Human mitochondrial DNA nucleoids are linked to protein folding machinery and metabolic enzymes at the mitochondrial inner membrane.
Mitochondrial DNA (mtDNA) is packaged into bacterial nucleoid-like structures, each containing several mtDNA molecules. The distribution of nucleoids during mitochondrial fission and fusion events and during cytokinesis is important to the segregation of mitochondrial genomes in heteroplasmic cells bearing a mixture of wild-type and mutant mtDNA molecules. We report fractionation of HeLa cell mtDNA nucleoids into two subsets of complexes that differ in their sedimentation velocity and their association with cytoskeletal proteins. Pulse labeling studies indicated that newly replicated mtDNA molecules are evenly represented in the rapidly and slowly sedimenting fractions. Slowly sedimenting nucleoids were immunoaffinity purified using antibodies to either of two abundant mtDNA-binding proteins, TFAM or mtSSB. These two different immunoaffinity procedures yielded very similar sets of proteins, with 21 proteins in common, including most of the proteins previously shown to play roles in mtDNA replication and transcription. In addition to previously identified mitochondrial proteins, multiple peptides were observed for one novel DNA metabolic protein, the DEAH-box helicase DHX30. Antibodies raised against a recombinant fragment of this protein confirmed the mitochondrial localization of a specific isoform of DHX30.
Wang
Yousong
Y
Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, New York 11794-8651, USA.
Bogenhagen
Daniel F
DF
D000595:Amino Acid Sequence; D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D020033:Protein Isoforms
D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D020033:Protein Isoforms