The murein endopeptidase MepA regulated by MtrAB and MprAB participate in cell wall homeostasis

The complete genome of Corynebacterium glutamicum contain a gene encoding murein endopeptidase MepA which maintain cell wall homeostasis by regulating peptidoglycan biosynthesis. In this study, we investigate the physiological function, localization and regulator of MepA. The result shows that mepA overexpression lead to peptidoglycan degradation and the defects in cell division. MepA-EGFP was shown to localizes exclusively at the cell cell septum. In addition, mepA overexpression increased cell permeability and reduced the resistance of cells to isoniazid, an antibiotic used to treat Mycobacterium tuberculosis infection. Furthermore, transcription analysis showed that mepA affected cell division and membrane transport pathways, and was coordinately regulated by the two-component systems MtrAB and MprAB(CgtS/R2).