The phylogenetic position of the archaebacteria and the place of eukaryotes in the history of life remain a question of debate. Recent studies based on some protein-sequence data have obtained unusual phylogenies for these organisms. We therefore collected the protein sequences that were available with representatives from each of the major forms of life: the gram-negative bacteria, gram-positive bacteria, archaebacteria, and eukaryotes. Monophyletic, unrooted phylogenies based on these sequence data show that seven of 24 proteins yield a significant gram-positive-archaebacteria clade/gram-negative-eukaryotic clade. The phylogenies for these seven proteins cannot be explained by the traditional three-way split of the eukaryotes, archaebacteria, and eubacteria. Nine of the 24 proteins yield the traditional gram-positive-gram-negative clade/archaebacteria-eukaryotic clade. The remaining eight proteins give phylogenies that cannot be statistically distinguished. These results support the hypothesis of a chimeric origin for the eukaryotic cell nucleus formed from the fusion of an archaebacteria and a gram-negative bacteria.
Molecular phylogeny of the free-living archezoan Trepomonas agilis and the nature of the first eukaryote
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Intracellular bacterial symbiosis in the genus Sitophilus: the 'biological individual' concept revisited
Genes encoding the same three subunits of respiratory complex II are present in the mitochondrial DNA of two phylogenetically distant eukaryotes
The last eukaryotic common ancestor (LECA): acquisition of cytoskeletal motility from aerotolerant spirochetes in the Proterozoic Eon
Accounting for evolutionary rate variation among sequence sites consistently changes universal phylogenies deduced from rRNA and protein-coding genes
Variations of the mononucleotide and short oligonucleotide distributions in the genomes of various organisms
Impact of genomics on the understanding of microbial evolution and classification: the importance of Darwin's views on classification
Widespread use of the glu-tRNAGln transamidation pathway among bacteria. A member of the alpha purple bacteria lacks glutaminyl-trna synthetase.
What are archaebacteria: life's third domain or monoderm prokaryotes related to gram-positive bacteria? A new proposal for the classification of prokaryotic organisms
Evolution of the chaperonin families (Hsp60, Hsp10 and Tcp-1) of proteins and the origin of eukaryotic cells
Down-regulated RPS3a/nbl expression during retinoid-induced differentiation of HL-60 cells: a close association with diminished susceptibility to actinomycin D-stimulated apoptosis
Phylogenetic positions of 'Candidatus Phytoplasma asteris' and Spiroplasma kunkelii as inferred from multiple sets of concatenated core housekeeping proteins
Eukaryotic signature proteins of Prosthecobacter dejongeii and Gemmata sp. Wa-1 as revealed by in silico analysis
Recent advances in genomic sequencing has led to the discovery of new strains of Archaea and shed light on their evolutionary history. Discover the latest research on Archaeogenetics here.