The mycobacterial nucleoid-associated protein NapM exhibits stress-induced septal localization and modulates cell envelope gene expression

The bacterial chromosome is organized in a hierarchical and dynamic manner to facilitate various DNA transactions. Nucleoid-associated proteins (NAPs) are the most abundant small-scale chromosomal organizers, playing roles in maintaining chromosomal DNA integrity, gene regulation, DNA replication, and DNA repair. In this study, we characterize the recently identified mycobacterial NAP, NapM in Mycobacterium smegmatis . Our study shows that NapM exhibits a distinctive septal localization in response to stress affecting cell envelope integrity and modulates the expression of approximately one-third of M. smegmatis genes, including those involved in cell envelope biosynthesis. Our findings suggest that NapM regulates mycobacterial cell division under stress, enabling this saprophyte to adapt to constantly changing environmental conditions.