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  • The EMBO Journal (2007) 26, 3783 - 3793
  • doi:10.1038/sj.emboj.7601793

Published online: 26 July 2007

In vivo analysis of cohesin architecture using FRET in the budding yeast Saccharomyces cerevisiaeEMBO Open

John Mc Intyre1, Eric GD Muller2, Stefan Weitzer1,a, Brian E Snydsman2, Trisha N Davis2 and Frank Uhlmann1

  1. Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, London, UK
  2. Department of Biochemistry, University of Washington, Seattle, WA, USA

Correspondence to:

Frank Uhlmann, Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, UK. Tel.: +44 207 269 3024; Fax: +44 207 269 3258; E-mail: frank.uhlmann@cancer.org.uk

aPresent address: Institute of Molecular Biotechnology, 1030 Vienna, Austria

Received 16 March 2007; Accepted 18 June 2007

Cohesion between sister chromatids in eukaryotes is mediated by the evolutionarily conserved cohesin complex. Cohesin forms a proteinaceous ring, large enough to trap pairs of replicated sister chromatids. The circumference consists of the Smc1 and Smc3 subunits, while Scc1 is thought to close the ring by bridging the Smc (structural maintenance of chromosomes) ATPase head domains. Little is known about two additional subunits, Scc3 and Pds5, and about possible conformational changes of the complex during the cell cycle. We have employed fluorescence resonance energy transfer (FRET) to analyse interactions within the cohesin complex in live budding yeast. These experiments reveal an unexpected geometry of Scc1 at the Smc heads, and suggest that Pds5 plays a role at the Smc hinge on the opposite side of the ring. Key subunit interactions, including close proximity of the two ATPase heads, are constitutive throughout the cell cycle. This depicts cohesin as a stable molecular machine undergoing only transient conformational changes during binding and dissociation from chromosomes. Using FRET, we did not observe interactions between more than one cohesin complex in vivo.

  • Keywords:

    • chromosome segregation,
    • cohesin,
    • FRET,
    • S. cerevisiae,
    • Smc proteins

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The EMBO Journal is published by Nature Publishing Group on behalf of European Molecular Biology Organization