In/Out Swappable Polymer Brush Model of DNA Kinetoplast

Kinetoplasts are complexes made up of cyclic DNA typically observed to form curved spherical caps in mitochondria. We model this topologically entangled ring network as an underlying entangled ring-membrane with extraneous rings that can arrange themselves to protrude on either side of the membrane. We model these rings as polymers grafted to a semi-rigid substrate in a strong-stretching limit for various solvent concentrations. Each grafted polymer is free to arrange itself to extend from either side of the membrane (a toy model for the actual knotted topology of each DNA ring). We show that this model predicts a spontaneous curvature driven by chain entropy and stabilized by the underlying stiffness of the ring-mat. Apart from modelling this biological system, this “swappable-graft” polymer system could result in interesting textures in engineered 2D polymers.