Structure of the Drosophila DNA topoisomerase I gene and expression of messages with different lengths in the 3' untranslated region

Sheryl D. Brown, Claire X. Zhang, Alice D. Chen, Tao Shih Hsieh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The nucleotide sequence of the Drosophila DNA topoisomerase I gene (top1) has been determined. Structurally, top1 consists of eight exons and seven introns. The top1 coding region contains a new class of opa repeats, encoding clusters of serine residues instead of glutamine repeats usually seen in Drosophila genes of the neurogenic loci. A unique feature of top1 is the developmental switch of its transcripts: a heterogeneous population of transcripts ranging from 3.8 to 4.2 kb seen maximally at 0-2 h of embryogenesis and a 5.2-kb transcript maximal at 6-12h of embryonic development. The transcripts expressed in the 0-2-h embryo have been shown as maternal storage products specific to ovarian tissues. RACE analysis shows that whereas the 6-12-h transcripts have a single site for polyadenylation, there are at least 12 different sites for poly(A) addition to the 0-2-h transcripts. An additional intron specific for the maternal storage transcripts appears in some of the 0-2-h transcripts. No significant heterogeneity at the 5' end of the top1 transcripts is seen. Sequence searches have revealed a number of regulatory sequences for potential translational control in the 3' untranslated region.

Original languageEnglish
Pages (from-to)195-203
Number of pages9
Issue number2
Publication statusPublished - 12 May 1998
Externally publishedYes


  • Development
  • Genome
  • Polyadenylation sites
  • Structural analysis

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