Genome diversification via genetic exchanges between temperate and virulent bacteriophages
Résumé
Bacteriophages (henceforth phages) evolve by mutation and recombination. Temperate phages are known to evolve rapidly by genetic exchanges. In contrast, recombination events between virulent and between temperate and virulent phages have rarely been reported. A gene flow barrier between these two large distinct groups of phages could affect the ability of phages to acquire novel functions. Here, we show that genomes of temperate and virulent phages are very distinct but often have a few almost identical genes. These cases are due to recent genetic exchanges of both phage-like and bacterial-like genes. These exchanges were probably mediated by phage recombinases with low homology requirements and mechanisms of non-homologous end joining, since both were over-represented in recombinant phages and their hosts. When assessing the impact of gene flow across the two populations of phages we realized that temperate phages have narrower host ranges than virulent phages. This suggests, and we find some evidence, that gene flow between temperate phages infecting distant bacterial hosts might be mediated by recombination with the broader host virulent phages. Hence, gene flow across phages with distinct lifestyles could drastically increase the gene repertoire available for phage evolution, including the transfer of functional innovations across taxa. These results also have implications for bacterial evolution because of the impact of phage predation in bacterial population dynamics and the contribution of temperate phages to the evolution of bacterial gene repertoires.
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers produits par l'(les) auteur(s)
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