Diversity, Origin and Evolution of the ESCRT Systems

<title>Abstract</title> ESCRT (Endosomal Sorting Complexes Required for Transport) is a multicomponent system that plays a key role in protein sorting between membrane-bounded compartments of eukaryotic cells. Homologs of many ESCRT components are identifiable in various groups of archaea but not in bacteria. We performed a comprehensive search for ESCRT protein homologs in archaea and attempted to reconstruct ESCRT evolution using as a scaffold the phylogenetic tree of Vps4 ATPase (ESCRT IV). This reconstruction suggests that the Last Archaeal Common Ancestor possessed a complex ESCRT system that was involved in protein sorting. Subsequent evolution involved either simplification, as in the TACK superphylum, where ESCRT was co-opted for cell division, or complexification as in Asgardarchaeota, the archaeal ancestors of eukaryotes. In Asgard archaea, distinct ESCRT components evolved by gene or domain duplication and recruitment of additional domains, and connection between ESCRT and the ubiquitin system previously considered a eukaryotic signature was established.