Poster Presentation The 42nd Lorne Conference on Protein Structure and Function 2017

Live Cell NMR: Mapping Cellular Responses to Antimicrobial Peptides in Live Bacteria by solid-state NMR (#282)

Sarah A Overall 1 , Marc-Antoine Sani 1 , Frances Separovic 1
  1. University of Melbourne, Melbourne, VIC, Australia

The rise of antibiotic resistant microorganisms has spurred the need to explore alternative antimicrobial agents for use in the clinic. Antimicrobial peptides are one such promising class of compounds that show great specificity towards microbial membranes with little resistance development. While the membrane activity of a variety of antimicrobial peptides (AMPs) is well documented, especially for cationic AMPs, their activity against other cellular components is largely unexplored. Here we use 31P solid-state NMR to investigate the activity of Maculatin 1.1 in intact live bacteria. We demonstrate the feasibility of using solid-state NMR techniques to selectively filter/isolate the signal of particular cellular components in whole cells including DNA and lipid membranes. We show that Maculatin 1.1 causes significant changes to the 31P signal of bacterial DNA suggesting a possible interaction between Maculatin 1.1 and DNA or elements that regulate the dynamics of DNA/RNA, a previously unknown effect of Maculatin 1.1 on bacteria. Maculatin 1.1 also caused a narrowing of the 31P signal from lipid membranes, indicative of increased lipid dynamics, consistent with the known membrane activity of Maculatin 1.1. We also observe the accumulation of a new phosphorus containing species in response to AMP treatment. The chemical shift of this species is consistent with phosphonate compounds, the production of which has not previously been associated with antimicrobial peptide treatment. It is clear from this work that the activity of Maculatin 1.1 goes beyond its membrane activity and that solid-state NMR is a powerful tool for investigating cellular responses to antimicrobial and drug treatments in live cells.