Fig. 7: Model of MprF and YpfP-LtaA activity in protein secretion.
From: The cell envelope of Staphylococcus aureus selectively controls the sorting of virulence factors
MprF synthesizes LPG on the cell membrane, conferring positive charge on the bacterial surface. YpfP-LtaA provides the membrane anchor for LTA, and are important in maintaining surface hydrophobicity (indicated by the roughened cell wall in the ypfP mutant). In the mprF and ypfP mutants, while the general protein secretion is functional, the secretion of selected proteins is hampered. Specifically, LukAB, Hel, and IsaB are stuck inside the cell envelope (the membrane-proximal compartment) in the mprF mutant. In the ypfP mutant, LukAB and Geh are accumulated on the cell surface, while ScaH is stored in the membrane-proximal compartment.
