Biomaterial Database

Amphimeric mitochondrial genomes of petite mutants of yeast. II. A model for the amplification of amphimeric mitochondrial petite DNA. 1996

E Rayko, and R Goursot

Laboratoire de Génétique Moléculaire, Institut Jacques Monod, Paris, France.

A model for the recombination-directed replication and amplification of the mtDNA of amphimeric petite mutants of S. cerevisiae is proposed. Replication of an amphimeric master basic unit datA would be initiated in the inverted components a and A. The initiation of replication should be associated with the amphimeric structure of the master basic unit itself, but could be promoted by the presence of ori sequences or of sequences facilitating the initiation of replication in the inverted duplications. The amplification unit of amphimeric genomes is considered to be the double-stranded circular hetero-diamphimer datA-DaTA. Amplification of both diamphimeric strands involves an invasion of the 3' ends of the newly synthesized strands into symmetrical homologous duplex DNA regions promoting the continuation of replication, and leads to the accumulation of two ("flip" and "flop") types of multi-amphimers. We consider that this mode of amplification represents a modified rolling-circle mechanism. By analogy, we propose to call our model of amplification the "rocking-circle model". This model is likely to apply to other genomes organized as amphimeric structures.

UI	MeSH Term	Description	Entries
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D008957	Models, Genetic	Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Genetic Models,Genetic Model,Model, Genetic
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D011995	Recombination, Genetic	Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.	Genetic Recombination,Recombination,Genetic Recombinations,Recombinations,Recombinations, Genetic
D012091	Repetitive Sequences, Nucleic Acid	Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).	DNA Repetitious Region,Direct Repeat,Genes, Selfish,Nucleic Acid Repetitive Sequences,Repetitive Region,Selfish DNA,Selfish Genes,DNA, Selfish,Repetitious Region, DNA,Repetitive Sequence,DNA Repetitious Regions,DNAs, Selfish,Direct Repeats,Gene, Selfish,Repeat, Direct,Repeats, Direct,Repetitious Regions, DNA,Repetitive Regions,Repetitive Sequences,Selfish DNAs,Selfish Gene
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004270	DNA, Circular	Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)	Circular DNA,Circular DNAs,DNAs, Circular
D004271	DNA, Fungal	Deoxyribonucleic acid that makes up the genetic material of fungi.	Fungal DNA
D004272	DNA, Mitochondrial	Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.	Mitochondrial DNA,mtDNA