Date/Time: 20th of November 2018, 13:00-14:00

Venue: Urban Science Building, room 3.032

Abstract

Gram-negative bacteria have in their periplasm a single layer of peptidoglycan, a net-like molecule made of glycan chains that are connected by short peptides. The peptidoglycan layer, also called sacculus, protects the cell from bursting due to the turgor and maintains the shape of the cell. During growth and cell division the sacculus is enlarged by the coordinated activities of peptidoglycan synthases (penicillin-binding proteins, PBPs) and hydrolases. However, the molecular mechanisms underlying peptidoglycan growth and its regulation are poorly understood, and there are discrepancies in the field about the function of main components.

Cytoskeletal proteins and associated cell morphogenesis proteins control peptidoglycan synthesis from inside the cell, within large cell envelope assemblies called elongasome and divisome. In Escherichia coli peptidoglycan growth is also regulated from the outside of the sacculus by outer membrane-anchored lipoproteins. LpoA and LpoB span the periplasm and are required to activate the inner membrane anchored peptidoglycan synthases, PBP1A and PBP1B, respectively. PBP1B-LpoB are involved with the synthesis of septal peptidoglycan during cell division. Their function is modulated by members of the Tol complex, which facilitates the constriction of the outer membrane during cell division, illustrating the intricate mechanisms by which the cell regulates peptidoglycan synthesis. I will also present recent findings on the interactions between peptidoglycan hydrolases and their regulators/adaptors and will discuss a model of how bacteria achieve robust peptidoglycan growth by dynamic and variable multi-protein complexes.

 

Biography

I studied chemistry at the Universities of Reutlingen (Germany) und Basel (Switzerland). After a PhD project at Max Planck Institute for Developmental Biology in Tübingen (Germany) I had postdoctoral positions at Rockefeller University (New York) and the University of Tübingen, where I became Assistant Professor in the year 2003. Since 2007 I am Reader and since 2009 Professor at the Centre for Bacterial Cell Biology at Newcastle University (UK). My research group works on the molecular mechanisms of bacterial cell wall synthesis in the model bacterium Escherichia coli and other bacteria. We study the activities and interactions of peptidoglycan enzymes and identify novel members of the pathway. We also investigate the spatiotemporal regulation of peptidoglycan growth and the mechanisms of cell shape generation. Finally, we determine the fine structure of peptidoglycan and cell wall architecture in Gram-positive and Gram-negative bacteria.