Association of a Novel Mitochondrial Protein M19 with Mitochondrial Nucleoids

We have identified a novel mitochondrial protein, termed M19, by proteomic analysis of mitochondrial membrane proteins from HeLa cells. M19 is highly conserved among vertebrates, and possesses no homologous domains with other known proteins. By northern and western blotting, mouse M19 was shown to b...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 2009-11, Vol.146 (5), p.725-732
Main Authors: Sumitani, Megumi, Kasashima, Katsumi, Ohta, Eriko, Kang, Dongchon, Endo, Hitoshi
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Blotting, Northern
Blotting, Western
Conserved Sequence
DNA, Mitochondrial - metabolism
Gene Expression Regulation
HeLa Cells
Humans
Mice
mitochondria
mitochondrial nucleoids
mitochondrial protein
Mitochondrial Proteins - chemistry
Mitochondrial Proteins - genetics
Mitochondrial Proteins - metabolism
Molecular Sequence Data
mtDNA
Protein Binding
Vertebrates
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Summary:We have identified a novel mitochondrial protein, termed M19, by proteomic analysis of mitochondrial membrane proteins from HeLa cells. M19 is highly conserved among vertebrates, and possesses no homologous domains with other known proteins. By northern and western blotting, mouse M19 was shown to be expressed in various tissues, and to be especially abundant in the brain. Human M19 (hM19) is present in mitochondria, and protease-protection experiment showed it to be sublocalized in the matrix space. Carboxy-terminally tagged hM19 appeared as spotted signals within mitochondria and co-localized with signals arising from mitochondrial DNA (mtDNA), suggesting the inclusion of M19 in the mtDNA-protein complex (mitochondrial nucleoids). Fractionation of mitochondrial nucleoids from HeLa cells revealed that hM19 has a similar distribution pattern like that of known nucleoid components, such as mtSSB and PHBs, and surely exists in the nucleoid fraction. Furthermore, expression of M19 is closely related to the amount of mtDNA, because it was down-regulated in mtDNA-depleted ρ⁰ HeLa cells. These results indicate that M19 associates with the nucleoid and likely regulates the organization and metabolism of mtDNA.
ISSN:0021-924X
1756-2651
DOI:10.1093/jb/mvp118