Catch-bond behavior of DNA condensate under tension  

作　　者：李伟 Wong Wei-Juan Lim Ci-Ji 车海鹏 李明 严洁 王鹏业 

机构地区：[1]Beijing National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics,Institute of Physics, Chinese Academy of Sciences [2]Department of Physics, National University of Singapore, Singapore 117542,and Mechanobiology Institute, National University of Singapore

出　　处：《Chinese Physics B》2015年第12期105-108,共4页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.11104341;11474346;11274374;and 61275192);the National Key Basic Research Program of China(Grant No.2013CB837200);the Mechanobiology Institute at National University of Singapore

摘　　要：Toroid formation is an important mechanism underlying DNA condensation, which has been investigated extensively by single-molecule experiments in vitro. Here, the de-condensation dynamics of DNA condensates were studied using magnetic tweezers combined with Brownian dynamics simulations. The experimental results revealed a surprising nonmonotonic dependence of the unfolding rate on the force applied under strong adhesion conditions, resembling the catchbond behavior reported in the field of ligand-receptor interactions. Simulation results showed that the different unfolding pathways of DNA condensate under large forces derive from the force-dependent deformation of the DNA toroid, which explains the catch-bond behavior of DNA condensate in the magnetic tweezers experiments. These results challenge the universality of the regular toroidal DNA unwrapping mechanism and provide the most complete description to date of multivalent cation-dependent DNA unwrapping under tension.Toroid formation is an important mechanism underlying DNA condensation, which has been investigated extensively by single-molecule experiments in vitro. Here, the de-condensation dynamics of DNA condensates were studied using magnetic tweezers combined with Brownian dynamics simulations. The experimental results revealed a surprising nonmonotonic dependence of the unfolding rate on the force applied under strong adhesion conditions, resembling the catchbond behavior reported in the field of ligand-receptor interactions. Simulation results showed that the different unfolding pathways of DNA condensate under large forces derive from the force-dependent deformation of the DNA toroid, which explains the catch-bond behavior of DNA condensate in the magnetic tweezers experiments. These results challenge the universality of the regular toroidal DNA unwrapping mechanism and provide the most complete description to date of multivalent cation-dependent DNA unwrapping under tension.

关 键 词：DNA toroid magnetic tweezers catch bond 

分 类 号：Q523[生物学—生物化学]