Loop extrusion driven volume phase transition of entangled chromosomes

Research output: Contribution to journalResearch articleContributedpeer-review



Experiments on reconstituted chromosomes have revealed that mitotic chromosomes are assembled even without nucleosomes. When topoisomerase II (topo II) is depleted from such reconstituted chromosomes, these chromosomes are not disentangled and form “sparklers,” where DNA and linker histone are condensed in the core and condensin is localized at the periphery. To understand the mechanism of the assembly of sparklers, we here take into account the loop extrusion by condensin in an extension of the theory of entangled polymer gels. The loop extrusion stiffens an entangled DNA network because DNA segments in the elastically effective chains are translocated to loops, which are elastically ineffective. Our theory predicts that the loop extrusion by condensin drives the volume phase transition that collapses a swollen entangled DNA gel because the stiffening of the network destabilizes the swollen phase. This may be an important piece to understand the mechanism of the assembly of mitotic chromosomes.


Original languageEnglish
Pages (from-to)2742-2750
Number of pages9
JournalBiophysical Journal
Issue number14
Publication statusPublished - 14 Jun 2022

External IDs

Scopus 85132907326
PubMed 35706364
WOS 000837982600008
Mendeley 7345b12b-9ddb-3144-9bb7-504fce36fe08


ASJC Scopus subject areas


  • Chromatin, Chromosomes/metabolism, DNA/genetics, DNA Topoisomerases, Type II/genetics, Histones/genetics, Mitosis, Nucleosomes, Organization, Elasticity, Roles, Condensation, Dynamics, Dna, Bacteria

Library keywords