We study theoretically the replication of Kinetoplast DNA consisting of several thousands separate mini-circles found in organisms of the class Kinetoplastida. When the cell is not actively dividing these are topologically connected in a marginally linked network of rings with only one connected component. During cell division each mini-circle is removed from the network, duplicated and then re-attached, along with its progeny. We study this process under the hypothesis that there is a coupling between the topological state of the mini-circles and the expression of genetic information encoded on them, leading to the production of Topoisomerase. This model describes a self-regulating system capable of full replication that reproduces several previous experimental findings. We find that the fixed point of the system depends on a primary free parameter of the model: the ratio between the rate of removal of mini-circles from the network (R) and their (re)attachment rate (A). The final topological state is found to be that of a marginally linked network structure in which the fraction of mini-circles linked to the largest connected component approaches unity as R/A decreases. Finally we discuss how this may suggest an evolutionary trade-off between the speed of replication and the accuracy with which a fully topologically linked state is produced.
Nucleoid clustering drives stepwise expansion and segregation of replicating bacterial chromosomes
SUPA, School of Physics and Astronomy, University of Edinburgh（爱丁堡大学物理与天文学学院）；Dipartimento di Fisica e Astronomia and Sezione INFN, Universitá di Padova（帕多瓦大学物理与天文学系及INFN分部）
ParABS system induces topological modifications to spatio-temporally organize its mother and daughter chromosomes in the replicating C. crescentus cell
Indian Institute of Science Education and Research (IISER-Pune)（印度科学教育研究所（浦那））
