title: Spatiotemporal dynamics of condensins I and II: evolutionary insights from the primitive red alga Cyanidioschyzon merolae.
abstract: Condensins are multisubunit complexes that play central roles in chromosome organization and segregation in eukaryotes. Many eukaryotic species have two different condensin complexes (condensins I and II), although some species, such as fungi, have condensin I only. Here we use the red alga Cyanidioschyzon merolae as a model organism because it represents the smallest and simplest organism that is predicted to possess both condensins I and II. We demonstrate that, despite the great evolutionary distance, spatiotemporal dynamics of condensins in C. merolae is strikingly similar to that observed in mammalian cells: condensin II is nuclear throughout the cell cycle, whereas condensin I appears on chromosomes only after the nuclear envelope partially dissolves at prometaphase. Unlike in mammalian cells, however, condensin II is confined to centromeres in metaphase, whereas condensin I distributes more broadly along arms. We firmly establish a targeted gene disruption technique in this organism and find, to our surprise, that condensin II is not essential for mitosis under laboratory growth conditions, although it plays a crucial role in facilitating sister centromere resolution in the presence of a microtubule drug. The results provide fundamental insights into the evolution of condensin-based chromosome architecture and dynamics.
authors.affiliation: Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hirano
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002503:Centromere / Q000235:genetics; D020090:Chromosome Segregation; D032461:Chromosomes, Plant / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D008938:Mitosis / Q000235:genetics*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D000461:Rhodophyta / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D000251:Adenosine Triphosphatases