Mukund Thattai

To protest the unending Bangalore roadworks, I created a game called Swalpa Adjust Maadi (Kannada for "please bear with the inconvenience"). You play the contractor digging up the roads, the residents are mute spectators who always lose! A new puzzle each day: mthattai.github.io/Swalpa-Adjus...

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

The "tubules-first model" suggests Asgard archaea should have internal membranes. Do they? Just as our review was being proofed, the Baum lab reported that the Asgard Y. umbracryptum has heterogeneous internal membranes! It's not yet clear which proteins regulate their formation.

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

Asgard archaea express proteins otherwise found only in eukaryotes. These "eukaryotic signature proteins" include many related to modern membrane traffic machinery. But "coatomers" like clathrin, COPI and COPII that generate vesicles in eukaryotes are absent. What were the ancestral cargo carriers?

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

Fleshing out this model: an ancestral Asgard archaeon eventually engulfs an alphaproteobacterium. This results in endosymbiotic mitochondria, as well as the first endomembrane with its own lumen. This endomembrane is the proto-endoplasmic reticulum, a portion of which is the nuclear envelope.

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

At the same time, Buzz and David Baum put forward their inside-out hypothesis for the origin of eukaryotes. In this model, an ancestral archaeon has surface protrusions that increase contact area with symbiotic bacteria. These protrusions eventually engulf the bacteria, which become mitochondria.

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

Modern sequence data shows that eukaryotes are chimeras of the two prokaryotic groups! Our metabolic genes have bacterial origins, our DNA replication, transcription and translation genes (including rRNA) have archaeal origins. But which present-day bacteria and archaea are our closest relatives?

The origin story of eukaryotes has more plot twists than a Hollywood blockbuster! 🧵 Read more in my new review: doi.org/10.1146/annu.... Only in the 1960s were the terms "prokaryote" and "eukaryote" formalized! As originally defined, eukaryotes had complex architectures, prokaryotes did not.

In 1967 Lynn Margulis argued that mitochondria were once free-living bacteria, symbiotically acquired by a host cell. Similar ideas had been proposed in the early 20th century, but Margulis came to them independently. Her influential paper was rejected by fifteen journals before being published.

How did eukaryotic cells get their Golgi, endosomes, lysosomes and other endomembrane compartments? We show that endomembrane evolution depends on long periods of neutral molecular exploration, punctuated by sudden leaps. New preprint: www.biorxiv.org/content/10.6...

Amazingly, this evolutionary process is able to reach complex endomembrane graphs with vesicle flows reminiscent of those found in modern eukaryotes.

How did eukaryotic cells get their Golgi, endosomes, lysosomes and other endomembrane compartments? We show that endomembrane evolution depends on long periods of neutral molecular exploration, punctuated by sudden leaps. New preprint: www.biorxiv.org/content/10.6...

The only evolutionary moves we allow are gene duplication, deletion, and simple mutations. We show that these are sufficient to convert simple endomembrane systems into more complex ones.

How did eukaryotic cells get their Golgi, endosomes, lysosomes and other endomembrane compartments? We show that endomembrane evolution depends on long periods of neutral molecular exploration, punctuated by sudden leaps. New preprint: www.biorxiv.org/content/10.6...

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. 🧵

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...

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. 🧵

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?

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. 🧵