Too many strictures on structure.

In a recent Opinion article in Trends in Microbiology, Dmitriev et al. proposed an alternative to the existing model of peptidoglycan structure, in which the cell wall is composed of chains that are perpendicular to the membrane (as opposed to horizontal) and form a scaffold interconnected by peptide branches. However, both this model and the classical model are based on underlying assumptions about pore sizes, composition and structural regularity that deserve careful consideration. Not only do the uncertainties surrounding these basic mechanical questions make it impossible to decide which model of peptidoglycan structure is correct, they also leave open the possibility that the real structure is an amalgam of these or other models that have yet to be described.