Biophysical Society Thematic Meeting | Stockholm 2022

Physical and Quantitative Approaches to Overcome Antibiotic Resistance

Wednesday Speaker Abstracts

LATERAL ORGANIZATION OF BACTERIAL MEMBRANES AS ANTIMICROBIAL TARGET Adéla Melcrová 1 ; Josef Melcr 2 ; Sourav Maity 1 ; Mariella Gabler 1 ; Jonne van der Eyden 1 ; Niels de Kok 3 ; Arnold Driessen 3 ; Siwert-Jan Marrink 2 ; Wouter Roos 1 ; 1 Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Molecular Biophysics, Groningen, The Netherlands 2 Groningen Biomolecular Sciences and Biotechnology Institute, Rijksuniversiteit Groningen, Molecular Dynamics, Groningen, The Netherlands 3 Groningen Biomolecular Sciences and Biotechnology Institute, Rijksuniversiteit Groningen, Molecular Microbiology, Groningen, The Netherlands Staphylococcus aureus is one of the leading human pathogens that developed strains resistant to commonly used antibiotics. Cell wall active antimicrobial peptides and their mimics— peptidomimetics—are promising tools in the fight against these infections. Here we scrutinize the functional mechanism of the antimicrobial action of a tetrapeptide based peptidomimetic with a potential in clinical use by combining Atomic Force Microscopy (AFM), High-Speed Atomic Force Microscopy (HS-AFM) and Molecular Dynamic (MD) simulations. In particular, we study its activity on membranes extracted from S. aureus cells, and on anionic membrane models matching our lipidomic analysis of the S. aureus extracts. Our joint experimental/theoretical approach reveals a two-step mechanism of its activity. First, the peptidomimetic self-assembles into stable aggregates with high selectivity for anionic membranes such as those of S. aureus. Second, the peptidomimetic incorporates into the membrane and thereby dissolves lateral membrane domains, affecting the membrane lateral organization. These lateral domains fulfil essential functions in living cells such as protein sorting, signaling, and cell-wall synthesis. Moreover, resistance of S. aureus to penicillin, methicillin, and related drugs is caused by low affinity penicillin binding proteins (PBP2a) that oligomerize in the membrane lateral domains. Disintegration of the domains leads to deletion of the vital membrane functions, and possible renewal of susceptibility to methicillin and penicillin. Last but not least, we observe that the active mechanism of the peptidomimetic resembles activity of small disinfectants such as ethanol, towards which no bacterial resistance has ever been developed. In summary, we identify and describe a new mechanism of antimicrobial activity that (i) deletes vital functions of the bacterial membrane, (ii) can possibly be used to renew the susceptibility to already known and tested antibiotics, and (iii) has the potential of no-resistance-generation.

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