title: Evolution of mitochondria reconstructed from the energy metabolism of living bacteria.
abstract: The ancestors of mitochondria, or proto-mitochondria, played a crucial role in the evolution of eukaryotic cells and derived from symbiotic α-proteobacteria which merged with other microorganisms - the basis of the widely accepted endosymbiotic theory. However, the identity and relatives of proto-mitochondria remain elusive. Here we show that methylotrophic α-proteobacteria could be the closest living models for mitochondrial ancestors. We reached this conclusion after reconstructing the possible evolutionary pathways of the bioenergy systems of proto-mitochondria with a genomic survey of extant α-proteobacteria. Results obtained with complementary molecular and genetic analyses of diverse bioenergetic proteins converge in indicating the pathway stemming from methylotrophic bacteria as the most probable route of mitochondrial evolution. Contrary to other α-proteobacteria, methylotrophs show transition forms for the bioenergetic systems analysed. Our approach of focusing on these bioenergetic systems overcomes the phylogenetic impasse that has previously complicated the search for mitochondrial ancestors. Moreover, our results provide a new perspective for experimentally re-evolving mitochondria from extant bacteria and in the future produce synthetic mitochondria.
authors.affiliation: Italian Institute of Technology, Genoa, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Degli Esposti
authors.affiliation: Department of Food, Environmental and Evolutionary Sciences, University of Milan, Milan, Italy.
authors.forename: Bessem
authors.initials: B
authors.lastname: Chouaia
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Comandatore
authors.affiliation: Department of Food, Environmental and Evolutionary Sciences, University of Milan, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Crotti
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Sassera
authors.affiliation: Italian Institute of Technology, Genoa, Italy.
authors.forename: Patricia Marie-Jeanne
authors.initials: PM
authors.lastname: Lievens
authors.affiliation: Department of Food, Environmental and Evolutionary Sciences, University of Milan, Milan, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Daffonchio
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica, University of Milan, Milan, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Bandi
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D019143:Evolution, Molecular; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny