title: Disruption of a conserved CAP-D3 threonine alters condensin loading on mitotic chromosomes leading to chromosome hypercondensation.
abstract: The condensin complex plays a key role in organizing mitotic chromosomes. In vertebrates, there are two condensin complexes that have independent and cooperative roles in folding mitotic chromosomes. In this study, we dissect the role of a putative Cdk1 site on the condensin II subunit CAP-D3 in chicken DT40 cells. This conserved site has been shown to activate condensin II during prophase in human cells, and facilitate further phosphorylation by polo-like kinase I. We examined the functional significance of this phosphorylation mark by mutating the orthologous site of CAP-D3 (CAP-D3(T1403A)) in chicken DT40 cells. We show that this mutation is a gain of function mutant in chicken cells; it disrupts prophase, results in a dramatic shortening of the mitotic chromosome axis, and leads to abnormal INCENP localization. Our results imply phosphorylation of CAP-D3 acts to limit condensin II binding onto mitotic chromosomes. We present the first in vivo example that alters the ratio of condensin I:II on mitotic chromosomes. Our results demonstrate this ratio is a critical determinant in shaping mitotic chromosomes.
authors.affiliation: From the Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052 and the Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia.
authors.forename: Muhammed
authors.initials: M
authors.lastname: Bakhrebah
authors.affiliation: From the Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052 and the Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: From the Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052 and the Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia.
authors.forename: Jeff R
authors.initials: JR
authors.lastname: Mann
authors.affiliation: From the Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052 and the Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Kalitsis
authors.affiliation: From the Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052 and the Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia damien.hudson@mcri.edu.au.
authors.forename: Damien F
authors.initials: DF
authors.lastname: Hudson
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics; D002645:Chickens; D002843:Chromatin / Q000235:genetics / Q000648:ultrastructure*; D002875:Chromosomes / Q000235:genetics* / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000235:genetics*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics* / Q000648:ultrastructure; D009154:Mutation; D010766:Phosphorylation; D013912:Threonine / Q000737:chemistry / Q000235:genetics
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C108312:condensin complexes; D013912:Threonine; D016203:CDC2 Protein Kinase; D000251:Adenosine Triphosphatases
keywords: CdkI, Condensin, Prophase, Mitosis, Chromosome Condensation; Cell Biology; Cell Division; Chromatin Structure; Chromosomes; Mitosis