Staphylococcus aureus mutants lacking the LytR-CpsA-Psr family of enzymes release cell wall teichoic acids into the extracellular medium

The LytR-CpsA-Psr (LCP) proteins are thought to transfer bactoprenol-linked biosynthetic intermediates of wall teichoic acid (WTA) to the peptidoglycan of Gram-positive bacteria. In Bacillus subtilis, mutants lacking all three LCP enzymes do not de-posit WTA in the envelope, while Staphylococcus aureuslcpmutants display impaired growth and reduced levels of envelope phosphate. We show here that the S. aureuslcpmutant synthesizedWTA yet released ribitol phosphate polymers into the ex-tracellular medium. Further,lcpmutant staphylococci no longer restricted the deposition of LysM-type murein hydrolases to cell division sites, which was associated with defects in cell shape and increased autolysis. Mutations in S. aureusWTA synthesis genes (tagB, tarF, or tarJ2) inhibit growth, which is attributed to the depletion of bactoprenol, an essential component of pepti-doglycan synthesis (lipid II). The growth defect of S. aureus tagB and tarFJmutants was alleviated by inhibition of WTA synthe-sis with tunicamycin, whereas the growth defect of thelcpmutant was not relieved by tunicamycin treatment or by mutation of tagO, whose product catalyzes the first committed step ofWTA synthesis. Further, sortase A-mediated anchoring of proteins to peptidoglycan, which also involves bactoprenol and lipid II, was not impaired in thelcpmutant. We propose a model whereby the S. aureuslcpmutant, defective in tetheringWTA to the cell wall, cleaves WTA synthesis intermediates, releasing ribitol phosphate into the medium and recycling bactoprenol for peptidoglycan synthesis. The peptidoglycan layer protects Gram-positive bacteria fromosmotic lysis and serves as a barrier against compounds toxic to the membrane (1). Peptidoglycan also functions as a scaffol