Structural basis for the inhibition of RecBCD by Gam and its synergistic antibacterial effect with quinolones
- Imperial College London, United Kingdom
- University of Bristol, United Kingdom
Abstract
In previous work we used high-resolution cryo-electron microscopy to solve the structure of the Escherichia coli RecBCD complex, which acts in both the repair of double-stranded DNA breaks and the degradation of bacteriophage DNA (Wilkinson et al, 2016). To counteract the latter activity, bacteriophage λ encodes a small protein inhibitor called Gam that binds to RecBCD and inactivates the complex. Here, we show that Gam inhibits RecBCD by competing at the DNA-binding site. The interaction surface is extensive and involves molecular mimicry of the DNA substrate. We also show that expression of Gam in E. coli or Klebsiella pneumoniae increases sensitivity to fluoroquinolones; antibacterials that kill cells by inhibiting topoisomerases and inducing double-stranded DNA breaks. Furthermore, fluoroquinolone-resistance in K. pneumoniae clinical isolates is reversed by expression of Gam. Together, our data explain the synthetic lethality observed between topoisomerase-induced DNA breaks and the RecBCD gene products, suggesting a new co-antibacterial strategy.
Article and author information
Author details
Mark Simon Dillingham
Funding
Wellcome (095519/B/11/Z)
- Dale B Wigley
Medical Research Council (MR/N009258/1)
- Dale B Wigley
Cancer Research UK (A12799)
- Dale B Wigley
Wellcome (100401/Z/12/Z)
- Mark Simon Dillingham
Engineering and Physical Sciences Research Council (EP/M027546/1)
- Matthew B Avison
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Wilkinson et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Structural basis for the inhibition of RecBCD by Gam and its synergistic antibacterial effect with quinolones
eLife 5:e22963.
https://doi.org/10.7554/eLife.22963
