Staphylococcus aureus Mutants Lacking the LytR-CpsA-Psr Family of Enzymes Release Cell Wall Teichoic Acids into the Extracellular Medium

Abstract

ABSTRACT 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 deposit WTA in the envelope, while Staphylococcus aureus Δ lcp mutants display impaired growth and reduced levels of envelope phosphate. We show here that the S. aureus Δ lcp mutant synthesized WTA yet released ribitol phosphate polymers into the extracellular medium. Further, Δ lcp mutant 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. aureus WTA synthesis genes ( tagB , tarF , or tarJ2 ) inhibit growth, which is attributed to the depletion of bactoprenol, an essential component of peptidoglycan synthesis (lipid II). The growth defect of S. aureus tagB and tarFJ mutants was alleviated by inhibition of WTA synthesis with tunicamycin, whereas the growth defect of the Δ lcp mutant was not relieved by tunicamycin treatment or by mutation of tagO , whose product catalyzes the first committed step of WTA synthesis. Further, sortase A-mediated anchoring of proteins to peptidoglycan, which also involves bactoprenol and lipid II, was not impaired in the Δ lcp mutant. We propose a model whereby the S. aureus Δ lcp mutant, defective in tethering WTA to the cell wall, cleaves WTA synthesis intermediates, releasing ribitol phosphate into the medium and recycling bactoprenol for peptidoglycan synthesis.