Strand switching during rolling circle replication of plasmid-like DNA circles in the mitochondria of the higher plant Chenopodium album (L.).
The structure of sigma-like mitochondrial DNA molecules prepared from suspension cultured cells of Chenopodium album (L.) was studied by electron microscopy. These molecules were highly variable in size, ranging from about 1 to 104 kb, and had single- and double-stranded regions typical for rolling circle replicating intermediates. Partial denaturation studies confirmed that these structures constitute rolling circles. Close inspection of the circle-tail junctions of the replication fork at high magnification suggests that in circles with a double-stranded tail, both strands of the tail seem to be covalently attached to the circle in about 27% of the molecules. This observation can be explained by a phenomenon called strand switching or strand splippage during rolling circle replication, similar to a mechanism proposed for bacterial replicons or in vitro replicating constructs harboring bacteriophage T4 replication origins.
Backert
S
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Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, Berlin, D-10115, Germany. backert@mpiib-berlin.mpg.de
D019663:Chenopodiaceae / Q000235:genetics* / Q000648:ultrastructure; D004261:DNA Replication; D004270:DNA, Circular / Q000096:biosynthesis* / Q000648:ultrastructure; D004272:DNA, Mitochondrial / Q000096:biosynthesis* / Q000648:ultrastructure; D018744:DNA, Plant / Q000096:biosynthesis* / Q000648:ultrastructure; D004277:DNA, Single-Stranded / Q000096:biosynthesis* / Q000648:ultrastructure; D016521:Electrophoresis, Gel, Pulsed-Field; D008854:Microscopy, Electron; D010957:Plasmids / Q000378:metabolism* / Q000648:ultrastructure
D004270:DNA, Circular; D004272:DNA, Mitochondrial; D018744:DNA, Plant; D004277:DNA, Single-Stranded