Transcription is one of the most fundamental processes for life. In eukaryotic cells, transcriptional activity is regulated to a large degree by chromosome packaging.
In bacteria, despite the absence of a nuclear envelope and many of the DNA-packaging proteins of eukaryotes, the chromosome is still highly condensed into a structured object, the nucleoid. The spatial organization of transcription within the nucleoid and the effect of transcription on DNA organization remain poorly understood. In this work, we characterize how RNA polymerase accesses transcription sites on DNA, and show that active transcription can cause spatial reorganization of the nucleoid, with movement of gene loci out of the bulk of DNA as levels of transcription increase.