251. Hairpin and dimer structures of linear plasmid-like DNAs in mitochondria of Paramecium caudatum.
- Author
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Endoh H, Yazaki K, Takahashi M, and Tsukii Y
- Subjects
- Animals, DNA, Mitochondrial chemistry, DNA, Mitochondrial isolation & purification, DNA, Protozoan chemistry, DNA, Protozoan isolation & purification, Electrophoresis, Agar Gel, Microscopy, Electron, Nucleic Acid Denaturation, Repetitive Sequences, Nucleic Acid, Restriction Mapping, DNA, Mitochondrial ultrastructure, DNA, Protozoan ultrastructure, Mitochondria genetics, Nucleic Acid Conformation, Paramecium genetics, Plasmids genetics
- Abstract
The molecular structure of plasmid-like DNAs (designated type-II) which were isolated from mitochondria in the ciliated protozoan Paramecium caudatum was characterized. These type-II DNAs are always detected as a set of four kinds with sizes of 8.2, 4.1, 2.8 and 1.4 kb. The DNAs of 8.2 and 2.8 kb exist as dimers consisting of 4.1- and 1.4-kb monomer molecules, respectively. Electron microscopic observations indicated configurations of a hairpin structure that had a protruding end of single-stranded DNA in one terminus and a loop in the other terminus. The monomers stick together with base-pairing in opposite directions at the protruding end to form the dimers, suggesting the presence of inverted repeats. These unusual dimers may have a role in replication of the DNAs in which the monomers can serve as a primer for each other.
- Published
- 1994
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