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Biological Sciences - Article
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Condensin plays a central role in the organisation of chromosomes by compacting chromatin into loops during mitosis. Condensin achieves this through a loop extrusion mechanism that remains poorly understood. To identify the molecular steps of yeast condensin during loop formation, we used optical tweezers with fluorescence detection. We find that single yeast condensin complexes use ATP to extrude DNA through distinct 15 nm steps, thus advancing ~45 base pairs (bp) per step. Under increasing load, the condensin step size remains constant while step-dwell times increase, and stalls at forces >1 pN. We also show that nucleosome arrays hinder processive condensin extrusion and demonstrate that the histone chaperone FACT is required for compaction of nucleosomal arrays by condensin. Importantly, FACT-assisted compaction on nucleosomes also occurs through distinct 15 nm steps. Finally, we show that FACT is required for correct condensin localisation in vivo. Our results establish that loop extrusion by yeast condensin involves a 45 bp stroke that requires FACT for condensin function on chromatin.
Keywords
yeast condensin, loop formation, loop extrusion
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There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
- SupplVideo1.mp4
Supplementary Video 1
- SupplVideo2.mp4
Supplementary Video 2
- SupplVideo3.mp4
Supplementary Video 3
- SupplVideo4.mp4
Supplementary Video 4
- SupplVideo5.mp4
Supplementary Video 5
- SupportinginformationFinal.docx
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This preprint is under consideration at a Nature Portfolio Journal. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Nature journals have partnered with Research Square to offer In Review, a journal-integrated preprint deposition service.
Biological Sciences - Article
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 1
Posted 05 Oct, 2021
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Condensin plays a central role in the organisation of chromosomes by compacting chromatin into loops during mitosis. Condensin achieves this through a loop extrusion mechanism that remains poorly understood. To identify the molecular steps of yeast condensin during loop formation, we used optical tweezers with fluorescence detection. We find that single yeast condensin complexes use ATP to extrude DNA through distinct 15 nm steps, thus advancing ~45 base pairs (bp) per step. Under increasing load, the condensin step size remains constant while step-dwell times increase, and stalls at forces >1 pN. We also show that nucleosome arrays hinder processive condensin extrusion and demonstrate that the histone chaperone FACT is required for compaction of nucleosomal arrays by condensin. Importantly, FACT-assisted compaction on nucleosomes also occurs through distinct 15 nm steps. Finally, we show that FACT is required for correct condensin localisation in vivo. Our results establish that loop extrusion by yeast condensin involves a 45 bp stroke that requires FACT for condensin function on chromatin.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
There is NO Competing Interest.
This is a list of supplementary files associated with this preprint. Click to download.
- SupplVideo1.mp4
Supplementary Video 1
- SupplVideo2.mp4
Supplementary Video 2
- SupplVideo3.mp4
Supplementary Video 3
- SupplVideo4.mp4
Supplementary Video 4
- SupplVideo5.mp4
Supplementary Video 5
- SupportinginformationFinal.docx
Supplementary Information
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