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Replisomes restrict SMC-mediated DNA-loop extrusion in vivo
Biorxiv : the Preprint Server for Biology
|March 3, 2025
Summary
The DNA replisome acts as a barrier to structural maintenance of chromosomes (SMC) complexes, restricting their movement during DNA loop extrusion in vivo. This interaction impacts genome organization and essential cellular processes.
Area of Science:
- Molecular Biology
- Genomics
- Cell Biology
Background:
- Structural maintenance of chromosomes (SMC) complexes are crucial for genome organization via DNA loop extrusion.
- DNA replication machinery (replisomes) duplicate chromosomes, frequently colliding with SMC complexes.
- The in vivo resolution of these collisions is poorly understood.
Purpose of the Study:
- To investigate the in vivo interaction between SMC complexes and the replisome.
- To determine how collisions between these molecular machines are resolved.
- To understand the impact of replisomes on SMC complex translocation.
Main Methods:
- Engineered head-on and head-to-tail collisions between SMC complexes and replisomes in Bacillus subtilis.
- Monitored replisome progression using marker frequency analysis.
- Tracked SMC translocation via time-resolved ChIP-seq and Hi-C, complemented by simulations.
Main Results:
- SMC complexes did not impede replisome progression.
- Replisomes restricted SMC translocation irrespective of collision orientation.
- SMC complexes were observed to be blocked, released, or occasionally bypass the replisome.
Conclusions:
- The replisome acts as a barrier to SMC-mediated DNA-loop extrusion in vivo.
- This finding has significant implications for chromosome segregation, DNA repair, and gene regulation.
- Understanding this interaction is vital for comprehending dynamic chromosome organization across all organisms.
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