title: In vivo occupancy of mitochondrial single-stranded DNA binding protein supports the strand displacement mode of DNA replication.
abstract: Mitochondrial DNA (mtDNA) encodes for proteins required for oxidative phosphorylation, and mutations affecting the genome have been linked to a number of diseases as well as the natural ageing process in mammals. Human mtDNA is replicated by a molecular machinery that is distinct from the nuclear replisome, but there is still no consensus on the exact mode of mtDNA replication. We here demonstrate that the mitochondrial single-stranded DNA binding protein (mtSSB) directs origin specific initiation of mtDNA replication. MtSSB covers the parental heavy strand, which is displaced during mtDNA replication. MtSSB blocks primer synthesis on the displaced strand and restricts initiation of light-strand mtDNA synthesis to the specific origin of light-strand DNA synthesis (OriL). The in vivo occupancy profile of mtSSB displays a distinct pattern, with the highest levels of mtSSB close to the mitochondrial control region and with a gradual decline towards OriL. The pattern correlates with the replication products expected for the strand displacement mode of mtDNA synthesis, lending strong in vivo support for this debated model for mitochondrial DNA replication.
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Javier
authors.initials: J
authors.lastname: Miralles Fusté
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Wanrooij
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Jemt
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Örjan
authors.initials: Ö
authors.lastname: Persson
authors.affiliation: Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
authors.forename: Nasim
authors.initials: N
authors.lastname: Sabouri
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Claes M
authors.initials: CM
authors.lastname: Gustafsson
authors.affiliation: Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Falkenberg
mesh_terms: D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D000074002:DNA Polymerase gamma; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C504091:NABP2 protein, human; C499631:TFAM protein, human; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; C519567:POLRMT protein, human; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; C413027:POLG protein, human; C544932:POLG2 protein, human; D004265:DNA Helicases; C431576:TWNK protein, human