Spatial Organization of Biological Fuctions | BPS Thematic Meeting

Spatial Organization of Biological Functions Meeting

Tuesday Speaker Abstracts

ENTROPIC ORGANIZATION AND DEMIXING OF TOMO POLYMERS AS MODELS OF CHROMOSOMES Kingkini Roychoudhury 1 ; Shreerang Pande 1 ; Shailesh Sathe 1 ; Debarshi Mitra 1 ; Apratim Chatterji 1 ; 1 IISER Pune, Physics, Pune, India Segregation of polymers under cylindrical confinement to maximize conformational entropy has previously been identified as the primary mechanism of chromosome segregation in E. coli [1,2]. Therefore, we aim to investigate how entropy can aid in daughter chromosome segregation and organization in bacterial cells with spherical geometries, like Staphylococcus aureus. As pure ring polymers will remain mixed under spherical confinement, we create Topologically Modified(ToMo) polymers, where we introduce cross-links between specific monomers on the ring polymer contour to create a cluster of internal loops connected to a bigger loop(similar to the action of loop extruding proteins in a chromosome). We have previously explored different aspects of ToMo polymers to effectively tune entropic interactions and drive organization within the sphere. Consequently, we have observed an emergent radial organization of the polymer segments in the sphere [3]. We further extend our previous work by improving the design of ToMo polymers and investigating two such polymers in a sphere. We analyze their organization and demixing, and relevance to daughter chromosome organization in spherical bacteria. We also demonstrate that multiple ToMo polymers remain more demixed in a sphere than pure ring or linear polymers. In our simulations, we have used the bead-spring model of polymers, where there are only repulsive excluded volume interactions between the monomers, ensuring that the observed organization is purely entropy-driven. 1. D. Mitra, S. Pande, and A. Chatterji. Soft Matter, 18:5615–5631, 2022.2. D. Mitra, S. Pande, and A. Chatterji. Phys. Rev. E, 106:054502, Nov 2022.3. Kingkini Roychoudhury, S. Pande, I. S. Shashank, D. Mitra, and A. Chatterji. arXiv:2501.02276 [Being refereed for publication in Phys. Rev. E]

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