Breaching the great wall: peptidoglycan and microbial interactions

Once thought to be a process that occurred only in a few human pathogens, release of biologically active peptidoglycan fragments during growth by Gram-negative bacteria controls many types of bacterial interaction, including symbioses and interactions between microorganisms. This Perspective explores the role of peptidoglycan fragments in mediating a range of microbial-host interactions, and discusses the many systems in which peptidoglycan fragments released during bacterial growth might be active.