Mitochondrial nucleoids from the yeast Candida parapsilosis: expansion of the repertoire of proteins associated with mitochondrial DNA.
Molecules of mitochondrial DNA (mtDNA) are packed into nucleic acid-protein complexes termed mitochondrial nucleoids (mt-nucleoids). In this study, we analysed mt-nucleoids of the yeast Candida parapsilosis, which harbours a linear form of the mitochondrial genome. To identify conserved as well as specific features of mt-nucleoids in this species, we employed two strategies for analysis of their components. First, we investigated the protein composition of mt-nucleoids isolated from C. parapsilosis mitochondria, determined N-terminal amino acid sequences of 14 proteins associated with the mt-nucleoids and identified corresponding genes. Next, we complemented the list of mt-nucleoid components with additional candidates identified in the complete genome sequence of C. parapsilosis as homologues of Saccharomyces cerevisiae mt-nucleoid proteins. Our approach revealed several known mt-nucleoid proteins as well as additional components that expand the repertoire of proteins associated with these cytological structures. In particular, we identified and purified the protein Gcf1, which is abundant in the mt-nucleoids and exhibits structural features in common with the mtDNA packaging protein Abf2 from S. cerevisiae. We demonstrate that Gcf1p co-localizes with mtDNA, has DNA-binding activity in vitro, and is able to stabilize mtDNA in the S. cerevisiae Deltaabf2 mutant, all of which points to a role in the maintenance of the C. parapsilosis mitochondrial genome. Importantly, in contrast to Abf2p, in silico analysis of Gcf1p predicted the presence of a coiled-coil domain and a single high-mobility group (HMG) box, suggesting that it represents a novel type of mitochondrial HMG protein.
Miyakawa
Isamu
I
Department of Physics, Biology, and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.
Okamuro
Akira
A
Department of Physics, Biology, and Informatics, Faculty of Science, Yamaguchi University, Yamaguchi 753-8512, Japan.
Kinsky
Slavomir
S
Departments of Biochemistry and Genetics, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia.
Visacka
Katarina
K
Departments of Biochemistry and Genetics, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia.
Tomaska
Lubomir
L
Departments of Biochemistry and Genetics, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia.
Nosek
Jozef
J
Departments of Biochemistry and Genetics, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia.
D000595:Amino Acid Sequence; D002175:Candida / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment
D004272:DNA, Mitochondrial; D005656:Fungal Proteins; D024101:Mitochondrial Proteins