Redox signaling between DNA repair proteins for efficient lesion detection

Proc Natl Acad Sci U S A. 2009 Sep 8;106(36):15237-42. doi: 10.1073/pnas.0908059106. Epub 2009 Aug 31.

Abstract

Base excision repair (BER) enzymes maintain the integrity of the genome, and in humans, BER mutations are associated with cancer. Given the remarkable sensitivity of DNA-mediated charge transport (CT) to mismatched and damaged base pairs, we have proposed that DNA repair glycosylases (EndoIII and MutY) containing a redox-active [4Fe4S] cluster could use DNA CT in signaling one another to search cooperatively for damage in the genome. Here, we examine this model, where we estimate that electron transfers over a few hundred base pairs are sufficient for rapid interrogation of the full genome. Using atomic force microscopy, we found a redistribution of repair proteins onto DNA strands containing a single base mismatch, consistent with our model for CT scanning. We also demonstrated in Escherichia coli a cooperativity between EndoIII and MutY that is predicted by the CT scanning model. This relationship does not require the enzymatic activity of the glycosylase. Y82A EndoIII, a mutation that renders the protein deficient in DNA-mediated CT, however, inhibits cooperativity between MutY and EndoIII. These results illustrate how repair proteins might efficiently locate DNA lesions and point to a biological role for DNA-mediated CT within the cell.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA Damage / genetics*
  • DNA Glycosylases / metabolism*
  • DNA Repair*
  • Electron Transport
  • Escherichia coli
  • Microscopy, Atomic Force
  • Models, Biological*
  • Oxidation-Reduction
  • Signal Transduction / physiology*

Substances

  • DNA Glycosylases