Origin of eukaryotic cell nuclei by symbiosis of Archaea in Bacteria is revealed by homology-hit ana

Abstract

The origin of eukaryotic cell nuclei by symbiosis of Archaea in Bacteria was proposed on the basis of the phylogenetic topologies of genes1,2,3. However, it was not possible to conclude whether or not the genes involved were authentic representative genes4. Furthermore, using the BLAST5 and FASTA6 programs, the similarity of open reading frame (ORF) groups between three domains (Eukarya, Archaea and Bacteria) was estimated at one threshold7,8. Therefore, their similarities at other thresholds could not be clarified. Here we use our newly developed 'homology-hit analysis' method, which uses multiple thresholds, to determine the origin of the nucleus. We removed mitochondria-related ORFs from yeast ORFs, and determined the number of yeast orthologous ORFs in each functional category to the ORFs in six Archaea and nine Bacteria at several thresholds (E-values) using the BLAST. Our results indicate that yeast ORFs related to the nucleus may share their origins with archaeal ORFs, whereas ORFs that are related to the cytoplasm may share their origins with bacterial ORFs. Our results thus strongly support the idea of nucleus symbiosis.

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Horiike, T., Hamada, K., Kanaya, S. et al. Origin of eukaryotic cell nuclei by symbiosis of Archaea in Bacteria is revealed by homology-hit analysis. Nat Cell Biol 3, 210–214 (2001). https://doi.org/10.1038/35055129

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