DNA Helicase from Mammalian Mitochondria
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In spite of the fact that a DNA helicase is clearly required for the predominantly leading-strand synthesis occurring during mammalian mtDNA replication, no such activity has heretofore been identified. We report the characterization of a mammalian mitochondrial DNA helicase isolated from bovine brain tissue. The sucrose gradient-purified mitochondria in which the activity was detected had less than 1 part in 2500 nuclear contamination according to Western blot analysis using nuclear- and mitochondrial-specific probes. Mitochondrial protein fractionation by DEAE-Sephacel chromatography yielded a DNA helicase activity dependent upon hydrolysis of ATP or dATP but not other NTPs or dNTPs. The mitochondrial helicase unwound 15- and 20-base oligonucleotides but was unable to unwind 32-base or longer oligonucleotides, and the polarity of the unwinding is 3'-to-5' with respect to the single-stranded portion of the partial duplex DNA substrate. This direction of unwinding would place the bovine mitochondrial helicase on the template strand ahead of DNA polymerase gamma during mtDNA replication, a situation analogous to that of the Rep helicase of Escherichia coli during leading-strand DNA synthesis of certain bacteriophages.
Helicases as molecular motors: An insight.
Tuteja N, Tuteja R Physica A. 2020; 372(1):70-83.
PMID: 32288077 PMC: 7127012. DOI: 10.1016/j.physa.2006.05.014.
Brosh Jr R, Matson S Genes (Basel). 2020; 11(3).
PMID: 32120966 PMC: 7140857. DOI: 10.3390/genes11030255.
Wong V, Langley B Neurosci Lett. 2016; 625:26-33.
PMID: 27155457 PMC: 4915732. DOI: 10.1016/j.neulet.2016.04.009.
Structure, function and evolution of the animal mitochondrial replicative DNA helicase.
Kaguni L, Oliveira M Crit Rev Biochem Mol Biol. 2015; 51(1):53-64.
PMID: 26615986 PMC: 4733421. DOI: 10.3109/10409238.2015.1117056.
Prokaryotic and eukaryotic DNA helicases. Essential molecular motor proteins for cellular machinery.
Tuteja N, Tuteja R Eur J Biochem. 2004; 271(10):1835-48.
PMID: 15128294 PMC: 7164108. DOI: 10.1111/j.1432-1033.2004.04093.x.