SKM 2023 – scientific programme
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BP: Fachverband Biologische Physik
BP 1: Membranes, Vesicles, Synthetic Cells
BP 1.6: Talk
Monday, March 27, 2023, 10:45–11:00, BAR Schö
Antimicrobial peptides: Revealing the Penetration Mechanism of Melittin in the Outer Membrane of Gram-Negative Bacteria — •Justus C. Stephani1, Luca Gerhards1, Ilia A. Solov'yov1, and Izabella Brand2 — 1Dept. of Physics, Carl von Ossietzky Universität, Germany — 2Dept. of Chemistry, Carl von Ossietzky Universität Oldenburg, Germany
Studying the interaction between antimicrobial peptides (AMPs) and bacterial membranes might aid to find new treatments against bacterial pathogens and even drug-resistant bacteria. The AMP melittin can target the complex structure of a cell membrane leading to membrane permeabilization via hole formation or disruption. We report on the results of electrochemical experiments, aided by modern, all-atom molecular dynamics simulations that reveal the role of lipopolysaccharides (LPS) in the outer membrane of gram-negative bacteria in melittin binding and penetration. We demonstrate that certain amino acid residues play a key role in the binding of melittin to the membrane and thereby stabilizing and preserving the confirmation of the peptide. With a combined method of polarization modulation infrared reflection-absorption spectroscopy (PM IRRAS) and the statistical analysis of C=O bond orientation in the peptide, we determine the orientation of melittin on the membrane and observed penetration of the N-Terminus of the peptide into the membrane and a formation of hydrogen bonds between the N-Terminus and carboxylate and phosphate of the LPS.