ANCHOR STRUCTURE OF STAPHYLOCOCCAL SURFACE-PROTEINS II - COOH-TERMINAL STRUCTURE OF MURAMIDASE AND AMIDASE-SOLUBILIZED SURFACE PROTEIN

Surface proteins of the Gram-positive organism Staphylococcus aureus a re anchored to the bacterial cell wall by a transpeptidation mechanism during which the polypeptide is cleaved between the threonine (T) and the glycine (G) of the LPXTG motif. The carboxyl of threonine is subs equently amide linked to the amino of the pentaglycyl cross-bridge wit hin the staphylococcal peptidoglycan, Previous work examined the ancho r structure of surface proteins solubilized from the peptidoglycan by treatment with lysostaphin or phi 11 hydrolase and identified COOH-ter minally linked triglycyl or L-AZa-D-iGln-L-Lys(Gly(5))-D-Ala and MurNA c-[L-Ala-D-iGln-L-Lys(Gly(5))-D-Ala](beta 1-4)-GlcNAc, respectively, H ere, we report the anchor structure of surface proteins solubilized wi th N-acetylmuramidase and N-acetylmuramyI-L-alanine amidase. N-Acetylm uramidase-released surface protein was linked to MurNAc-[L-Ala-D-iGln- L-Lys(Gly(5))-D-Ala](beta 1-4)-GlcNAc, whereas N-acetylmuramyl-L-alani ne amidase treatment of the cell wall solubilized surface proteins lin ked to L-Ala-D-iGln-L-Lys(Gly(5))-D-Ala. Most, but not all, anchor str uctures were cross-linked to other cell wall subunits, in which the D- alanyl at position four was amide linked to the pentaglycyl of a neigh boring wall peptide.