Cross-linker mediated compaction and local morphologies in a model chromosome. (12th June 2019)

• Record Type: Journal Article
• Authors: Kumar, Amit; Chaudhuri, Debasish
• Is Part Of: Journal of physics. Volume 31:Number 35(2019)
• Publication Date: 2019-06-12
• Subjects: chromosome organization -- coil-globule transition -- loop topology -- chromatin and cross-linkers -- zippering; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ab2350
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Chromatin and associated proteins constitute the highly folded structure of chromosomes. We consider a self-avoiding polymer model of the chromatin, segments of which may get cross-linked via protein binders that repel each other. The binders cluster together via the polymer mediated attraction, in turn, folding the polymer. Using molecular dynamics simulations, and a mean field description, we explicitly demonstrate the continuous nature of the folding transition, characterized by unimodal distributions of the polymer size across the transition. At the transition point the chromatin size and cross-linker clusters display large fluctuations, and a maximum in their negative cross-correlation, apart from a critical slowing down. Along the transition, we distinguish the local chain morphologies in terms of topological loops, inter-loop gaps, and zippering. The topologies are dominated by simply connected loops at the criticality, and by zippering in the folded phase.