Cloning of Chinese hamster DNA topoisomerase I cDNA and identification of a single point mutation responsible for camptothecin resistance.

摘要: A camptothecin-resistant (DC3F/C-10) Chinese hamster cell line that contains a catalytically altered and camptothecin (CPT)-resistant DNA topoisomerase I (top 1) (Tanizawa, A., Pommier, Y. (1992) Cancer Res. 52, 1848-1854) the parent (DC3F) were used to compare top 1 mRNAs cDNAs. Northern blot analysis showed single 4.1-kilobase band without quantitative reduction between two lines. We have cloned sequenced DC3F DC3F/C-10 c-DNA are 3591 3626 base pair long, respectively, encode 767 amino acids. The homology of deduced acid sequences mouse or human 98.1 96.7, respectively. cDNAs from cells differ by point mutation (G A) which results in an change Gly505 Ser (Gly505-->Ser). G505 corresponds Gly503 cDNA is located 220 acids away presumed catalytic Tyr725. region highly conserved among all (plant ATH, vaccinia virus, Shope fibroma Drosophila, Saccharomyces cerevisiae, Schizosaccharomyces pombe, mouse, Human). Asp533 Gly this same has been shown confer CPT resistance for 1. protein with Gly505-->Ser was expressed bacteria resistant CPT, indicating involved resistance. Our suggest around plays important role interactions 1, DNA, CPT.