Colocalization of distant chromosomal loci in space in E. coli: a bacterial nucleolus.

The spatial organization of DNA within the bacterial nucleoid remains unclear. To investigate chromosome organization in Escherichia coli, we examined the relative positions of the ribosomal RNA (rRNA) operons in space. The seven rRNA operons are nearly identical and separated from each other by as much as 180° on the circular genetic map, a distance of ≥2 million base pairs.