Molecular and genetic analysis of condensin function in vertebrate cells.
We engineered mutants into residues of SMC2 to dissect the role of ATPase function in the condensin complex. These residues are predicted to be involved in ATP binding or hydrolysis and in the Q-loop, which is thought to act as a mediator of conformational changes induced by substrate binding. All the engineered ATPase mutations resulted in lethality when introduced into SMC2 null cells. We found that ATP binding, but not hydrolysis, is essential to allow stable condensin association with chromosomes. How SMC proteins bind and interact with DNA is still a major question. Cohesin may form a ring structure that topologically encircles DNA. We examined whether condensin behaves in an analogous way to its cohesin counterpart, and we have generated a cleavable form of biologically active condensin with PreScission protease sites engineered into the SMC2 protein. This has allowed us to demonstrate that topological integrity of the SMC2-SMC4 heterodimer is not necessary for the stability of the condensin complex in vitro or for its stable association with mitotic chromosomes. Thus, despite their similar molecular organization, condensin and cohesin exhibit fundamental differences in their structure and function.
Hudson
Damien F
DF
Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom. damien.hudson@mcri.edu.au
Ohta
Shinya
S
Freisinger
Tina
T
Macisaac
Fiona
F
Sennels
Lau
L
Alves
Flavia
F
Lai
Fan
F
Kerr
Alastair
A
Rappsilber
Juri
J
Earnshaw
William C
WC
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins; D002645:Chickens; D002875:Chromosomes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D006868:Hydrolysis; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; C490381:SMC2 protein, human; C108312:condensin complexes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases