Regulation of polar peptidoglycan biosynthesis by Wag31 phosphorylation in mycobacteria.

Background: Sensing and responding to environmental changes is a central aspect of cell division regulation. Mycobacterium tuberculosis contains eleven Ser/Thr kinases, two of which, PknA and PknB, are key signaling molecules that regulate cell division/morphology. One substrate of these kinases is Wag31, and we previously showed that partial depletion of Wag31 caused morphological changes indicative of cell wall defects, and that the phosphorylation state of Wag31 affected cell growth in mycobacteria.

The effect of Wag31 phosphorylation on the cells and the cell envelope fraction of wild-type and conditional mutants of Mycobacterium smegmatis studied by visible-wavelength Raman spectroscopy.

Non-surface-enhanced Raman spectroscopy using a 514.5 nm wavelength laser has been used to measure the molecular difference of conditional mutants of Mycobacterium smegmatis expressing three different alleles: wild-type wag31(Mtb), phosphoablative wag31T73A(Mtb), and phosphomimetic wag31T73E(Mtb). This study demonstrates that the phosphorylation of Wag31, a key cell-division protein, causes significant differences in the quantity of amino acids associated with peptidoglycan precursor proteins and lipid II which are observable in the Raman spectra of these cells.