The TOP2 gene of Trypanosoma brucei: a single-copy gene that shares extensive homology with other TOP2 genes encoding eukaryotic DNA topoisomerase II.

A mixed oligonucleotide probe containing sequences encoding a septapeptide found in yeast, Drosophila and human DNA topoisomerase II was used to screen a genomic library of Trypanosoma brucei. A positive was obtained, and nucleotide sequencing shows that the entire gene encoding DNA topoisomerase II of this organism, TbrTOP2, resides within the T. brucei insert of the clone. A single open reading frame of 1221 triplet codons starting from the first ATG was identified; the amino acid sequence deduced from it is highly homologous to other eukaryotic DNA topoisomerase II and corresponds to a 137-kDa polypeptide. Analysis of restriction endonuclease digests of T. brucei DNA by blot hybridization following gel electrophoresis indicates that TbrTOP2 is a single-copy gene.