Plasmids and temperate phages are key contributors to bacterial evolution. They’re often considered very distinct. Nonetheless, some parts, termed phage-plasmids, are identified to be each plasmids and phages, e.g. P1, N15 or SSU5. The quantity, distribution, relatedness and traits of those phage-plasmids are poorly identified.
Right here, we screened for these parts amongst ca. 2500 phages and 12000 plasmids and recognized 780 phage-plasmids throughout very various bacterial phyla. We grouped 92% of them by similarity of gene repertoires to eight outlined teams and 18 different broader communities of parts.
The existence of those giant teams means that phage-plasmids are historic. Their gene repertoires are giant, the typical ingredient is bigger than a mean phage or plasmid, and so they embrace barely extra homologs to phages than to plasmids.
We analyzed the pangenomes and the genetic group of every group of phage-plasmids and located the important thing phage genes to be conserved and co-localized inside distinct teams, whereas genes with homologs in plasmids are way more variable and embrace most accent genes.
Phage-plasmids are a sizeable fraction of the sequenced plasmids (∼7%) and phages (∼5%), and will have key roles in bridging the genetic divide between phages and different cell genetic parts.