title: Condensin Smc2-Smc4 Dimers Are Flexible and Dynamic.
abstract: Structural maintenance of chromosomes (SMC) protein complexes, including cohesin and condensin, play key roles in the regulation of higher-order chromosome organization. Even though SMC proteins are thought to mechanistically determine the function of the complexes, their native conformations and dynamics have remained unclear. Here, we probe the topology of Smc2-Smc4 dimers of the S. cerevisiae condensin complex with high-speed atomic force microscopy (AFM) in liquid. We show that the Smc2-Smc4 coiled coils are highly flexible polymers with a persistence length of only ∼ 4 nm. Moreover, we demonstrate that the SMC dimers can adopt various architectures that interconvert dynamically over time, and we find that the SMC head domains engage not only with each other, but also with the hinge domain situated at the other end of the ∼ 45-nm-long coiled coil. Our findings reveal structural properties that provide insights into the molecular mechanics of condensin complexes.
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft 2628 CJ, the Netherlands.
authors.forename: Jorine M
authors.initials: JM
authors.lastname: Eeftens
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft 2628 CJ, the Netherlands.
authors.forename: Allard J
authors.initials: AJ
authors.lastname: Katan
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Kschonsak
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Hassler
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft 2628 CJ, the Netherlands.
authors.forename: Liza
authors.initials: L
authors.lastname: de Wilde
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft 2628 CJ, the Netherlands.
authors.forename: Essam M
authors.initials: EM
authors.lastname: Dief
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany. Electronic address: christian.haering@embl.de.
authors.forename: Christian H
authors.initials: CH
authors.lastname: Haering
authors.affiliation: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft 2628 CJ, the Netherlands. Electronic address: c.dekker@tudelft.nl.
authors.forename: Cees
authors.initials: C
authors.lastname: Dekker
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015825:Chromosomes, Fungal / Q000737:chemistry* / Q000648:ultrastructure; D015870:Gene Expression; D007091:Image Processing, Computer-Assisted; D018625:Microscopy, Atomic Force / Q000379:methods; D056004:Molecular Dynamics Simulation; D057054:Molecular Imaging; D009010:Monte Carlo Method; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000072417:Protein Domains; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; C090455:SMC2 protein, S cerevisiae; C409162:SMC4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins