During cellular division, most bacteria and archaea assemble a ring structure that coordinates the separation of mother and daughter cells. The primary component of this cytokinetic ring is FtsZ, a bacterial tubulin homologue. FtsZ polymers act as a scaffold, guiding the downstream assembly of a multi-protein machinery known as the divisome. In E. coli, the divisome acts as a master synchroniser; it coordinates the constriction of the inner membrane with simultaneous remodeling of the cell wall and the outer membrane.
Our goal is to achieve a mechanistic understanding of the divisome – specifically how its components assemble, interact and function collectively. Crucially, we also aim to reconstitute this system in vitro using liposomes. To do this, we have developed protocols to embed the core divisome complex within liposome membranes. Because the core divisome synthesises the bacterial cell wall on the exterior using the precursor lipid II, we will investigate this extracellular biosynthetic process. Additionally, we plan to incorporate FtsZ-ring components on the inside of the liposomes to direct cell wall synthesis and guide divisome localisation. A key question we seek to answer is whether liposome constriction is driven purely by the FtsZ-ring itself, or if it requires active peptidoglycan synthesis via the core divisome.
This project leverages an interdisciplinary toolkit spanning molecular biology, protein purification and state-of-the-art structural biology, including electron cryomicroscopy (cryo-EM) and electron cryotomography (cryo-ET) of both liposomes and intact bacterial cells. Aligned with the LMB’s mission in artificial biology, this research aims to successfully reconstitute liposome division in vitro, establishing foundational principles for downstream biological engineering applications.