Biomaterial Database

The Holliday junction resolvase SpCCE1 prevents mitochondrial DNA aggregation in Schizosaccharomyces pombe. 2000

C L Doe, and F Osman, and J Dixon, and M C Whitby

Department of Biochemistry, University of Oxford, UK.

SpCCE1 (YDC2) from Schizosaccharomyces pombe is a DNA structure-specific endonuclease that resolves Holliday junctions in vitro. To investigate the in vivo function of SpCCE1 we made an Spcce1:ura4+ insertion mutant strain. This strain is viable and, despite being devoid of the Holliday junction resolvase activity that is readily detected in fractionated extracts from wild-type cells, exhibits normal levels of UV sensitivity and spontaneous or UV-induced mitotic recombination. In accordance with the absence of a nuclear phenotype, we show by fluorescence microscopy that a SpCCE1-GFP fusion localises exclusively to the mitochondria of S. pombe. In Saccharomyces cerevisiae the homologue of SpCCE1, CCE1, is known to function in the mitochondria where its role appears to be to remove recombination junctions and thus facilitate mitochondrial DNA segregation. A similar function can probably be attributed to SpCCE1 in S. pombe, since the majority of mitochondrial DNA from the Spcce1::ura4- strain is in an aggregated form apparently due to extensive interlinking of DNA molecules by recombination junctions. Surprisingly, this marked effect on the conformation of mitochondrial DNA results in little or no effect on proliferation or viability of the Spcce1::ura4+ strain. Possible explanations are discussed.

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
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
D002451	Cell Compartmentation	A partitioning within cells due to the selectively permeable membranes which enclose each of the separate parts, e.g., mitochondria, lysosomes, etc.	Cell Compartmentations,Compartmentation, Cell,Compartmentations, Cell
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
D004706	Endodeoxyribonucleases	A group of enzymes catalyzing the endonucleolytic cleavage of DNA. They include members of EC 3.1.21.-, EC 3.1.22.-, EC 3.1.23.- (DNA RESTRICTION ENZYMES), EC 3.1.24.- (DNA RESTRICTION ENZYMES), and EC 3.1.25.-.
D012568	Schizosaccharomyces	A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.	Fission Yeast,Schizosaccharomyces malidevorans,Schizosaccharomyces pombe,Yeast, Fission,S pombe,Fission Yeasts
D016254	Mutagenesis, Insertional	Mutagenesis where the mutation is caused by the introduction of foreign DNA sequences into a gene or extragenic sequence. This may occur spontaneously in vivo or be experimentally induced in vivo or in vitro. Proviral DNA insertions into or adjacent to a cellular proto-oncogene can interrupt GENETIC TRANSLATION of the coding sequences or interfere with recognition of regulatory elements and cause unregulated expression of the proto-oncogene resulting in tumor formation.	Gene Insertion,Insertion Mutation,Insertional Activation,Insertional Mutagenesis,Linker-Insertion Mutagenesis,Mutagenesis, Cassette,Sequence Insertion,Viral Insertional Mutagenesis,Activation, Insertional,Activations, Insertional,Cassette Mutagenesis,Gene Insertions,Insertion Mutations,Insertion, Gene,Insertion, Sequence,Insertional Activations,Insertional Mutagenesis, Viral,Insertions, Gene,Insertions, Sequence,Linker Insertion Mutagenesis,Mutagenesis, Linker-Insertion,Mutagenesis, Viral Insertional,Mutation, Insertion,Mutations, Insertion,Sequence Insertions
D045565	Holliday Junction Resolvases	Enzymes that recognize CRUCIFORM DNA structures and introduce paired incisions that help to resolve the structure into two DNA helices.	Holliday Junction Resolvase,Resolvases, Holliday Junction,Cruciform Cutting Endonuclease,Cruciform DNA Resolving Endonuclease,Endonuclease, Cruciform Cutting,Resolvase, Holliday Junction
D029701	Saccharomyces cerevisiae Proteins	Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.	Baker's Yeast Proteins,S cerevisiae Proteins