Protein scaffold involving MSMEG_1285 maintains cell wall organization and mediates penicillin sensitivity in mycobacteria

Protein–protein interactions are key in mycobacterial physiology, notably during the biosynthesis of the very peculiar mycobacterial cell wall. In this paper, we demonstrate that MSMEG_1285 interacts with PonA1, a bifunctional penicillin‐binding protein involved in peptidoglycan biosynthesis. Deletion of MSMEG_1285 enhances Mycobacterium smegmatis resistance to penicillin antibiotics, a phenotype that is exacerbated by the additional deletion of hbhA . This also led to a substantial decrease in the amounts of porins in the cell wall, which are necessary for the import of small and hydrophilic β‐lactams. Deletion of both MSMEG_1285 and hbhA provoked an over‐representation of several enzymes involved in peptidoglycan degradation. Thus, we propose that MSMEG_1285 is part of a protein scaffold, which also involves PonA1 and HbhA, and that it is responsible for the tight regulation of peptidoglycan hydrolysis. This study provides a better understanding of the mycobacterial physiology, which is an essential step for strengthening the action of drugs that specifically target peptidoglycan biosynthesis.