Poster Presentation International Peptide Symposium 2023

Development of Macrocyclic Peptide Inhibitors of Mycobacterium tuberculosis MurF by mRNA Display with Genetic Reprogramming (#222)

Patrick Carlos 1 2 , Charolotte Franck 1 2 , Emily Strong 3 , Isabel Barter 1 2 , Nicholas West 3 , Richard J Payne 1 2
  1. School of Chemistry and Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney
  2. Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Camperdown, NSW
  3. School of Chemistry and Molecular Biosciences, The University of Queensland, QLD

New therapeutics for the treatment of tuberculosis (TB) are vital in controlling the disease which is endemic in many developing countries. The problem with treating TB is the occurrence of multi-drug resistant TB (MDR-TB) and extensively-drug resistant TB (XDR-TB) that are infections caused by strains of Mycobacterium tuberculosis that are resistant to the first-line antibiotics or both first- and second-line drugs, respectively.1 One potential target for therapeutic design for TB is the MurF enzyme, which is critical for effective cell wall synthesis. MurF catalyses the ligation of two d-Ala residues to UDP-MurNAc-tripeptide to form UDP-MurNAc-pentapeptide, which is necessary to generate the peptidoglycan structure.2

Here, we will describe the use of Random non-standard Peptide Integrated Discovery (RaPID) mRNA display with genetic reprogramming on the M. tuberculosis MurF enzyme, which led to the discovery of several high-affinity thioether-linked cyclic peptide binders of the target.3 While these hits showed very high affinities to MurF, they showed poor antimycobacterial activity which we hypothesised was due to poor  permeability. To optimise our hits, we conjugated our best cyclic peptide inhibitors to Vitamin B12 to ‘hijack’ the Rv1819c (BacA homologue) transporter on Mycobacterium tuberculosis,  responsible for the uptake of Vitamin B12 from its environment.4, 5

  1. Seung, K. J.; Keshavjee, S.; Rich, M. L. Multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis. Cold Spring Harb. Perspect. Med. 2015, 5 (9).
  2. El Zoeiby, A.; Sanschagrin, F.; Levesque, R. C. Structure and function of the Mur enzymes: development of novel inhibitors. Mol. Microbiol. 2003, 47 (1), 1-12. DOI: 10.1046/j.1365-2958.2003.03289.x From NLM Medline.
  3. Passioura, T.; Suga, H. A RaPID way to discover nonstandard macrocyclic peptide modulators of drug targets. Chemical Communications 2017, 53 (12), 1931-1940.
  4. Gopinath, K.; Venclovas, Č.; Ioerger, T. R.; Sacchettini, J. C.; McKinney, J. D.; Mizrahi, V.; Warner, D. F. A vitamin B12 transporter in Mycobacterium tuberculosis. Open biology 2013, 3 (2), 120175.
  5. Równicki, M.; Wojciechowska, M.; Wierzba, A. J.; Czarnecki, J.; Bartosik, D.; Gryko, D.; Trylska, J. Vitamin B12 as a carrier of peptide nucleic acid (PNA) into bacterial cells. Sci. Rep. 2017, 7 (1), 7644.