| Abstrakt: |
Escherichia coli exhibit extensive genetic diversity at the genome level, particularly within their accessory genome. The tRNA integrated genomic islands (GIs), a part of the E. coli accessory genome, play an important role in pathogenicity. However, studies examining the evolution of GIs have been challenging due to their large size, considerable gene content variation and fragmented assembly in draft genomes. Here we examined the evolution of the GI integrated at pheV-tRNA (GI-pheV), with a primary focus on uropathogenic E. coli (UPEC) and the globally disseminated multidrug resistant ST131 clone. We show the gene content of GI-pheV is highly diverse and arranged in a modular configuration, with the P4 integrase encoding gene intP4 the only conserved gene. Despite this diversity, the GI-pheV gene content displayed conserved features among strains from the same pathotype. In ST131, GI-pheV corresponding to the reference strain EC958 (EC958_GI-pheV) was found in ~90% of strains. Phylogenetic analyses suggested that GI-pheV in ST131 has evolved together with the core genome, with the loss/gain of specific modules (or the entire GI) linked to strain specific events. Overall, we show GI-pheV exhibits a dynamic evolutionary pathway, in which modules and genes have evolved through multiple events including insertions, deletions and recombination. Author summary: Genomic islands (GIs) are key contributors to E. coli pathogenesis. However, studies on the evolution of GIs are limited, mostly due to their large size, variation, and fragmented assembly in draft genomes. Here we investigated the evolution of the GI-pheV genomic island. We showed that the presence of GI-pheV is primarily associated with pathogenic E. coli, with the greatest diversity in gene content observed among strains from different pathotypes. The GI-pheV in UPEC contains uropathogenicity-associated virulence and fitness encoding modules, which have either co-evolved with the island or evolved independently, possibly due to different selective pressures. Focused investigation of GI-pheV in ST131, the most globally dominant antibiotic resistant UPEC clone, revealed loss or gain of genes and modules via recombination during its evolution. [ABSTRACT FROM AUTHOR] |
