG4 in all strains examined and active MDG4 only in some of them. Most of the strains harboring the active MDG4 variant were recently isolated from natural populations.

[Trans-mobilization of deletion copies of the mdg3 retrotransposon in cultured cells of Drosophila].

A model system was studied that was associated with the selective amplification of shortened copies of the mdg3 retrotransposon in cultured cells of Drosophila melanogaster. While full-length mdg3 is present in all species phylogenetically closely related to D. melanogaster, the distribution of its deletion copy mdg3del was shown to be restricted only to D.