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DNA Oxidation by Charge Transport in Mitochondria

Merino, Edward J. and Barton, Jacqueline K. (2008) DNA Oxidation by Charge Transport in Mitochondria. Biochemistry, 47 (6). pp. 1511-1517. ISSN 0006-2960. doi:10.1021/bi701775s.

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Sites of oxidative DNA damage in functioning mitochondria have been identified using a rhodium photooxidant as a probe. Here we show that a primer extension reaction can be used to monitor oxidative DNA damage directly in functioning mitochondria after photoreaction with a rhodium intercalator that penetrates the intact mitochondrial membrane. The complex [Rh(phi)_2bpy]Cl_3 (phi = 9,10-phenanthrenequinonediimine) binds to DNA within the mitochondria and, upon irradiation, initiates DNA oxidation reactions. Significantly, piperidine treatment of the mitochondria leads to protein-dependent primer extension stops spaced every ∼20 base pairs. Hence, within the mitochondria, the DNA is well covered and packaged by proteins. Photolysis of the mitochondria containing [Rh(phi)_2bpy]^(3+) leads to oxidative DNA damage at positions 260 and 298; both are mutational hot spots associated with cancers. The latter position is the 5‘-nucleotide of conserved sequence block II and is critical to replication of the mitochondrial DNA. The oxidative damage is found to be DNA-mediated, utilizing a charge transport mechanism, as the Rh binding sites are spatially separated from the oxidation-prone regions. This long-range DNA-mediated oxidation occurs despite protein association. Indeed, the oxidation of the mitochondrial DNA leads not only to specific oxidative lesions, but also to a corresponding change in the protein-induced stops in the primer extension. Mitochondrial DNA damage promotes specific changes in protein−DNA contacts and is thus sensed by the mitochondrial protein machinery.

Item Type:Article
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URLURL TypeDescription Information
Barton, Jacqueline K.0000-0001-9883-1600
Additional Information:© 2008 American Chemical Society. Received August 30, 2007; Revised Manuscript Received November 20, 2007. Publication Date (Web): January 12, 2008. We are grateful to the NIH (Grant GM49216) for their financial support of this research including a minority postdoctoral fellowship to E.J.M.
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NIH Postdoctoral FellowshipUNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:20160229-120833212
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Official Citation:DNA Oxidation by Charge Transport in Mitochondria Edward J. Merino and Jacqueline K. Barton Biochemistry 2008 47 (6), 1511-1517 DOI: 10.1021/bi701775s
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64852
Deposited By: Ruth Sustaita
Deposited On:29 Feb 2016 20:58
Last Modified:10 Nov 2021 23:36

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