Structural organization characteristics of the DIP1 gene in Drosophila melanogaster strains mutant for the flamenco gene

• Published in: Russian journal of genetics 2007-01, Vol.43 (1), p.56-63
• Main Authors: Nefedova, L. N., Romanova, N. I., Kim, A. I.
• Format: Article
• Language: English
• Subjects: Drosophila melanogaster
• ISSN: 1022-7954; 1608-3369
• DOI: 10.1134/S1022795407010097

Molecular cloning of the DIP1 gene located in the 20A4-5 region has been performed from the following strains with the flamenco phenotype: flam super(SS) (SS) and flam super(MS) (MS) characterized by a high transposition rate of retrotransposon gypsy (mdg4), flam super(py) + (P) carrying the insertion of a construction based on the P element into the region of the flamenco gene, and flamenco super(+). The results of restriction analysis and sequencing cloned DNA fragments has shown that strains flam super(SS), flam super(MS) considerably differ from flam super(py) + (P), and flamenco super(+) in the structure of DIP1. Strains flam super(SS) and flam super(MS) have no DraI restriction site at position 1765 in the coding region of the gene, specifically, in the domain determining the signal of the nuclear localization of the DIP1 protein. This mutation has been found to consist in a nucleotide substitution in the recognition site of DraI restriction endonuclease, which is transformed from TTTAAA into TTTAAG and, hence, is not recognized by the enzyme. This substitution changes codon AAA into AAG and is translationally insignificant, because both triplets encode the same amino acid, lysine. The DIP1 gene of strains flam super(SS) and flam super(MS) has been found to contain a 182-bp insertion denoted IdSS (insertion in DIP1 strain SS); it is located in the second intron of the gene. The IdSS sequence is part of the open reading frame encoding the putative transposase of the mobile genetic element HB1 belonging to the Tc1/mariner family. This insertion is presumed to disturb the conformations of DNA and the chromosome, in particular, by forming loops, which alters the expression of DIP1 and, probably, neighboring genes. In strains flamenco super(+) and flam super(ipy) + (P), the IdSS insertion within the HB1 sequence is deleted. The deletion encompasses five C-terminal amino acid residues of the conserved domain and the entire C-terminal region of the putative HB1 transposase. The obtained data suggest that DIP1 is involved in the control of gypsy transpositions either directly or through interaction with other elements of the genome.