Genomic inversions in Escherichia coli alter gene expression and are associated with nucleoid protein binding sites.

Genomic reorganization, such as rearrangements and inversions, influences how genetic information is organized within the bacterial genomes. Inversions, in particular, facilitate genome evolution through gene gain and loss, and can alter gene expression. Previous studies have investigated the impact inversions have on gene expression induced inversions targeting specific genes or examine inversions between distantly related species. This fails to encompass a genome-wide perspective of naturally occurring inversions and their post-adaptation impact on gene expression. Here, we used bioinformatic techniques and multiple RNA-seq datasets to investigate the short- and long-range impact inversions have on genomic gene expression within Escherichia coli. We observed differences in gene expression between homologous inverted and non-inverted genes even after long-term exposure to adaptive selection. In 4% of inversions representing 33 genes, differential gene expression between inverted and non-inverted homologs was detected, with greater than two-thirds (71%) of differentially expressed inverted genes having 9.4-85.6-fold higher gene expression. The identified inversions had more overlap than expected with nucleoid-associated protein binding sites, which assist in the regulation of genomic gene expression. Some inversions can drastically impact gene expression, even between different strains of E. coli, and could provide a mechanism for the diversification of genetic content through controlled expression changes.