title: The inversion of the Control Region in three mitogenomes provides further evidence for an asymmetric model of vertebrate mtDNA replication.
abstract: Mitochondrial genomes are known to have a strong strand-specific compositional bias that is more pronounced at fourfold redundant sites of mtDNA protein-coding genes. This observation suggests that strand asymmetries, to a large extent, are caused by mutational asymmetric mechanisms. In vertebrate mitogenomes, replication and not transcription seems to play a major role in shaping compositional bias. Hence, one can better understand how mtDNA is replicated--a debated issue--through a detailed picture of mitochondrial genome evolution. Here, we analyzed the compositional bias (AT and GC skews) in protein-coding genes of almost 2,500 complete vertebrate mitogenomes. We were able to identify three fish mitogenomes with inverted AT/GC skew coupled with an inversion of the Control Region. These findings suggest that the vertebrate mitochondrial replication mechanism is asymmetric and may invert its polarity, with the leading-strand becoming the lagging-strand and vice-versa, without compromising mtDNA maintenance and expression. The inversion of the strand-specific compositional bias through the inversion of the Control Region is in agreement with the strand-displacement model but it is also compatible with the RITOLS model of mtDNA replication.
authors.affiliation: Department of Biochemistry, Genetics and Immunology, University of Vigo, Vigo, Spain; CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal.
authors.forename: Miguel M
authors.initials: MM
authors.lastname: Fonseca
authors.affiliation: CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal.
authors.forename: D James
authors.initials: DJ
authors.lastname: Harris
authors.affiliation: Department of Biochemistry, Genetics and Immunology, University of Vigo, Vigo, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Posada
mesh_terms: D000818:Animals; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics*; D054629:Genome, Mitochondrial; D008957:Models, Genetic; D010473:Perciformes / Q000235:genetics*; D018741:Replication Origin
chemical_list: D004272:DNA, Mitochondrial