Role for a lytic polysaccharide monooxygenase in cell wall remodelling

Peptidoglycan is a major constituent of the bacterial cell wall and an important determinant for providing protection to cells. Besides peptidoglycan (PG), many bacteria synthesize other glycans that become part of the cell wall. Streptomycetes grow apically, where they synthesize a glycan that is exposed at the outer surface, but how it gets there is unknown. Here we show that deposition of the apical glycan at the cell surface depends on two key enzymes, the endoglucanase CslZ and the lytic polysaccharide monooxygenase LpmP. Activity of these enzymes allows localized remodeling and degradation of the PG, and we propose that this facilitates passage of the glycan. The absence of both enzymes not only prevents morphological development, but also sensitizes strains to lysozyme. Given that lytic polysaccharide monooxygenases are commonly found in microbes, this newly identified biological role in cell-wall remodelling may be widespread. ### Competing Interest Statement The authors have declared no competing interest.