3 years ago

The Oxidation State of [4Fe4S] Clusters Modulates the DNA-Binding Affinity of DNA Repair Proteins

The Oxidation State of [4Fe4S] Clusters Modulates the DNA-Binding Affinity of DNA Repair Proteins
Edmund C. M. Tse, Jacqueline K. Barton, Theodore J. Zwang
A central question important to understanding DNA repair is how certain proteins are able to search for, detect, and fix DNA damage on a biologically relevant time scale. A feature of many base excision repair proteins is that they contain [4Fe4S] clusters that may aid their search for lesions. In this paper, we establish the importance of the oxidation state of the redox-active [4Fe4S] cluster in the DNA damage detection process. We utilize DNA-modified electrodes to generate repair proteins with [4Fe4S] clusters in the 2+ and 3+ states by bulk electrolysis under an O2-free atmosphere. Anaerobic microscale thermophoresis results indicate that proteins carrying [4Fe4S]3+ clusters bind to DNA 550 times more tightly than those with [4Fe4S]2+ clusters. The measured increase in DNA-binding affinity matches the calculated affinity change associated with the redox potential shift observed for [4Fe4S] cluster proteins upon binding to DNA. We further devise an electrostatic model that shows this change in DNA-binding affinity of these proteins can be fully explained by the differences in electrostatic interactions between DNA and the [4Fe4S] cluster in the reduced versus oxidized state. We then utilize atomic force microscopy (AFM) to demonstrate that the redox state of the [4Fe4S] clusters regulates the ability of two DNA repair proteins, Endonuclease III and DinG, to bind preferentially to DNA duplexes containing a single site of DNA damage (here a base mismatch) which inhibits DNA charge transport. Together, these results show that the reduction and oxidation of [4Fe4S] clusters through DNA-mediated charge transport facilitates long-range signaling between [4Fe4S] repair proteins. The redox-modulated change in DNA-binding affinity regulates the ability of [4Fe4S] repair proteins to collaborate in the lesion detection process.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b07230

DOI: 10.1021/jacs.7b07230

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.