26/05/2025 - Marion MATHELIE-GUINLET : Unveiling the mechanisms of S. aureus pathogenicity - insights from Atomic Force Microscopy -

LES LUNDIS DE SAINT-ANTOINE

Bâtiment Kourilsky - 11h–12h

Salle des Conférences (Rez de Chaussée),

184 rue du Faubourg Saint-Antoine, Paris

***

LUNDI 26 MAI 2025

Unveiling the mechanisms of S. aureus pathogenicity
- insights from Atomic Force Microscopy -

Marion MATHELIE-GUINLET

 CR, CNRS - Institut de Chimie et Biologie des Membranes et Nanoobjets (CBMN), UMR 5248 CNRS

 Invitée par Ghislaine Guillemain équipe de Bruno FEVE (ghislaine.guillemain@inserm.fr)

Staphylococcus aureus is a bacterium infamous for the serious infections it causes, and its ability to resist multiple antibiotics, thus arising as a global major health problem. Its success as a pathogen comes from a variety of molecular tools either (i) embedded in the bacterial cell wall, like adhesins that promote adhesion and subsequently biofilm structuration, or (ii) secreted in the extracellular environment such as toxins and enzymes that damage host tissues.
To investigate the underlying mechanisms of S. aureus pathogenicity, atomic force microscopy (AFM) has evolved into a multifunctional toolbox allowing us to image and manipulate single cells and molecules with unprecedented resolution. In this seminar, focusing on AFM spectroscopic investigations, I will first discuss how the dynamical and nanomechanical behavior of adhesive proteins allows bacteria to modulate their adhesion depending on the mechanical loads, and thus initiate biofilm formation.
Next, I will explore how secreted S. aureus toxins, such as the phenol soluble modulins α3 (PSMα3) peptides, drive host cell death. Combining AFM imaging with traditional biophysical approaches, I will notably highlight the key roles of N-formylation and intermediate self-assembling entities, rather than mature PSMα3 amyloid fibrils, in dictating deleterious interactions with specific membrane lipids, likely underscoring its toxic function in vivo.
Through these in vitro and in cellulo approaches, I hope to convince you how advanced imaging techniques, like AFM, provide valuable insights into fundamental biological questions, particularly how S. aureus leverages its molecular arsenal to ultimately survive and thrive.