Download MendeleyInvestigations into the Antibacterial Mechanism of Action of Viridicatumtoxins.
Li, W., Li, L., Zhang, C., Cai, Y., Gao, Q., Wang, F., Cao, Y., Lin, J., Li, J., Shang, Z., Lin, W.(2020) ACS Infect Dis 6: 1759-1769
- PubMed: 32437130
- DOI: https://doi.org/10.1021/acsinfecdis.0c00031
- Primary Citation of Related Structures:
6LOI - PubMed Abstract:
Viridicatumtoxins are a rare class of tetracycline-like antibiotics that strongly inhibit drug-resistant Gram-positive bacteria. Although reported to exhibit in vitro inhibition activity to undecaprenyl pyrophosphate synthase (UPPS), an essential enzyme in bacterial cell wall synthesis, the biological targets and mechanism of action of viridicatumtoxins, especially the drug-target interactions, remain largely unknown. In this study, the structure of Enterococcus faecalis UPPS ( Efa UPPS) was first determined, uncovering that Efa UPPS can form not only a typical functional dimer but also an unexpected atypical dimer. We then observed that viridicatumtoxins A (VirA) and B (VirB) are able to bind to UPPSs of E. faecalis , S. aureus , and E. coli in a direct and high-affinity manner as evidenced by in vitro enzyme inhibition assay, surface plasmon resonance (SPR) binding analysis, and in vivo growth inhibition assay, demonstrating that viridicatumtoxins exert antibacterial effects through UPPS binding. The key amino acid residues involved in the interactions with VirA and VirB in Efa UPPS binding pocket were revealed by molecular docking studies, and further validated by site-directed mutagenesis. A single mutation of Efa UPPS at D29A, N31A, and R42A can obviously increase their affinities to VirA, while a single mutation at W228A conferred significant resistance to VirA. Moreover, translation inhibition assay showed that VirA and VirB can weakly inhibit E. coli 70S ribosome. The weak inhibition of ribosome was proposed to be attributed to steric hindrance between viridicatumtoxin ring F and 70S ribosome helix 34 by molecular docking study. Our structural, biochemical, and computational investigations on the interactions of viridicatumtoxins with UPPS and 70S ribosome not only disclosed the potential biological targets of viridicatumtoxins, but also provided a theoretical basis for structural optimization to make new viridicatumtoxin derivatives with improved antimicrobial activities.
Organizational Affiliation:
Department of Microbiology and Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China.
