Relating corynebacterial cell envelope layers to its biochemical and physical properties

The cell wall plays a central role in maintaining bacterial shape and structural stability. In the Corynebacteriaceae family, which includes Corynebacterium, Mycobacterium, Nocardia, and Rhodococcus, the envelope has a distinctive organization: peptidoglycan is covalently attached to arabinogalactan, which is subsequently enveloped by an outer layer of mycolic acids. In this study, we used Corynebacterium glutamicum as a model to examine how disruptions in different layers of the cell envelope, specifically the arabinogalactan and mycolic acid layers, influence both biochemical and biophysical properties. We assessed surface hydrophobicity, antibiotic sensitivity, and lipid composition, and complemented these assays with atomic force microscopy to examine structural changes. Our analysis of multiple cell wall mutants suggests that a division of labour occurs among the layers of the corynebacterial envelope, where each layer contributes to distinct, but complementary functions to overall cell wall physiology.