Poster Presentation Australasian RNA Biology and Biotechnology Association 2024 Conference

Developing macrocyclic peptide inhibitors against a bacterial receptor for antibiotic leads (#151)

Madeline S McRae 1 , Patrick Carlos 2 , Lorna Wilkinson-White 3 , Anthony P Duff 4 , Toby Passioura 3 , Richard J Payne 2 , Sandro F Ataide 1 , Ann H Kwan 1
  1. School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
  2. School of Chemistry, The University of Sydney, Sydney, NSW, Australia
  3. Sydney Analytical Core Facility, University of Sydney, Sydney, NSW, Australia
  4. National Deuteration Facility, ANSTO, Lucas Heights, NSW, Australia

The rapid global emergence of antibiotic resistance in the past decades necessitates the development of new antibiotics with a novel mechanism. FtsY, a receptor protein for prokaryotic signal recognition particle (SRP) is a potential antibiotic target due to its essential role in protein folding and proper targeting of nascent polypeptide to its cellular destination. SRP and its receptor (SR) are functionally conserved across all living organisms, but the NG-domain of FtsY in prokaryotes are uniquely engaged in a protein:RNA interaction with its SRP partner while its eukaryotic homolog, SRĪ±-NG, binds other SRP proteins. The FtsY-NG:RNA interaction has never been targeted before will open up opportunities for novel antibiotic development.

As the FtsY-NG:RNA interaction interface is large, shallow and dynamic, we have used the RaPID (Random nonstandard Peptides Integrated Discovery) technique that allows screening of up to 1013 cyclic peptides against a target to develop inhibitors. A peptide that binds to the FtsY-NG RNA-interaction site with high nanomolar affinities has been identified [1]. Here, I will present the biophysical and biochemical studies, including Surface Plasmon Resonance, Nuclear Magnetic Resonance spectroscopy, X-ray crystallography and gel shift assays to provide insights into molecular interactions of cyclic peptides with FtsY-NG. Additionally, in-house whole-cell screening protocol was established to observe the antimicrobial activities of the peptide and its variants. Collectively, these findings aid in the specificity and affinity optimisation of the peptides for FtsY-NG with the plan to further develop them into antibiotic leads. Furthermore, these results signify the prospect of using RaPID system for developing inhibitors against other RNA-binding proteins.

  1. Passioura, T., and Suga, H., A RaPID way to discover nonstandard macrocyclic peptide modulators of drug targets. Chem. Commun., 2017. 53: 1931-1940.