title: Two variants of the Drosophila melanogaster retrotransposon gypsy (mdg4): structural and functional differences, and distribution in fly stocks.
abstract: Two variants of the Drosophila melanogaster retrotransposon gypsy were subjected to detailed structural and functional analysis. A series of hybrid constructs containing various combinations of "active" and "inactive" gypsy copies were tested for their ability to produce new DNA copies in cultured cells by means of reverse transcription. It was shown that the previously demonstrated variations in retrotranspositional activity are associated with either one or both of two amino acid substitutions at the beginning of ORF2. The first substitution is located at the boundary between the putative protease and reverse transcriptase domains and, hence, may influence the processing of the polyprotein. The other substitution may alter reverse transcriptase activity since it is located in the second of the seven conserved domains of the RT gene. To address the question of the evolutionary relationship between the two gypsy variants, their distribution was analyzed in among various fly stocks. Southern analysis revealed that all D. melanogaster strains studied so far contain the "inactive" gypsy variant, while the "active" copies are present only in some strains; most of the latter were established from flies recently isolated from natural populations. Finally, in stocks carrying the flamenco mutation the "active" gypsy variant is much more abundant than the "inactive" form. Possible scenarios for the orgin of the "active" form of gypsy are discussed.
authors.affiliation: V.A. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow.
authors.forename: N V
authors.initials: NV
authors.lastname: Lyubomirskaya
authors.forename: J B
authors.initials: JB
authors.lastname: Smirnova
authors.forename: O V
authors.initials: OV
authors.lastname: Razorenova
authors.forename: N N
authors.initials: NN
authors.lastname: Karpova
authors.forename: S A
authors.initials: SA
authors.lastname: Surkov
authors.forename: S N
authors.initials: SN
authors.lastname: Avedisov
authors.forename: A I
authors.initials: AI
authors.lastname: Kim
authors.forename: Y V
authors.initials: YV
authors.lastname: Ilyin
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000235:genetics*; D017344:Genes, Insect; D014644:Genetic Variation; D011994:Recombinant Proteins / Q000235:genetics*; D018626:Retroelements; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D011994:Recombinant Proteins; D018626:Retroelements; D014157:Transcription Factors; C110987:mdg4 protein (gypsy)