Confined ring polymers as a model nucleoid

The bacterial chromosome is tightly packed in an intracellular space called the nucleoid with its loci linearly and precisely positioned. Here we propose a model nucleoid: a ring polymer confined in a cylindrical space. When the cylinder-ring parameters are chosen properly, our model describes the observed locus distributions of the {\it E. coli} chromosome surprisingly well. Our results illustrate how the geometry and function of the nucleoid are interrelated.