Isolation and functional analysis of the 5'-flanking region of carrot top1beta gene coding for the beta isoform of DNA topoisomerase I.

We have isolated and functionally characterized the promoter region of the top1beta gene encoding carrot (Daucus carota) DNA topoisomerase Ibeta. The major transcription start site was mapped by primer extension analysis 164 nt upstream the ATG translation start codon. Sequence analysis of the 5'-upstream region of the gene revealed the presence of a canonical TATA-like box at position -35 bp and several cis-acting sequences, including a (CT)n element in the leader region of the gene, a myb-related motif and the Dof element NtBBF-1, which correlate with the inducible expression pattern of this gene.