DNA Topoisomerase II Mutant of Saccharomyces cerevisiae: Topoisomerase II is Required for Segregation of Daughter Molecules at the Termination of DNA Replication

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 81; no. 9; pp. 2616 - 2620
• Main Authors: DiNardo, Stephen, Voelkel, Karen, Sternglanz, Rolf
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 01.05.1984; National Acad Sciences
• Subjects: Cell Cycle; Chromosomes; Dimers; DNA; DNA Replication; DNA Topoisomerases, Type I - genetics; Molecules; Monomers; Mother cells; Mutation; Nucleic Acid Conformation; Phenotype; Phenotypes; Plasmids; Saccharomyces cerevisiae - genetics; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.81.9.2616

A temperature-sensitive DNA topoisomerase II mutant of the yeast Saccharomyces cerevisiae has been identified. Genetic analysis shows that a single recessive nuclear mutation is responsible for both temperature-sensitive growth and enzymatic activity. Thus, topoisomerase II is essential for viability and the mutation is most probably in the structural gene. Experiments with synchronized mutant cells show that at the nonpermissive temperature cells can undergo one, and only one, round of DNA replication. These cells are arrested at medial nuclear division. Analysis of 2-μ m plasmid DNA from these cells shows it to be in the form of multiply intertwined catenated dimers. The results suggest that DNA topoisomerase II is necessary for the segregation of chromosomes at the termination of DNA replication.