Host: Imre Berger

Abstract: The bacterial cell wall is important for survival and shape, and its biosynthetic mechanism is the target of beta-lactam antibiotics. The spread of resistant strains, however, has limited the usefulness of these drugs and calls for efforts towards studies of cell wall formation that could lead to the development of innovative treatments. The elongasome, or Rod system, is a protein complex that controls cell wall formation in non-spherical bacteria. MreC is a membrane-associated elongasome component that binds to Penicillin-Binding Protein 2 (PBP2), a protein that plays an essential role in cell survival. We employed X-ray crystallography and electron cryo-microscopy to determine the structures of a PBP2:MreC complex and of a self-associated form of MreC in atomic detail. I will present results that illustrate the importance of MreC’s capacity to interact with different proteins through the employment of different surfaces, which, if mutated, have a deleterious effect on bacterial survival and shape. MreC’s ability to alternate between self-association and interaction with the cell wall biosynthesis machinery plays a key role in the regulation of elongasome activity and sheds light on the importance of studying cell wall formation processes in light of the antibiotic resistance crisis.