What does mining ICE in bacterial genomes reveal?

Abstract

Conjugative elements play a major role in bacterial evolution. They have been widely studied when associated with plasmids, however, the role and importance of Integrative and Conjugative Elements (ICE) remain less clear. Yet, it has been shown that ICEs are more abundant than conjugative plasmids in bacterial genomes. Using comparative genomics, we analyzed about 200 ICEs, which we delimited precisely. This unique dataset allowed us to have a more general picture of ICEs. We could outline for the first time their general organization and their relation to their host’s genome. More importantly, we infer some evolutionary properties of ICEs. Indeed we look for a wide range of mobile genetic element associated functions like restriction modification systems, integrons, toxin-antitoxins, entry-exclusion systems, among other functions. This accurate annotation allowed us to better understand ICE’s relationship to its host. This provides quantitative new information on ICEs and allows us to better understand their broader role in the evolution of bacteria.