Single-Molecule Imaging Reveals a Collapsed Conformational State for DNA-Bound Cohesin.
Cohesin is essential for the hierarchical organization of the eukaryotic genome and plays key roles in many aspects of chromosome biology. The conformation of cohesin bound to DNA remains poorly defined, leaving crucial gaps in our understanding of how cohesin fulfills its biological functions. Here, we use single-molecule microscopy to directly observe the dynamic and functional characteristics of cohesin bound to DNA. We show that cohesin can undergo rapid one-dimensional (1D) diffusion along DNA, but individual nucleosomes, nucleosome arrays, and other protein obstacles significantly restrict its mobility. Furthermore, we demonstrate that DNA motor proteins can readily push cohesin along DNA, but they cannot pass through the interior of the cohesin ring. Together, our results reveal that DNA-bound cohesin has a central pore that is substantially smaller than anticipated. These findings have direct implications for understanding how cohesin and other SMC proteins interact with and distribute along chromatin.
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
Johannes
J
Stigler
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Gamze Ö
GÖ
Çamdere
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. Electronic address: koshland@berkeley.edu.
Douglas E
DE
Koshland
Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA. Electronic address: ecg2108@cumc.columbia.edu.
Eric C
EC
Greene
D020856:AT Rich Sequence / Q000235:genetics; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004058:Diffusion; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism; D016062:Porosity; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism*; D000072760:Single Molecule Imaging / Q000379:methods*; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004247:DNA; D020409:Molecular Motor Proteins; D009707:Nucleosomes; D029702:Schizosaccharomyces pombe Proteins; D000097722:Cohesins