Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Antibiotic discovery by targeting bacterial RNA polymerase holoenzyme formation (#52)

Jiang Liu 1 , Xiao Yang 2 , Cong Ma 1
  1. Hong Kong Polytechnic University, Hung Hom, KLN, Hong Kong
  2. Department of Microbiology, The Chinese University of Hong Kong, Shatin, NT, Hong Kong

Background: Antimicrobial resistance emerges to become a serious threat to antimicrobial therapy. Novel antimicrobial agents are urgently required to eradicate current drug-resistant bacteria and are expected to ideally suppress new resistance generation. Protein-protein interactions (PPI) commonly exist in bacteria. Drugs targeting PPI would theoretically increase the difficulty of mutations and fitness costs, therefore reducing the resistance generation.1

Methods: Bacterial transcription is a valid but underutilized drug target.2 We studied the PPI between RNA polymerase (RNAP) and the housekeeping sigma factor, which is essential for RNAP holoenzyme formation and the initiation of RNA synthesis.3 Through structure-based drug design, we developed a series of benzoic acid derivatives to mimic the structure of sigma factor at the critical binding site with RNAP.4 This series of small-molecule compounds was coined sigmacidin to acknowledge the drug design strategy mimicking sigma factor and the benzoic acid structure.

Results: Sigmacidin compounds showed inhibitory activity to interrupt the RNAP-sigma PPI and reduce RNA synthesis and toxin release. They also exhibited excellent antimicrobial activity against Gram-positive bacteria including antibiotic-resistant strains such as MRSA and VRSA. The 30-day serial passage did not show resistance generation. In vivo pharmacokinetic studies demonstrated oral availability, and the drug efficacy was also proven in an MRSA-infected peritoneal sepsis model.

Conclusions: Targeting PPI is a valid strategy for antimicrobial drug discovery. Sigmacidins are currently under preclinical studies for further drug development.

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  1. Modulators of protein–protein interactions as antimicrobial agents. Kahan, R.; Worm, D. J.; de Castro, G. V. ; Ng, S.; Barnard. A. RSC Chem. Biol. 2021, 2, 387.
  2. Bacterial transcription as a target for antibacterial drug development. Ma, C.; Yang, X.; Lewis, P. J. Microbiol. Mol. Biol. Rev. 2016, 80, 139.
  3. Structural basis of transcription initiation: an RNA polymerase holoenzyme-DNA complex. Murakami, K. S.; Masuda, S.; Campbell, E. A.; Muzzin, O.; Darst, S. A. Science 2002, 296, 1285.
  4. Discovery of antibacterials that inhibit bacterial RNA polymerase interactions with sigma factors. Ye, J.; Chu, A. J.; Harper, R.; Chan, S. T.; Shek, T. L.; Zhang, Y.; Ip, M.; Sambir, M.; Artsimovitch, I.; Zuo, Z.; Yang, X.; Ma, C. J. Med. Chem. 2020, 63, 7695.