title: Primer retention owing to the absence of RNase H1 is catastrophic for mitochondrial DNA replication.
abstract: Encoding ribonuclease H1 (RNase H1) degrades RNA hybridized to DNA, and its function is essential for mitochondrial DNA maintenance in the developing mouse. Here we define the role of RNase H1 in mitochondrial DNA replication. Analysis of replicating mitochondrial DNA in embryonic fibroblasts lacking RNase H1 reveals retention of three primers in the major noncoding region (NCR) and one at the prominent lagging-strand initiation site termed Ori-L. Primer retention does not lead immediately to depletion, as the persistent RNA is fully incorporated in mitochondrial DNA. However, the retained primers present an obstacle to the mitochondrial DNA polymerase γ in subsequent rounds of replication and lead to the catastrophic generation of a double-strand break at the origin when the resulting gapped molecules are copied. Hence, the essential role of RNase H1 in mitochondrial DNA replication is the removal of primers at the origin of replication.
authors.affiliation: Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; Medical Research Council (MRC) Mitochondrial Biology Unit, Cambridge CB19SY, United Kingdom;
authors.forename: J Bradley
authors.initials: JB
authors.lastname: Holmes
authors.affiliation: MRC National Institute for Medical Research, London NW71AA, United Kingdom;
authors.forename: Gokhan
authors.initials: G
authors.lastname: Akman
authors.affiliation: Medical Research Council (MRC) Mitochondrial Biology Unit, Cambridge CB19SY, United Kingdom;
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Wood
authors.affiliation: Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
authors.forename: Kiran
authors.initials: K
authors.lastname: Sakhuja
authors.affiliation: Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
authors.forename: Susana M
authors.initials: SM
authors.lastname: Cerritelli
authors.affiliation: MRC National Institute for Medical Research, London NW71AA, United Kingdom;
authors.forename: Chloe
authors.initials: C
authors.lastname: Moss
authors.affiliation: MRC National Institute for Medical Research, London NW71AA, United Kingdom;
authors.forename: Mark R
authors.initials: MR
authors.lastname: Bowmaker
authors.affiliation: BioMediTech and Tampere University Hospital, University of Tampere, FI-33014 Tampere, Finland; Research Program of Molecular Neurology, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Howard T
authors.initials: HT
authors.lastname: Jacobs
authors.affiliation: Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; ian.holt@crick.ac.uk robert.crouch@nih.gov.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Crouch
authors.affiliation: MRC National Institute for Medical Research, London NW71AA, United Kingdom; ian.holt@crick.ac.uk robert.crouch@nih.gov.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Holt
mesh_terms: D000818:Animals; D002460:Cell Line; D004247:DNA / Q000737:chemistry; D017931:DNA Primers / Q000737:chemistry*; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000737:chemistry*; D005091:Exons; D005347:Fibroblasts / Q000378:metabolism; D005838:Genotype; D006720:Homozygote; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism; D009711:Nucleotides / Q000737:chemistry; D012313:RNA / Q000737:chemistry; D000077278:RNA, Mitochondrial; D018741:Replication Origin; D016914:Ribonuclease H / Q000737:chemistry*
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial; D009711:Nucleotides; D000077278:RNA, Mitochondrial; D012313:RNA; D004247:DNA; D016914:Ribonuclease H; C078856:ribonuclease HI
keywords: DNA replication; RNase H; mitochondrial DNA; origin of replication; replication priming