title: Extensive Horizontal Transfer and Homologous Recombination Generate Highly Chimeric Mitochondrial Genomes in Yeast.
abstract: The frequency of horizontal gene transfer (HGT) in mitochondrial DNA varies substantially. In plants, HGT is relatively common, whereas in animals it appears to be quite rare. It is of considerable importance to understand mitochondrial HGT across the major groups of eukaryotes at a genome-wide level, but so far this has been well studied only in plants. In this study, we generated ten new mitochondrial genome sequences and analyzed 40 mitochondrial genomes from the Saccharomycetaceae to assess the magnitude and nature of mitochondrial HGT in yeasts. We provide evidence for extensive, homologous-recombination-mediated, mitochondrial-to-mitochondrial HGT occurring throughout yeast mitochondrial genomes, leading to genomes that are highly chimeric evolutionarily. This HGT has led to substantial intraspecific polymorphism in both sequence content and sequence divergence, which to our knowledge has not been previously documented in any mitochondrial genome. The unexpectedly high frequency of mitochondrial HGT in yeast may be driven by frequent mitochondrial fusion, relatively low mitochondrial substitution rates and pseudohyphal fusion to produce heterokaryons. These findings suggest that mitochondrial HGT may play an important role in genome evolution of a much broader spectrum of eukaryotes than previously appreciated and that there is a critical need to systematically study the frequency, extent, and importance of mitochondrial HGT across eukaryotes.
authors.affiliation: Department of Biological Sciences, Wayne State University.
authors.forename: Baojun
authors.initials: B
authors.lastname: Wu
authors.affiliation: Department of Biological Sciences, Wayne State University.
authors.forename: Adnan
authors.initials: A
authors.lastname: Buljic
authors.affiliation: Department of Biological Sciences, Wayne State University haow@wayne.edu.
authors.forename: Weilong
authors.initials: W
authors.lastname: Hao
mesh_terms: D001483:Base Sequence; D002678:Chimera / Q000235:genetics*; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D005800:Genes, Fungal; D054629:Genome, Mitochondrial; D059765:Homologous Recombination / Q000235:genetics*; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D029701:Saccharomyces cerevisiae Proteins
keywords: gene conversion; horizontal gene transfer; mitochondrial fusion