Structure of the Drosophila HeT-A transposon: a retrotransposon-like element forming telomeres

• Published in: Chromosoma 1994-06, Vol.103 (3), p.215-224
• Main Authors: Danilevskaya, O, Slot, F, Pavlova, M, Pardue, M.L
• Format: Article
• Language: English
• Subjects: AIDS/HIV; Amino Acid Sequence; amino acid sequences; Animals; Base Sequence; Biological and medical sciences; Cell-Free System; Consensus Sequence; Drosophila melanogaster; Drosophila melanogaster - genetics; Fundamental and applied biological sciences. Psychology; genbank/u06920; genbank/u06921; genbank/u06947; genbank/x68130; genetic change; Genic rearrangement. Recombination. Transposable element; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; nucleotide sequences; open reading frames; Open Reading Frames - genetics; Protein Biosynthesis; Retroelements - genetics; retrotransposons; RNA, Messenger - biosynthesis; Sequence Homology, Nucleic Acid; Telomere - genetics; Transcription, Genetic; transposition; transposons
• ISSN: 0009-5915; 1432-0886
• DOI: 10.1007/BF00368015

Telomers of Drosophila appear to be very different from those of other organisms. A transposable element, HeT-A, plays a major role in forming telomeres and may be the sole structural element, since telomerase-generated repeats are not found. HeT-A transposes only to chromosome ends. It appears to be a retrotransoson but has novel structural features, which may be related to its telomere functions. A consensus sequence from cloned HeT-A elements defines an element of approximately 6 kb. The coding region has retrotransposon-like overlapping open reading frames (ORFs) with a -1 frameshift in a sequence resembling the frameshift region of the mammalian HIV-1 retrovirus. Both the HeT-A ORFs contain motifs suggesting RNA binding. HeT-A-specific features include a long non-coding region. 3' of the ORFs, which makes up about half of the element. This region has a regular array of imperfect sequence repeats and ends with oligo(A), marking the end of the element and suggesting a polyadenylated RNA transposition intermediate. This 3' repeat region may have a structural role in heterochromatin. The most distal part of each complete HeT-A on the chromosome, the region 5' of the ORFs, has unusual conserved features, which might produce a terminal structure for the chromosome.