Nucleotide sequence analysis of the CDNA for rat DNA topoisomerase II

CDNA clones encoding the rat DNA topoisomerase II were isolated from rat testis CDNA library using a DNA probe synthesized by two sequential nested PCRs. The nucleotide sequence of the entire coding region and its deduced 1526 amino acid sequence showed that 80% nucleotides and 89% amino acids were identical with human HeLa DNA topoisomerase II gene (hTOP2). Approximately 1100 amino acids at the N-terminus shows 96.5% sequence identity, but C-terminus has only 65% homology. Rat DNA topoisomerase II gene (rTOP2) contains three functional domains responsible for ATPase activity, break-reunion activity, and complex stability and DNA binding activity like other eukaryotic TOP2. It also contains two putative nuclear targeting sequences and a leucine zipper motif and has highly charged species specific sequences at the C-terminus.