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Active loop extrusion - the process of formation of dynamically growing chromatin loops due to the motor activity of DNA-binding protein complexes - is firmly established mechanism responsible for chromatin spatial organization at different…

Statistical Mechanics · Physics 2023-01-11 Sergey Belan , Vladimir Parfenyev

We consider a model of a Rouse polymer extended by the mechanism of active loop extrusion. The model is based on a kinetic equation that is valid provided that the extrusion rate is high enough and the resulting loop ensemble is…

Statistical Mechanics · Physics 2025-05-09 Ilya Nikitin , Nikolay Masnev , Sergey Belan

We investigate the kinetics of loop formation in flexible ideal polymer chains (Rouse model), and polymers in good and poor solvents. We show for the Rouse model, using a modification of the theory of Szabo, Schulten, and Schulten, that the…

Soft Condensed Matter · Physics 2007-11-13 Ngo Minh Toan , Greg Morrison , Changbong Hyeon , D. Thirumalai

We extend the Rouse model of polymer dynamics to situations of non-stationary chain growth. For a dragged polymer chain of length $N(t) = t^\alpha$, we find two transitions in conformational dynamics. At $\alpha= 1/2$, the propagation of…

Soft Condensed Matter · Physics 2016-07-25 Ali Malek , Reiner Kree

We investigate the conformational and dynamical properties of a partially active Rouse chain, where activity is localized within a specific segment, positioned at various locations along the chain and spanning any given length. Through…

Soft Condensed Matter · Physics 2024-12-06 Koushik Goswami , Norman Hsia , Cheng-Hung Chang , Hong-Yan Shih

An active loop-extrusion mechanism is regarded as the main out--of--equilibrium mechanism responsible for the structuring of megabase-sized domains in chromosomes. We developed a model to study the dynamics of the chromosome fibre by…

Biomolecules · Quantitative Biology 2020-09-30 M. Crippa , Y. Zhan , G. Tiana

We discuss simulations of a simple model for polymer blends in the framework of the Rouse model. At odds with standard predictions, large dynamic asymmetry between the two components induces strong non-exponentiality of the Rouse modes for…

Soft Condensed Matter · Physics 2009-11-13 Angel J. Moreno , Juan Colmenero

We develop a kinetic theory of cohesin-driven loop extrusion on a disordered chromatin track with transient barriers. In the stationary state, the mean loop size is shown to obey a universal law determined by the bare processivity and a…

Soft Condensed Matter · Physics 2026-04-20 A. Chervinskaya , R. Metzler , K. E. Polovnikov

We present a semi-analytical approach to the determination of the dynamic properties of randomly branched polymers under the Rouse approximation. The principle procedure is based on examining a spectrum of eigenvalues which represents the…

Statistical Mechanics · Physics 2009-10-31 Josh P. Kemp , Zheng Yu Chen

Chromosomes are crumpled polymer chains further folded into a sequence of stochastic loops via loop extrusion. While extrusion has been verified experimentally, the particular means by which the extruding complexes bind DNA polymer remains…

Soft Condensed Matter · Physics 2023-06-14 Kirill Polovnikov , Bogdan Slavov

Chromatin loop extrusion is a popular model for the formation of CTCF loops and topological domains. Recent HiC data have revealed a strong bias in favour of a particular arrangement of the CTCF binding motifs that stabilize loops, and…

Biological Physics · Physics 2020-10-07 C. A. Brackley , J. Johnson , D. Michieletto , A. N. Morozov , M. Nicodemi , P. R. Cook , D. Marenduzzo

Condensation of hundreds of mega-base-pair-long human chromosomes in a small nuclear volume is a spectacular phenomenon. This process is driven by the formation of chromosome loops. ATP consuming motor, condensin, interacts with chromatin…

Soft Condensed Matter · Physics 2021-10-27 Ryota Takaki , Atreya Dey , Guang Shi , Dave Thirumalai

Loop extrusion convincingly describes how certain Structural Maintenance of Chromosome (SMC) proteins mediate the formation of large DNA loops. Yet, most of the existing computational models cannot reconcile recent in vitro observations…

Soft Condensed Matter · Physics 2022-01-12 Andrea Bonato , Davide Michieletto

We present large-scale molecular dynamics simulations for a coarse-grained model of polymer melts in equilibrium. From detailed Rouse mode analysis we show that the time-dependent relaxation of the autocorrelation function (ACF) of modes…

Soft Condensed Matter · Physics 2017-04-26 Hsiao-Ping Hsu , Kurt Kremer

If a semiflexible polymer confined to a narrow channel bends around by 180 degrees, the polymer is said to exhibit a hairpin. The equilibrium extension statistics of the confined polymer are well understood when hairpins are vanishingly…

Loop extrusion by motor proteins mediates the attractive interactions in chromatin on the length scale of megabases, providing the polymer with a well-defined structure and at the same time determining its dynamics. The mean square…

Biomolecules · Quantitative Biology 2023-07-12 E. Marchi , Y. Zhan , G. Tiana

We investigate extensional viscosity and polymer conformation in dilute polymer solutions under uniaxial extensional flow using dissipative particle dynamics simulations. At high extension rates, polymers are significantly stretched by…

Soft Condensed Matter · Physics 2025-11-27 Yusuke Koide , Takato Ishida , Takashi Uneyama , Yuichi Masubuchi

By means of computer simulations, we investigate the relaxation of the Rouse modes in a simple bead-spring model for non-entangled polymer blends. Two different models are used for the fast component, namely fully-flexible and semiflexible…

Soft Condensed Matter · Physics 2015-05-20 Marco Bernabei , Angel J. Moreno , Juan Colmenero

Assuming Gaussian chain statistics along the chain contour, we generate by means of a proper fractal generator hyperbranched polymer trees which are marginally compact. Static and dynamical properties, such as the radial intrachain pair…

Soft Condensed Matter · Physics 2022-02-01 M. Dolgushev , J. P. Wittmer , A. Johner , O. Benzerara , H. Meyer , J. Baschnagel

We present a model for semiflexible polymers in Hamiltonian formulation which interpolates between a Rouse chain and worm-like chain. Both models are realized as limits for the parameters. The model parameters can also be chosen to match…

Soft Condensed Matter · Physics 2015-06-12 Gerard T. Barkema , J. M. J. van Leeuwen
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