title: Levels of Ycg1 Limit Condensin Function during the Cell Cycle.
abstract: During mitosis chromosomes are condensed to facilitate their segregation, through a process mediated by the condensin complex. Although several factors that promote maximal condensin activity during mitosis have been identified, the mechanisms that downregulate condensin activity during interphase are largely unknown. Here, we demonstrate that Ycg1, the Cap-G subunit of budding yeast condensin, is cell cycle-regulated with levels peaking in mitosis and decreasing as cells enter G1 phase. This cyclical expression pattern is established by a combination of cell cycle-regulated transcription and constitutive degradation. Interestingly, overexpression of YCG1 and mutations that stabilize Ycg1 each result in delayed cell-cycle entry and an overall proliferation defect. Overexpression of no other condensin subunit impacts the cell cycle, suggesting that Ycg1 is limiting for condensin complex formation. Consistent with this possibility, we find that levels of intact condensin complex are reduced in G1 phase compared to mitosis, and that increased Ycg1 expression leads to increases in both levels of condensin complex and binding to chromatin in G1. Together, these results demonstrate that Ycg1 levels limit condensin function in interphase cells, and suggest that the association of condensin with chromosomes must be reduced following mitosis to enable efficient progression through the cell cycle.
authors.affiliation: Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
authors.forename: Tyler W
authors.identifier: 0000-0001-5431-7087
authors.initials: TW
authors.lastname: Doughty
authors.affiliation: Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Arsenault
authors.affiliation: Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Benanti
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics*; D026921:Amino Acid Transport Systems, Neutral / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics; D002843:Chromatin / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics*; D002875:Chromosomes / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D007399:Interphase / Q000235:genetics; D008938:Mitosis / Q000235:genetics*; D046912:Multiprotein Complexes / Q000235:genetics*; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D002843:Chromatin; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D029701:Saccharomyces cerevisiae Proteins; C523288:Yct1 protein, S cerevisiae; C108312:condensin complexes; D000251:Adenosine Triphosphatases