Eukaryotic DNA topoisomerase I reaction is topology dependent

• Published in: Nucleic acids research Vol. 16; no. 14B; pp. 7071 - 7085
• Main Authors: Camilloni, G, Di Martino, E, Caserta, M, di Mauro, E
• Format: Journal Article
• Language: English
• Published: England 25.07.1988
• Subjects: Alcohol Dehydrogenase - genetics; DNA Topoisomerases, Type I - metabolism; DNA, Circular - metabolism; DNA, Superhelical - metabolism; Eukaryotic Cells; Genes, Immunoglobulin; Immunoglobulin kappa-Chains; In Vitro Techniques; Kinetics; Nucleic Acid Conformation; Plasmids; Structure-Activity Relationship; Triticum aestivum
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/16.14.7071

The effects of supercoiling on the topoisomerization reaction by eukaryotic DNA topoisomerases I have been analyzed. The systems used were: DNA topoisomerase I from wheat germ, chicken erythrocyte and calf thymus on a 2.3 kb DNA fragment which encompasses the immunoglobulin kappa-light chain (L kappa) promoter of the mouse plasmacytoma MPC11; S. cerevisiae DNA topoisomerase I on a 2.2 kb DNA fragment from the same organism which encompasses the regulatory and the coding region of the ADH II gene; wheat germ DNA topoisomerase I on the plasmid pUC18. It was found in every system that lack of torsional stress prevents topoisomerization of the substrate. A simple regulatory model of DNA topoisomerase I function, based on topological considerations, is presented.