Organization and segregation of bacterial chromosomes and plasmids revealed by the dynamics of DNA loci

Yi-Ren Chang^1*

¹Department of Physics, National Taiwan Normal University, Taipei, Taiwan

* Presenter:Yi-Ren Chang, email:yrchang@ntnu.edu.tw

The thermal-driven motions of DNA segments and the expression of the encoded genes play important roles in the organization and segregation of the gene materials in bacterial cells. To discover the underlying mechanism, the motions of single gene loci on the bacterial chromosome and plasmids were fluorescently tagged and tracked. Hence, the repositioning, transfer, and diffusion of the gene loci and the respective DNA segments in cellular space were revealed, consequently. It is found that in the confined and viscoelastic cellular environment, the DNA segments can be relocated, relaxed, or bent to satisfy the spatial need for efficient gene expression of the encoded gene operons. The altered local organizations also reflect the types of expressed proteins, and it refers to the possible linkage between the DNA segment to the cell membrane. Besides, the motion of high-copy-number plasmids is not only limited by the confinement of the cell boundary and the repulsion from the nucleoid but also dragged due to the interaction induced by gene expressions. It, therefore, leads to the heterogeneous partition and increases the diversity between cells.

Keywords: Single molecule tracking, in-vivo DNA dynamics, DNA organization