title: Conserved sequence box II directs transcription termination and primer formation in mitochondria.
abstract: The human mitochondrial transcription machinery generates the RNA primers needed for initiation of heavy strand DNA synthesis. Most DNA replication events from the heavy strand origin are prematurely terminated, forming a persistent RNA-DNA hybrid, which remains annealed to the parental DNA strand. This triple-stranded structure is called the D-loop and encompasses the conserved sequence box II, a DNA element required for proper primer formation. We here use a purified recombinant mitochondrial transcription system and demonstrate that conserved sequence box II is a sequence-dependent transcription termination element in vitro. Transcription from the light strand promoter is prematurely terminated at positions 300-282 in the mitochondrial genome, which coincide with the major RNA-DNA transition points in the D-loop of human mitochondria. Based on our findings, we propose a model for primer formation at the origin of heavy strand DNA replication.
authors.affiliation: Department of Laboratory Medicine, Division of Metabolic Diseases, Karolinska Institutet, Novum, SE-141 86 Stockholm, Sweden.
authors.forename: Xuan Hoi
authors.initials: XH
authors.lastname: Pham
authors.forename: Géraldine
authors.initials: G
authors.lastname: Farge
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Shi
authors.forename: Martina
authors.initials: M
authors.lastname: Gaspari
authors.forename: Claes M
authors.initials: CM
authors.lastname: Gustafsson
authors.forename: Maria
authors.initials: M
authors.lastname: Falkenberg
mesh_terms: D001483:Base Sequence; D017124:Conserved Sequence; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics*; D006801:Humans; D008957:Models, Genetic; D011994:Recombinant Proteins / Q000235:genetics; D017421:Sequence Analysis; D014158:Transcription, Genetic
chemical_list: D004272:DNA, Mitochondrial; D011994:Recombinant Proteins