MMP004: Deep-Sea Archaea and the Tree of Life with Thijs Ettema

Thijs Ettema of Uppsala University in Sweden talks with Jeff Fox about a deep-sea archaeon, named Lokiarchaeum for the underwater volcano between Greenland and Norway near where it was found, that might be related to the last common ancestor of eukaryotes.

“The shape-shifting deity ‘Loki’ is described as complex and confusing; thus, ‘Lokiarchaeum’ seems a very appropriate name for our typical prokaryote with a whole bunch of eukaryotic genes,” he says. “Importantly, the genes we found in Lokiarchaeum could have provided the archaeal ancestor of eukaryotes with a ‘starter kit’ for the cellular complexity typical in the eukaryotes we see today.” Genes usually associated with eukaryotes are found in Lokiarchaeota, including those enabling membrane remodeling and vesicular traffıcking, indicating that the onset of “cellular complexity was already underway before the acquisition of a mitochondrial endosymbiont.” The fındings favor a two-domain Tree of Life, in which eukaryotes are placed together with a diverse group of archaea known as the “TACK” superphylum because it includes Thaumarchaeota, Aigarchaeota, Crenarchaeota, and Korarchaeota, which share several signature proteins with eukaryotes.This story was featured in the August 2015 issue of Microbe magazine.