Do Inteins Serve as Mediators of Epigenetic Inheritance in Prokaryotes?

Intervening proteins, or inteins, are mobile genetic elements that are abundant in bacteria and archaea. Inteins are translated within host proteins and removed through a self-mediated protein splicing reaction. Due to their mobility between genomes, these elements have long been assumed to be nothing more than parasitic sequences that burden the host. In contrast to this perspective, compelling reports over the last decade have challenged the assumption that inteins are purely selfish, demonstrating several examples of conditional protein splicing (CPS). In CPS, the rate and accuracy of the protein splicing reaction, and in turn the dosage of functional host protein, varies greatly depending on environmental conditions. As inteins generally cluster to conserved proteins involved in critical processes such as DNA replication, CPS may represent a widespread mechanism of post-translational regulation in prokaryotes. Here, we propose that inteins may function as mediators of epigenetic inheritance in prokaryotes by modulating the levels of active host proteins in response to environmental cues, ultimately communicating information to daughter cells about recent stress.