Prevalence and Evolutionary Implications of Genome Rearrangements in Bacteria.

The genetic material of bacteria and archaea is organized into various structures and setups, attesting that genome architecture is dynamic in these organisms. However, strong selective pressures are also acting to preserve genome organization, and it remains unclear how frequently genomes experience rearrangements and what mechanisms lead to these processes. Here, we assessed the dynamics and the drivers of genomic rearrangements across 121 microbial species. We show that synteny is highly conserved within most species, although several species present exceptionally flexible genomic layouts. Our results show that genomic rearrangements occur at a variable pace across bacteria and archaea, pointing to different selective constraints driving the accumulation of genomic changes across species. Importantly, we found that not only inversions but also translocations are highly enriched near the origin of replication (Ori), which suggests that many rearrangements may confer an adaptive advantage to the cell through the relocation of genes that benefit from gene dosage effects. Finally, our results confirm the view that mobile genetic elements-in particular transposable elements-are the main drivers of genomic translocations and inversions. Overall, our study shows that microbial species present largely stable genomic layouts and identifies key patterns and drivers of genome rearrangements in prokaryotes.