title: The strictly aerobic yeast Yarrowia lipolytica tolerates loss of a mitochondrial DNA-packaging protein.
abstract: Mitochondrial DNA (mtDNA) is highly compacted into DNA-protein structures termed mitochondrial nucleoids (mt-nucleoids). The key mt-nucleoid components responsible for mtDNA condensation are HMG box-containing proteins such as mammalian mitochondrial transcription factor A (TFAM) and Abf2p of the yeast Saccharomyces cerevisiae. To gain insight into the function and organization of mt-nucleoids in strictly aerobic organisms, we initiated studies of these DNA-protein structures in Yarrowia lipolytica. We identified a principal component of mt-nucleoids in this yeast and termed it YlMhb1p (Y. lipolytica mitochondrial HMG box-containing protein 1). YlMhb1p contains two putative HMG boxes contributing both to DNA binding and to its ability to compact mtDNA in vitro. Phenotypic analysis of a Δmhb1 strain lacking YlMhb1p resulted in three interesting findings. First, although the mutant exhibits clear differences in mt-nucleoids accompanied by a large decrease in the mtDNA copy number and the number of mtDNA-derived transcripts, its respiratory characteristics and growth under most of the conditions tested are indistinguishable from those of the wild-type strain. Second, our results indicate that a potential imbalance between subunits of the respiratory chain encoded separately by nuclear DNA and mtDNA is prevented at a (post)translational level. Third, we found that mtDNA in the Δmhb1 strain is more prone to mutations, indicating that mtHMG box-containing proteins protect the mitochondrial genome against mutagenic events.
authors: Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
authors: Jana
authors: J
authors: Bakkaiova
authors: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
authors: Kosuke
authors: K
authors: Arata
authors: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
authors: Miki
authors: M
authors: Matsunobu
authors: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
authors: Bungo
authors: B
authors: Ono
authors: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
authors: Tomoyo
authors: T
authors: Aoki
authors: Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
authors: Dana
authors: D
authors: Lajdova
authors: Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
authors: Martina
authors: M
authors: Nebohacova
authors: Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
authors: Jozef
authors: J
authors: Nosek
authors: Department of Biology, Faculty of Science, Yamaguchi University, Yamaguchi, Japan.
authors: Isamu
authors: I
authors: Miyakawa
authors: Departments of Genetics and Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic tomaska@fns.uniba.sk.
authors: Lubomir
authors: L
authors: Tomaska
mesh_terms: D000595:Amino Acid Sequence; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D055786:Gene Knockout Techniques; D054629:Genome, Mitochondrial; D024002:HMGB Proteins / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D025062:Yarrowia / Q000235:genetics* / Q000254:growth & development
chemical_list: C072843:ABF2 protein, S cerevisiae; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors