The complete Tirant transposable element in Drosophila melanogaster shows a structural relationship with retrovirus-like retrotransposons.
We have determined the structure and organization of Tirant, a retrotransposon of Drosophila melanogaster reported in literature to be responsible for four independent mutations. Tirant is a long terminal repeat (LTR) retrotransposon 8527bp long. It possesses three open reading frames (ORF) encoding Gag, Pol and Env proteins with a strong similarity with ZAM, a recently identified member of the gypsy class of retrovirus-like mobile elements. Molecular analysis of the Tirant genomic copies present in four D. melanogaster strains revealed that most of them are defective, non-autonomous elements that differ in the position and extension of the conserved internal portion. Defective elements lacking the Gag ORF but retaining the Env ORF are abundant in heterochromatin. Four discrete Tirant transcripts are observed during embryogenesis in the strain Oregon-R, the smaller of which, 1.8kb in size, originates from the splicing of a primary transcript and leads to a subgenomic RNA coding for the Env product.
Marsano
R M
RM
Istituto di Genetica, Università di Bari, Via Amendola 165/A, 70126, Bari, Italy.
Moschetti
R
R
Caggese
C
C
Lanave
C
C
Barsanti
P
P
Caizzi
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D004247:DNA / Q000737:chemistry / Q000235:genetics; D015342:DNA Probes; D004251:DNA Transposable Elements / Q000235:genetics*; D016208:Databases, Factual; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D015686:Gene Products, env / Q000235:genetics; D015683:Gene Products, gag / Q000235:genetics; D015698:Genomic Library; D017403:In Situ Hybridization; D016366:Open Reading Frames; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018626:Retroelements / Q000235:genetics*; D012469:Salivary Glands / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D015342:DNA Probes; D004251:DNA Transposable Elements; D015686:Gene Products, env; D015683:Gene Products, gag; D012333:RNA, Messenger; D018626:Retroelements; D004247:DNA