Skip to Main content Skip to Navigation
Journal articles

Mechanisms of Camptothecin Resistance by Human Topoisomerase I Mutations

Abstract : Human topoisomerase I relaxes superhelical tension associated with DNA replication, transcription and recombination by reversibly nicking one strand of duplex DNA and forming a covalent 3'-phosphotyrosine linkage. This enzyme is the sole target of the camptothecin family of anticancer compounds, which acts by stabilizing the covalent protein-DNA complex and enhancing apoptosis through blocking the advancement of replication forks. Mutations that impart resistance to camptothecin have been identified in several regions of human topoisomerase I. We present the crystal structures of two camptothecin-resistant forms of human topoisomerase I (Phe361Ser at 2.6A resolution and Asn722Ser at 2.3A resolution) in ternary complexes with DNA and topotecan (Hycamtin), a camptothecin analogue currently in widespread clinical use. While the alteration of Asn722 to Ser leads to the elimination of a water-mediated contact between the enzyme and topotecan, we were surprised to find that a well-ordered water molecule replaces the hydrophobic phenylalanine side-chain in the Phe361Ser structure. We further consider camptothecin-resistant mutations at seven additional sites in human topoisomerase I and present structural evidence explaining their possible impact on drug binding. These results advance our understanding of the mechanism of cell poisoning by camptothecin and suggest specific modifications to the drug that may improve efficacy.
Document type :
Journal articles
Complete list of metadata
Contributor : Philippe Pourquier Connect in order to contact the contributor
Submitted on : Tuesday, January 14, 2020 - 12:08:14 PM
Last modification on : Thursday, November 19, 2020 - 8:50:30 AM

Links full text




Jill Chrencik, Bart Staker, Alex Burgin, Philippe Pourquier, Yves Pommier, et al.. Mechanisms of Camptothecin Resistance by Human Topoisomerase I Mutations. Journal of Molecular Biology, Elsevier, 2004, 339 (4), pp.773-784. ⟨10.1016/j.jmb.2004.03.077⟩. ⟨inserm-02438638⟩



Record views