Frequent gene fissions associated with human pathogenic bacteria

- We examine 104 human bacterial pathogens for gene fusions and fissions.
- 23% of gene fusions/fissions have occurred multiple times throughout evolution.
- Most of the events identified were recent events specific to pathogenic bacteria.
- In our dataset gene fissions are seven times more common than fusions.
- This indicates positive selection for small proteins in human pathogenic bacteria.

Gene fusion and fission events are important for evolutionary studies and for predicting protein-protein interactions. Previous studies have shown that fusion events always predominate over fission events and, in their majority, they represent singular events throughout evolution. In this project, the role of fusion and fission events in the genome evolution of 104 human bacterial pathogens was studied. 141 protein pairs were identified to be involved in gene fusion or fission events. Surprisingly, we find that, in the species analyzed, gene fissions prevail over fusions. Moreover, while most events appear to have occurred only once in evolution, 23% of the gene fusion and fission events identified are deduced to have occurred independently multiple times. Comparison of the analyzed bacteria with non-pathogenic close relatives indicates that this impressive result is associated with the recent evolutionary history of the human bacterial pathogens, and thus is probably caused by their pathogenic lifestyle.