Sep 14, 2014

An ectosymbiosis-based mechanism of eukaryogenesis

Jeffrey R JohnsonPedro Beltrao


The findings of a deep branching Microsporidia clade on the SSU rRNA tree, and diversity of sequence motifs in eukaryotic Hsp70s rendered invalid the endosymbiosis-first theory that mitosome- and hydrogenosome-containing amitochondriate eukaryotes (AMIs) arose from mitochondriate eukaryotes (MTEs) via reductive evolution. Instead, evidence of widespread ectosymbioses indicated that eukaryogenesis was started by an archaeal parent via its acquisition of archaeal proteins through 'accelerated gene adoption', and bacterial proteins from ectosymbionts including a clostridial ectosymbiont that supplied its [Fe] hydrogenase and pyruvate:ferredoxin oxidoreductase genes to the AMIs. Subsequent endosymbiosis with Tistrella gave rise to mitochondria with the participation of other alphaproteobacteria. The high frequencies of top similarity bitscores displayed by Giardia, Edhazardia and Trichomonas toward Aciduliprofundum boonei (Abo) pertaining to the enzymes of DNA biology, far surpassing the frequencies toward any Asgard or TACK archaeon, established Abo as the source of these enzymes in eukaryotes, and the archaeal parent of Eukarya.

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Mentioned in this Paper

Post-Translational Protein Processing
Protein Phosphorylation
Mass Spectrometry
Intercellular Communication Process
Drug Interactions

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