title: Morphology of mitochondrial nucleoids in respiratory-deficient yeast cells varies depending on the unit length of the mitochondrial DNA sequence.
abstract: We investigated the morphology of mitochondrial nucleoids (mt-nucleoids) and mitochondria in Saccharomyces cerevisiae rho(+) and rho(-) cells with DAPI staining and mitochondria-targeted GFP. Whereas the mt-nucleoids appeared as strings of beads in wild-type rho(+) cells at log phase, the mt-nucleoids in hypersuppressive rho(-) cells (HS40 rho(-) cells) appeared as distinct punctate structures. In order to elucidate whether the punctate mt-nucleoids are common to other rho(-) cells, we observed the mt-nucleoids in rho(-) strains that retain different unit lengths of the mitochondrial DNA (mtDNA) sequence. As a result, rho(-) cells that have long mtDNA sequences, of more than 30 kb, had mt-nucleoids with a strings-of-beads appearance in tubular mitochondria. In contrast, rho(-) cells that have short mtDNA sequences, of <1 kb, had punctate mt-nucleoids in tubular mitochondria. This indicates that the morphology of mt-nucleoids in rho(-) cells significantly varies depending on the unit length of their mtDNA sequence. Analyses of mt-nucleoids suggest that the punctate mt-nucleoids in HS40 rho(-) cells consist of concatemeric mtDNAs and oligomeric circular mtDNAs associated with Abf2p and other nucleoid proteins.
authors.affiliation: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okamoto
authors.affiliation: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Inai
authors.affiliation: Department of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yoshida 1677-1, Yamaguchi 753-8512, Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Gobancho, Chiyoda-ku, Tokyo 102-0076, Japan miyakawa@yamaguchi-u.ac.jp.
authors.forename: Isamu
authors.initials: I
authors.lastname: Miyakawa
mesh_terms: D004272:DNA, Mitochondrial / Q000235:genetics / Q000648:ultrastructure*; D004579:Electron Transport; D049452:Green Fluorescent Proteins / Q000032:analysis; D007211:Indoles / Q000032:analysis; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000648:ultrastructure*; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure*; D013194:Staining and Labeling
chemical_list: D004272:DNA, Mitochondrial; D007211:Indoles; D049452:Green Fluorescent Proteins; C007293:DAPI
keywords: Saccharomyces cerevisiae; mitochondria; mitochondrial nucleoids; respiratory deficiency; rho−