I set out to review the evolution of eukaryotic intracellular traffic, but along the way a new hypothesis came into focus: maybe the earliest membrane carriers were tubules, not coated vesicles! New preprint: ecoevorxiv.org/repository/v... Here’s the idea. 🧵
Eukaryotes arose via a merger between archaea and bacteria, with eukaryotic traits emerging gradually on the path from FECA (the archaeal first eukaryotic common ancestor) to LECA (last eukaryotic common ancestor). What if FECA was already an atypical archaeon with rudimentary eukaryote-like traits?
Asgard archaeal genomes encode many eukaryotic signature proteins, previously thought to be restricted to eukaryotes. In modern eukaryotes several of these ESPs are involved in membrane traffic. But Asgard archaea lack canonical vesicle coats. So what were these proteins doing in FECA?
A closer look shows that in present-day eukaryotes these Asgard ESPs are involved in the generation of tubular carriers at the ER, endosomes/TGN, and at the plasma membrane. In the review I discuss several new studies showing that Asgard versions of these proteins can indeed generate tubules!
Open questions remain. Intracellular membranes have not so far been confirmed in Asgard archaea. And what of the origin of other eukaryotic organelles? Could they be stabilised versions of ancient tubular carriers? I'd love to hear your thoughts! New preprint: ecoevorxiv.org/repository/v...
It's a great time to be studying eukaryogenesis, with so much new experimental data from diverse species. I want to thank several folks with whom I've been discussing these ideas for many years, especially @buzzbaum.bsky.social, @gautamdey.bsky.social, @ishier.bsky.social, @dackslabecb.bsky.social.
That is a tragically bad graphic.
That’s what I’ve been thinking!!
This might interest you: doi.org/10.1186/s129... Michael Overduin and I want to write a paper about the evolution of the PL code at some point. This will be helpful, thanks!