Chemical inhibition of MrkH-dependent activation of type 3 fimbriae synthesis and biofilm formation by Klebsiella pneumoniae

  • NPJ Biofilms Microbiomes. 2025 Nov 20;11(1):212. doi: 10.1038/s41522-025-00834-3.
Jonathan J Wilksch  #  1  2 ,  Jason W H Tan  #  1 ,  Tracy L Nero  #  3 ,  Dianna M Hocking  1  4 ,  Vicki Bennett-Wood  1 ,  Nancy Wang  1  4 ,  Stefanie-Ann Zavras  5 ,  Carl H Schiesser  5 ,  Marija Tauschek  1 ,  Mark A Schembri  6 ,  Trevor Lithgow  2 ,  Elizabeth L Hartland  1  7 ,  Roy M Robins-Browne  1 ,  Michael W Parker  3  8 ,  Ji Yang  1 ,  Richard A Strugnell  9  10
Affiliations
  • 1. Department of Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Parkville, VIC, Australia.
  • 2. Infection & Immunity Program, Biomedicine Discovery Institute & Department of Microbiology, Monash University, Clayton, VIC, Australia.
  • 3. Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia.
  • 4. Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia.
  • 5. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology and the School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia.
  • 6. Institute for Molecular Bioscience (IMB), and School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia.
  • 7. Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Australia and Department of Molecular and Translational Science, Monash University, Clayton, VIC, Australia.
  • 8. Structural Biology Laboratory, St Vincent's Institute of Medical Research, Melbourne, VIC, Australia.
  • 9. Department of Microbiology and Immunology, The University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Parkville, VIC, Australia. [email protected].
  • 10. Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia. [email protected].
  • # Contributed equally.
PMID: 41266360 DOI: 10.1038/s41522-025-00834-3
Abstract

Biofilm formation by Klebsiella pneumoniae is mediated by the type 3 fimbriae Mrk, and regulated by MrkH and 3',5'-cyclic diguanylic acid (c-di-GMP). We sought to identify specific chemical inhibitors of K. pneumoniae biofilm formation that reduced the activity of MrkH. A compound N-(3-cyano-5,6,7,8-tetrahydro-4H-cyclohepta[b]thien-2-yl)-2-methoxybenzamide, JT71, reduced K. pneumoniae mrkA promoter activity and biofilm formation by 50% without affecting cell viability. Western blot analysis, hemagglutination assays, electron microscopy and qPCR showed that JT71 reduced type 3 fimbriae production, and transcription of mrkA and mrkH. JT71 demonstrated activity against Other clinical and multi-drug resistant K. pneumoniae isolates, and a type 3 fimbriate-positive Citrobacter koseri strain. In silico molecule docking was used to illustrate that JT71 could bind directly to the MrkH protein and block its activity. JT71 possesses promising drug-likeness properties and is non-toxic to mammalian cells. Chemical inhibition of transcriptional regulators that control fimbriae expression can inhibit Bacterial biofilm formation.

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