title: Morphology and protein composition of the mitochondrial nucleoids in yeast cells lacking Abf2p, a high mobility group protein.
abstract: To elucidate the role of Abf2p, a major mitochondrial DNA-binding protein in the yeast Saccharomyces cerevisiae, we examined the morphology of the mitochondrial nucleoids (mt-nucleoids) in an ABF2-deficient mutant (Δabf2) in vivo and in vitro by 4',6-diamidino-2-phenylindole (DAPI) staining. The mt-nucleoids appeared as diffuse structures with irregular-size in Δabf2 cells that were grown to log phase in YPG medium containing glycerol, in contrast to the strings-of-beads appearance of mt-nucleoids in wild-type cells. In addition, DAPI-fluorescence intensity of the mt-nucleoids transmitted to the bud was significantly lower in Δabf2 cells than in wild-type cells at log phase. However, the lack of Abf2p did not affect the morphology or segregation of mitochondria. The protein composition of the mt-nucleoids isolated from Δabf2 cells grown to stationary phase in YPG medium was very similar to that of the mt-nucleoids isolated from wild-type cells cultured under the same conditions, except for the lack of Abf2p. These results together suggested that in log-phase cells, the lack of Abf2p influences not only the morphology of mt-nucleoids but also their transmission into the bud. On the other hand, our result suggested that in stationary-phase cells, the lack of Abf2p does not significantly alter the protein composition of the mt-nucleoids.
authors.affiliation: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan. miyakawa@yamaguchi-u.ac.jp
authors.forename: Isamu
authors.initials: I
authors.lastname: Miyakawa
authors.forename: Miwako
authors.initials: M
authors.lastname: Kanayama
authors.forename: Yuka
authors.initials: Y
authors.lastname: Fujita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
mesh_terms: D004271:DNA, Fungal / Q000032:analysis; D004272:DNA, Mitochondrial / Q000032:analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes; D007211:Indoles; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000737:chemistry / Q000648:ultrastructure; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D013367:Submitochondrial Particles / Q000737:chemistry* / Q000648:ultrastructure*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: C072843:ABF2 protein, S cerevisiae; D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D005456:Fluorescent Dyes; D007211:Indoles; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C007293:DAPI