Metal complexes for DNA-mediated charge transport

Abstract

In all organisms, oxidation threatens the integrity of the genome. DNA-mediated charge transport (CT) may play an important role in the generation and repair of this oxidative damage. In studies involving long-range CT from intercalating Ru and Rh complexes to 5′-GG-3′ sites, we have examined the efficiency of CT as a function of distance, temperature, and the electronic coupling of metal oxidants bound to the base stack. Most striking is the shallow distance dependence and the sensitivity of DNA CT to how the metal complexes are stacked in the helix. Experiments with cyclopropylamine-modified bases have revealed that charge occupation occurs at all sites along the bridge. Using Ir complexes, we have seen that the process of DNA-mediated reduction is very similar to that of DNA-mediated oxidation. Studies involving metalloproteins have, furthermore, shown that their redox activity is DNA-dependent and can be DNA-mediated. Long range DNA-mediated CT can facilitate the oxidation of DNA-bound base excision repair proteins to initiate a redox-active search for DNA lesions. DNA CT can also activate the transcription factor SoxR, triggering a cellular response to oxidative stress. Indeed, these studies show that within the cell, redox-active proteins may utilize the same chemistry as that of synthetic metal complexes in vitro, and these proteins may harness DNA-mediated CT to reduce damage to the genome and regulate cellular processes.

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© 2010 Elsevier B.V. Received 21 June 2010; accepted 5 September 2010. Available online 7 October 2010. We are grateful to NIH for their support of this research. We also thank our many colleagues for their efforts and insights, especially Harry Gray, whose seminal work on protein electron transfer, especially that using our favorite flash-quench methodology, inspired many experiments.

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Accepted Version - nihms240322.pdf

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