Session 2D Lectures by Fellows/Associates

Break before make - how do bacteria make their cell walls

Bacteria are a large group of ubiquitous unicellular microorganisms. To protect themselves against both extracellular stress and intracellular osmotic pressure, most bacteria are surrounded by a cell wall that consists of an elastic, mesh-like polymer called peptidoglycan (PG) sacculus. PG is a single large macromolecule made up of multiple overlapping glycan strands interlinked by short peptide chains and forms a net-like structure around the bacterial cytoplasmic membrane. Since, PG completely encases the cytoplasmic membrane, cleavage of peptide cross-links is a prerequisite to open the mesh and make space to incorporate nascent glycan strands for its successful expansion during growth of a cell. Using a Gram-negative rod-shaped bacterium, Escherichia coli as a model system, our lab has shown that the step of cross-link cleavage mediated by specialized endopeptidases is essential for the expansion of PG sacculus and hence for bacterial growth. Overall, our study signifies the role of PG hydrolysis in bacterial cell wall synthesis thereby rendering it an alternative drug target for development of novel antimicrobial agents.