Pr Jean-Francois Collet
Institut de Duve, Bruxelles
Gram-negative bacteria are defined by a complex cell envelope in which the outer membrane plays a central role in protection, nutrient exchange, and antibiotic resistance. This asymmetric lipid bilayer forms a robust permeability barrier, yet its biogenesis presents a striking challenge : all outer membrane components are synthesized in the cytoplasm or at the inner membrane and must be transported and assembled across the periplasm without direct energy input. In this talk, I will discuss how Gram-negative bacteria build their outer membrane and why this process is essential for cellular physiology. I will introduce the major pathways responsible for outer membrane assembly and highlight how their activities need to be coordinated to maintain envelope integrity. I will also present recent work showing that the outer membrane is not merely a passive barrier, but a mechanically active structure that enables the buildup of periplasmic pressure, a property critical for envelope stability and bacterial survival. Together, these findings underscore the outer membrane as a dynamic, multifunctional organelle and a promising target for future antibacterial strategies.