Biochemical properties of Caenorhabditis elegans HMG-5, a regulator of mitochondrial DNA.
Caenorhabditis elegans HMG-5, which is encoded by F45E4.9, contains two high mobility group (HMG) box domains and shows sequence similarity with mammalian mitochondrial transcription factor A (TFAM). In this study, using soaking RNA interference, we found that knockdown of HMG-5 reduced the amount of mtDNA in P0 hermaphrodites, suggesting it as functional orthologue of mammalian TFAM. We also examined the biochemical property of HMG-5 in mammalian cells and in vitro. We found that HMG-5 localized to the mitochondria in human cultured cells and was included in the NP-40-insoluble fraction in which mtDNA and TFAM were enriched. By immunoprecipitation analysis, HMG-5 was found to associate with human mitochondrial DNA (mtDNA) in the cells. In vitro binding experiment also showed that HMG-5 binds to C. elegans mtDNA and plasmid DNA, indicating its feature as a non-specific DNA-binding protein. Furthermore, it was found that HMG-5 can interact with itself. These results demonstrate that HMG5 shares similar biochemical properties with mammalian TFAM as a nucleoid factor. HMG-5 could be a good candidate for investigating mtDNA metabolism in multicellular organisms.
Department of Biochemistry, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan.
Megumi
M
Sumitani
Katsumi
K
Kasashima
Jitsuhiro
J
Matsugi
Hitoshi
H
Endo
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D034622:RNA Interference; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; C561090:HMG-5 protein, C elegans; D006609:High Mobility Group Proteins; D024101:Mitochondrial Proteins; D014157:Transcription Factors; C422562:mitochondrial transcription factor A
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