The mitochondrial DNA replication bubble has not burst

• Published in: Trends in biochemical sciences (Amsterdam. Regular ed.) Vol. 28; no. 7; pp. 357 - 360
• Main Authors: Bogenhagen, Daniel F., Clayton, David A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2003
• Subjects: Animals; DNA Replication - genetics; DNA, Mitochondrial - biosynthesis; DNA, Mitochondrial - genetics; DNA, Mitochondrial - ultrastructure; Nucleic Acid Conformation; Replication Origin - genetics
• ISSN: 0968-0004; 1362-4326
• DOI: 10.1016/S0968-0004(03)00132-4

The isolation and physical characterization of mammalian mitochondrial DNA (mtDNA) as small, closed, circular DNA was reported more than 35 years ago. The relatively simple purification of mtDNA stimulated numerous studies of its replication mechanism. The model that has emerged, called the strand-displacement model, suggests that the two strands of mtDNA are each replicated in a continuous fashion from widely separated origins, requiring extensive displacement of parental DNA strands during leading-strand synthesis. Recently, two papers have reported candidates for putative replication intermediates (using 2D-gel electrophoresis) that the authors consider to be inconsistent with the strand-displacement model of mammalian mtDNA replication. In this article, we discuss the evidence in support of the strand-displacement model for mtDNA replication and suggest alternative explanations for some of the observations that led to this re-examination.