title: Origin and direction of replication in mitochondrial plasmid DNAs of broad bean, Vicia faba.
abstract: Broad bean (Vicia faba) mitochondrial DNA (mtDNA) includes three circular plasmids: mt-plasmid 1 (1,704 ntp), mt-plasmid 2 (1,695 ntp) and mt-plasmid 3 (1,476 ntp). Partially replicated circular forms of these mt-plasmids have been observed in electron microscope preparations. Restriction enzymes that cleave either mt-plasmid 2 (but not mt-plasmids 1 and 3) or mt-plasmid 3 (but not mt-plasmids 1 and 2) were used to generate linear forms of partially replicated mt-plasmid 2 and mt-plasmid 3 molecules. Analyses of these linearized replicative intermediates, observed by electron microscopy, indicated that in both mt-plasmid 2 and mt-plasmid 3 replication originates at a specific location and proceeds in the same, single direction around the molecules. The replication origins of mt-plasmid 2 and mt-plasmid 3 map close to sequences that can fold into hairpin structures.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City 84112.
authors.forename: J A
authors.initials: JA
authors.lastname: Wahleithner
authors.forename: D R
authors.initials: DR
authors.lastname: Wolstenholme
mesh_terms: D004261:DNA Replication; D004262:DNA Restriction Enzymes; D004270:DNA, Circular / Q000096:biosynthesis* / Q000235:genetics / Q000648:ultrastructure; D004272:DNA, Mitochondrial / Q000096:biosynthesis* / Q000235:genetics / Q000648:ultrastructure; D015252:Deoxyribonucleases, Type II Site-Specific; D007887:Fabaceae; D008854:Microscopy, Electron; D010946:Plants, Medicinal; D010957:Plasmids
chemical_list: D004270:DNA, Circular; D004272:DNA, Mitochondrial; D004262:DNA Restriction Enzymes; C025651:CCCGGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific