Cross-linked peptidoglycan mediates lysostaphin binding to the cell wall envelope of Staphylococcus aureus.
Staphylococcus simulans bv. staphylolyticus secretes lysostaphin, a bacteriocin that cleaves pentaglycine cross bridges in the cell wall of Staphylococcus aureus. The C-terminal cell wall-targeting domain (CWT) of lysostaphin is required for selective binding of this bacteriocin to S. aureus cells; however, the molecular target for this was unknown. We used purified green fluorescent protein fused to CWT (GFP-CWT) to reveal species-specific association of the reporter with staphylococci. GFP-CWT bound S. aureus cells as well as purified peptidoglycan sacculi. The addition of cross-linked murein, disaccharides linked to interconnected wall peptides, blocked GFP-CWT binding to staphylococci, whereas murein monomers or lysostaphin-solubilized cell wall fragments did not. S. aureus strain Newman variants lacking the capacity for synthesizing polysaccharide capsule (capFO), poly-N-acetylglucosamine (icaAC), lipoprotein (lgt), cell wall-anchored proteins (srtA), or the glycolipid anchor of lipoteichoic acid (ypfP) bound GFP-CWT similar to wild-type staphylococci. A tagO mutant strain, defective in the synthesis of polyribitol wall teichoic acid attached to the cell wall envelope, displayed increased GFP-CWT binding. In contrast, a femAB mutation, reducing both the amount and the length of peptidoglycan cross-linking (monoglycine cross bridges), showed a dramatic reduction in GFP-CWT binding. Thus, the CWT domain of lysostaphin directs the bacteriocin to cross-linked peptidoglycan, which also serves as the substrate for its glycyl-glycine endopeptidase domain.
Department of Microbiology, 920 E. 58th St., Chicago, IL 60637, USA.
Angelika
A
Gründling
Olaf
O
Schneewind
D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D003432:Cross-Linking Reagents; D008070:Lipopolysaccharides / Q000378:metabolism; D008248:Lysostaphin / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013211:Staphylococcus aureus / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D013682:Teichoic Acids / Q000378:metabolism
D003432:Cross-Linking Reagents; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D013682:Teichoic Acids; C009900:lipoteichoic acid; D008248:Lysostaphin