Condensin is required for nonhistone protein assembly and structural integrity of vertebrate mitotic chromosomes.
The dramatic condensation of chromosomes that occurs during mitosis is widely thought to be largely controlled by a protein complex termed condensin. Here, we describe a conditional knockout of the condensin subunit ScII/SMC2 in chicken DT40 cells. In cells lacking this condensin subunit, chromosome condensation is delayed, but ultimately reaches near-normal levels. However, these chromosomes are structurally compromised. Kinetochores appear normal, but the localization of nonhistone proteins such as topoisomerase II and INCENP is aberrant. Both proteins also fail to partition into the chromosome scaffold fraction, which appears to be largely missing in the absence of condensin. Furthermore, the chromosomes lack structural integrity, as defined by an assay that tests the stability of the chromosomal higher-order structure. Thus, a major function of condensin is to promote the correct association of nonhistone proteins with mitotic chromosomes, and this is essential for establishment of a robust chromosome structure.
Hudson
Damien F
DF
Wellcome Trust Centre for Cell Biology, Institute of Cell, University of Edinburgh, Swann Building, King's Buildings, Mayfield Road, EH9 3JR, Edinburgh, United Kingdom.
Vagnarelli
Paola
P
Gassmann
Reto
R
Earnshaw
William C
WC
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002645:Chickens; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018390:Gene Targeting; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D008954:Models, Biological; D046912:Multiprotein Complexes; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes
D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D021122:Protein Subunits; C108312:condensin complexes; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II