Finite-Size Conformational Transitions: A Unifying Concept Underlying Chromosome Dynamics

作     者：Bertrand R.Caré Pascal Carrivain Thierry Forné Jean-Marc Victor Annick Lesne 

作者机构：Laboratoire de Physique Théorique de la Matière CondenséeCNRS UMR 7600UPMC University Paris 06F-75005ParisFrance CNRS GDR 3536UPMC University Paris 06F-75005ParisFrance Institut de Génétique HumaineCNRS UPR 1142 MontpellierFrance Institut de Génétique Moléculaire de MontpellierCNRS UMR 5535University of MontpellierMontpellierFrance Kavli Institute for Theoretical Physics ChinaCAS 

出 版 物：《Communications in Theoretical Physics》 (理论物理通讯（英文版）)

年 卷 期：2014年第61卷第10期

页      面：607-616页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 09[农学] 071007[理学-遗传学] 0901[农学-作物学] 0704[理学-天文学] 090102[农学-作物遗传育种] 0702[理学-物理学] 

基　　金：the program "Small Systems Nonequilibrium Fluctuations,Dynamics and Stochastics,and Anomalous Behavior" of the Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences(KITPC),held in Bejing in July 2013 funded by the French Institut de la Recherche M'edicale,under Grant MICROMEGAS PC201104 the French Institut National du Cancer,under Grant INCa-5960 the French Agence Nationale de la Recherche under Grant No.ANR-13-BSV5-0010-03.UPMC belongs to Sorbonne Universit'es 

主　　题：coil-globule transition helix-coil transition chromosome conformational capture two-state model 

摘      要：Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.