Mammalian Mitochondrial DNA Replicates Bidirectionally from an Initiation Zone

Abstract

Previous data from our laboratory suggested that replication of mammalian mitochondrial DNA initiates exclusively at or near to the formerly designated origin of heavy strand replication, O H , and proceeds unidirectionally from that locus. New results obtained using twodimensional agarose gel electrophoresis of replication intermediates demonstrate that replication of mitochondrial DNA initiates from multiple origins across a broad zone. After fork arrest near O H , replication is restricted to one direction only. The initiation zone of bidirectional replication includes the genes for cytochrome b and NADH dehydrogenase subunits 5 and 6.

Replication Origin of Mitochondrial DNA in Insects

“…However, recently in human and mouse mtDNA, a symmetrical model of replication has been proposed (Holt et al 2000;Bowmaker et al 2003). A symmetrical model differs greatly from a strand-asynchronous, asymmetric model in respect to the position of the O R and the direction of replication.…”

Genetic aspects of mitochondrial genome evolution

“…Contrary to the orthodox model it is assumed that a replication bubble originates preferentially from an interval located near O H spanning approximately one quarter of the mitogenome (Bowmaker et al, 2003;Reyes et al, 2005).…”

The road to rack and ruin: selecting deleterious mitochondrial DNA variants

“…Well, this is not as fanciful as one might at first imagine. Although there is a long-standing designated origin of replication (O H ) in the major non-coding region (NCR) 1 , there is also evidence of initiation of DNA replication across a region of several kilobases adjacent to the NCR in mammals [18], and this initiation zone seems to peter out, rather than have a strict boundary. Indeed, in birds, initiation has been detected to occur in fragments throughout the mitochondrial genome [19].…”