Biophysical Society Thematic Meeting | Ascona 2026

Mechanobiology of Infection

Poster Abstracts

21-POS Board 21 CHARACTERIZING THE MECHANICS OF MEMBRANE EXTRUSION DURING SHIGELLA VACUOLE MATURATION Oriana Robinson ; Arthur Lensen; Keith Egger; Jost Enninga Institut Pasteur, Cell Biology & Infection, Paris, France Invasion by intracellular bacterial pathogens of their host cells is facilitated by local reorganization of the plasma membrane and leads to the formation of a plasma membrane derived bacterial containing vacuole (BCV). For Shigella, the causative agent of bacterial dysentery, bacterial entry into non-phagocytic intestinal epithelial cells is facilitated via a syringe-like apparatus known as the Type 3 Secretion System (T3SS) which reprograms the host actin cytoskeleton around the contact site of the bacterium and allows for uptake into its BCV. Rapidly, Shigella ruptures the BCV and escapes into the cytosol where infection can proceed into neighboring epithelial cells. While BCV damage and rupture have been characterized in some detail, the events of early vacuolar formation and maturation leading to rupture are poorly understood. Membrane reshaping is actively driven by lipid composition and membrane-protein interactions. BAR (Bin/Amphyphisin/Rvs) domain-containing proteins specialize in membrane remodeling and curvature sensing and have been shown to be hijacked by other invasive bacterial pathogens for BCV maturation (e.g., Salmonella and SNX1/SNX3). Based on our super-fast timelapse imaging workflows and cryo-EM datasets, we identify BCV shrinkage and membrane extrusion as important events for early vacuolar maturation. Taking an integrative approach, we are elucidating the mechanical forces and molecular processes driving these events. To do this, we utilize advanced dynamic imaging methods including super-resolution techniques that allow us to link membrane reorganization with the insertion of the T3SS in the BCV membranes. Ultimately, this work will help further understand how Shigella manipulates host membranes for successful invasion and bacterial survival.

62