Identification of the gene encoding DNA topoisomerase I from Candida albicans

A gene encoding a type I topoisomerase (TOP1) was isolated from Candida albicans, sequenced, and expressed in Saccharomyces cerevisiae. The TOP1 gene was identified from a C. albicans genomic library by hybridization with the product of a polymerase chain reaction with degenerate primer sets encoding regions conserved in other TOP1 genes. A clone containing an open reading frame of 2463 bp and predicted to encode a protein of 778 amino acids with sequence similarity to eukaryotic type I topoisomerases was identified. The C. albicans TOP1 gene restored camptothecin sensitivity and increased the topoisomerase activity in S. cerevisiae, indicating that the DNA fragment encodes a functional C. albicans topoisomerase I.