Bionanoscience (BN) seminar by prof.dr. Jan Löwe (MRC Laboratory of Molecular Biology, Cambridge) on "Towards molecular understanding of FtsZ-based bacterial cell division". The talk will start at 16:00h.

Abstract:
Cell division is a fundamental process of life. We focus on the molecular mechanisms employed by archaea and bacteria to divide and proliferate, and the processes’ evolutionary origins. Most bacteria and archaea divide using the tubulin homologue FtsZ as its central organiser. FtsZ forms a contracting filamentous ring-structure, the Z-ring. The Z-ring orchestrates cell wall synthesis by the divisome protein complex in walled bacteria, which in turn drives cell constriction and division.

We are making good progress towards a molecular understanding of the process and I will start by presenting recent work on the nature of FtsZ treadmilling that drives Z-ring function. Treadmilling requires a “cytomotive switch” – a conformational transition from monomer to polymer, that I will also highlight is conserved across the tree of life.

Central to the divisome is the peptidoglycan-synthesising protein complex FtsWI, which is regulated by the heterotrimer FtsQBL. We have recently solved the first structure of the activated divisome catalytic core complex FtsWIQBL by cryo-EM. The structure reveals details of the periplasmic interfaces within FtsWIQBL, including the positioning of FtsI by the coiled coil of FtsBL, as well as a transmembrane domain containing FtsWIBL, but not FtsQ. We were able to provide molecular mechanisms of a multitude of cell division phenotypes of known mutations and reveal a large conformational switch between presumably inactive and active states of the FtsWI core enzymes.

Finally, I will introduce very recent work on the Z-ring using newly developed technology that allows us to image entire cell division planes, including the Z-ring, by electron cryotomography and focussed ion beam (FIB) milling.