Missing Pieces of an Ancient Puzzle: Evolution of the Eukaryotic Membrane-Trafficking System

Abstract

The membrane-trafficking system underpins cellular trafficking of material in eukaryotes and its evolution would have been a watershed in eukaryogenesis. Evolutionary cell biological studies have been unraveling the history of proteins responsible for vesicle transport and organelle identity revealing both highly conserved components and lineage-specific innovations. Recently, endomembrane components with a broad, but patchy, distribution have been observed as well, pieces that are missing from our cell biological and evolutionary models of membrane trafficking. These data together allow for new insights into the history and forces that shape the evolution of this critical cell biological system.

Vacuolar protein sorting mechanisms in apicomplexan parasites

“…In fact, most of the trafficking factors (i.e. Rab-GTPases, SNARES and tethers) were present in the last common eukaryotic ancestor and subsequent gene duplications or secondary loss led to complex and specialised endomembrane systems in diverse eukaryotes [3], [4].…”

The changing view of eukaryogenesis – fossils, cells, lineages and how they all come together

“…It has been proposed that an iterative model of paralogue expansion and co-evolution of these interacting paralogues producing exclusive organelle and pathway-specific versions can explain the generation of new cellular compartments (Dacks and Field, 2007;Dacks et al, 2008). Again, comparative genomic and phylogenetic studies demonstrate that expansion of these families in the LECA had reached a level of sophistication that rivals that seen in many modern eukaryotes (Koumandou et al, 2013;Schlacht et al, 2014). The order of this expansion, however, represents another set of transitional events from FECA to LECA that remain to be resolved.…”

The Future of Cell Biology: Emerging Model Organisms

“…For example, membrane trafficking is solely a phenomenon of eukaryotic biology; investigating its origins provides a valuable complementary approach for identifying key regulatory mechanisms (Schlact et al, 2014; Richardson et al, 2015). The traditional model organisms are all members of a recently derived group sometimes referred to as the “crown eukaryotes” and provide only a narrow window into the evolution of membrane trafficking.…”

“…The traditional model organisms are all members of a recently derived group sometimes referred to as the “crown eukaryotes” and provide only a narrow window into the evolution of membrane trafficking. By studying diverse but less well known single-celled eukaryotes such as the excavate Naegleria gruberi, the rhizarian Bigelowiella natans , and the cryptophyte Guillardia theta, it has become clear which membrane trafficking proteins are ancient within eukaryotes vs. those that have evolved more recently within specific lineages (Schlact et al, 2014). …”