Fig. 2.

Summary of the functional roles of domesticated retroelements in prokaryotes. The functional significance of DGR hypermutation is depicted in phage that diversify tail tip proteins in order to attach to variable host receptors. Additional cellular DGR targets in Legionella pneumophila and Treponema denticola encode outer membrane proteins whose specific functions remain unknown. Retrons in E. coli have been shown to activate effector proteins that trigger abortive infection and cell arrest. In the case of other bacterial retrons, msDNA may directly inhibit effector proteins, serving as a toxin/antitoxin system. Figure created with BioRender.com