title: The root of the universal tree and the origin of eukaryotes based on elongation factor phylogeny.
abstract: The genes for the protein synthesis elongation factors Tu (EF-Tu) and G (EF-G) are the products of an ancient gene duplication, which appears to predate the divergence of all extant organismal lineages. Thus, it should be possible to root a universal phylogeny based on either protein using the second protein as an outgroup. This approach was originally taken independently with two separate gene duplication pairs, (i) the regulatory and catalytic subunits of the proton ATPases and (ii) the protein synthesis elongation factors EF-Tu and EF-G. Questions about the orthology of the ATPase genes have obscured the former results, and the elongation factor data have been criticized for inadequate taxonomic representation and alignment errors. We have expanded the latter analysis using a broad representation of taxa from all three domains of life. All phylogenetic methods used strongly place the root of the universal tree between two highly distinct groups, the archaeons/eukaryotes and the eubacteria. We also find that a combined data set of EF-Tu and EF-G sequences favors placement of the eukaryotes within the Archaea, as the sister group to the Crenarchaeota. This relationship is supported by bootstrap values of 60-89% with various distance and maximum likelihood methods, while unweighted parsimony gives 58% support for archaeal monophyly.
authors: Canadian Institute for Advanced Research and Department of Biochemistry, Dalhousie University, Halifax, Canada.
authors: S L
authors: SL
authors: Baldauf
authors: J D
authors: JD
authors: Palmer
authors: W F
authors: WF
authors: Doolittle
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000235:genetics; D016384:Consensus Sequence; D019143:Evolution, Molecular; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D020653:Peptide Elongation Factor G; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000235:genetics*; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D010944:Plants / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D000251:Adenosine Triphosphatases; D010444:Peptide Elongation Factor Tu