Structural basis for the inhibition of RecBCD by Gam and its synergistic antibacterial effect with quinolones.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28009252.
- Also identified by DOI 10.7554/eLife.22963 and PMC identifier 5218532.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Our previous paper (Wilkinson <i>et al</i>, 2016) used high-resolution cryo-electron microscopy to solve the structure of the <i>Escherichia coli</i> RecBCD complex, which acts in both the repair of double-stranded DNA breaks and the degradation of bacteriophage DNA. 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 <i>E. coli</i> or <i>Klebsiella pneumoniae</i> increases sensitivity to fluoroquinolones; antibacterials that kill cells by inhibiting topoisomerases and inducing double-stranded DNA breaks. Furthermore, fluoroquinolone-resistance in <i>K. pneumoniae</i> 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.
Medical subject headings
- Anti-Bacterial Agents
- DNA-Binding Proteins
- Drug Synergism
- Escherichia coli
- Exodeoxyribonuclease V
- Klebsiella pneumoniae
- Quinolones
- Viral Proteins