title: Topoisomerase 2 is dispensable for the replication and segregation of small yeast artificial chromosomes (YACs).
abstract: DNA topoisomerases are thought to play a critical role in transcription, replication and recombination as well as in the condensation and segregation of sister duplexes during cell division. Here, we used high-resolution two-dimensional agarose gel electrophoresis to study the replication intermediates and final products of small circular and linear minichromosomes of Saccharomyces cerevisiae in the presence and absence of DNA topoisomerase 2. The results obtained confirmed that whereas for circular minichromosomes, catenated sister duplexes accumulated in the absence of topoisomerase 2, linear YACs were able to replicate and segregate regardless of this topoisomerase. The patterns of replication intermediates for circular and linear YACs displayed significant differences suggesting that DNA supercoiling might play a key role in the modulation of replication fork progression. Altogether, this data supports the notion that for linear chromosomes the torsional tension generated by transcription and replication dissipates freely throughout the telomeres.
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Cebrián
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Monturus
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: María-Luisa
authors.initials: ML
authors.lastname: Martínez-Robles
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Hernández
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: Dora B
authors.initials: DB
authors.lastname: Krimer
authors.affiliation: Department of Cell and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: Jorge B
authors.initials: JB
authors.lastname: Schvartzman
mesh_terms: D020090:Chromosome Segregation / Q000235:genetics* / Q000502:physiology*; D018244:Chromosomes, Artificial, Yeast / Q000235:genetics* / Q000502:physiology; D004261:DNA Replication / Q000235:genetics* / Q000502:physiology*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004270:DNA, Circular / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004278:DNA, Superhelical / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D016615:Telomere / Q000378:metabolism
chemical_list: D004270:DNA, Circular; D004271:DNA, Fungal; D004278:DNA, Superhelical; D029701:Saccharomyces cerevisiae Proteins; D004250:DNA Topoisomerases, Type II