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Discover the unique structures and rapid evolution of eukaryotes compared to archaea and bacteria. Reviewing molecular innovations and modifications in eukaryotic domains sheds light on the evolutionary path of these organisms.
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Comparative genomics and structural biology of the molecular innovations of eukaryotes L Aravind, LM Iyer, EV Koonin Presentation by Ruben Valas
LECA • Eukaryotes are very different than archaea and bacteria • There are no extant organisms that are pre-eukaryote like • This review paper examines some of the structures that are unique to eukaryotes
Mixing of archaea and bacteria Lopez-Garcia and David Moreira, 2006
Eukaryotes are very unique • Nucleus with linear chromosomes • Regulated cell cycle • Cytoskeleton system • Spliceosomal Introns • Distinct posttranslational regulation (ubiquitin) • Organelles such as mitochondria
All of this happened fast • Since all eukaryotes have these traits they must have evolved in a very short period of time • Cavalier-Smith says this is quantum evolution triggered by the mitochondrial symbiosis
Structure changed 3 ways • Ancient domains gained new functions • Ancient folds were tweaked to form new superfamilies • New folds emerged • This is a review paper, so this data comes from looking at the structures other papers identified
Their conclusions • They conclude most innovations are α-helical or chelation-supported • α-helical and metal-supported structures depend less on hydrogen bonding between distant residues • These structures can change rapidly
My Data • I can’t directly compare what we have because they aren’t only using SCOP FSFs • There are 60 SCOP FSFs that are only in eukaryotes and are in at least 58 of the 61 eukaryotes in Superfamily • If I use Dollo parsimony there are 123 or 145 FSFs in LECA depending on the tree
Its not all alpha • Their data is based on novel functions in eukaryotes, some new structures take on old functions • I find more beta and alpha+beta than metal binding, how these evolve rapidly still needs to be established • If alpha proteins can evolve so fast why aren’t these folds seen earlier?
Duplications • Many novel structures come from families of paralogs • These duplications appear to have happened before LECA • The mitchondrial symbiosis would act like a gene duplication for many genes