title: Rad52-independent accumulation of joint circular minichromosomes during S phase in Saccharomyces cerevisiae.
abstract: We investigated the formation of X-shaped molecules consisting of joint circular minichromosomes (joint molecules) in Saccharomyces cerevisiae by two-dimensional neutral/neutral gel electrophoresis of psoralen-cross-linked DNA. The appearance of joint molecules was found to be replication dependent. The joint molecules had physical properties reminiscent of Holliday junctions or hemicatenanes, as monitored by strand displacement, branch migration, and nuclease digestion. Physical linkage of the joint molecules was detected along the entire length of the minichromosome and most likely involved newly replicated sister chromatids. Surprisingly, the formation of joint molecules was found to be independent of Rad52p as well as of other factors associated with a function in homologous recombination or in the resolution of stalled replication intermediates. These findings thus imply the existence of a nonrecombinational pathway(s) for the formation of joint molecules during the process of DNA replication or minichromosome segregation.
authors.affiliation: Institute of Cell Biology, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
authors.forename: Ralf Erik
authors.initials: RE
authors.lastname: Wellinger
authors.forename: Primo
authors.initials: P
authors.lastname: Schär
authors.forename: Jose M
authors.initials: JM
authors.lastname: Sogo
mesh_terms: D015825:Chromosomes, Fungal; D004261:DNA Replication / Q000502:physiology; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004706:Endodeoxyribonucleases / Q000378:metabolism; D046911:Macromolecular Substances; D051721:Rad52 DNA Repair and Recombination Protein; D016196:S Phase / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D004706:Endodeoxyribonucleases; C037106:endodeoxyribonuclease NdeI; D015252:Deoxyribonucleases, Type II Site-Specific; C035571:endodeoxyribonuclease VII