Cell wall elongation mode in Gram-negative bacteria is determined by peptidoglycan architecture

Abstract

Cellular integrity and morphology of most bacteria is maintained by cell wall peptidoglycan, the target of antibiotics essential in modern healthcare. It consists of glycan strands, cross-linked by peptides, whose arrangement determines cell shape, prevents lysis due to turgor pressure and yet remains dynamic to allow insertion of new material, and hence growth. The cellular architecture and insertion pattern of peptidoglycan have remained elusive. Here we determine the peptidoglycan architecture and dynamics during growth in rod-shaped Gram-negative bacteria. Peptidoglycan is made up of circumferentially oriented bands of material interspersed with a more porous network. Super-resolution fluorescence microscopy reveals an unexpected discontinuous, patchy synthesis pattern. We present a consolidated model of growth via architecture-regulated insertion, where we propose only the more porous regions of the peptidoglycan network that are permissive for synthesis.

Abstract

Bacterial cell wall peptidoglycan is essential for viability and shape determination. Using high-resolution microscopy, Foster and colleagues elucidate the peptidoglycan architecture and insertion pattern in Escherichia coli and other Gram-negative bacteria, and propose a new model for cell wall elongation.