Biosynthesis of wall tiechoic acids in Staphylococcus aureus H, Micrococcus varians and Bacillus subtilis W23

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Abstract
The precursors for linkage unit (LU) synthesis in Staphylococcus aureus H were UDP‐GIcNAc, UDP‐N‐acetylmannosamine (ManNAc) and CDP‐glycerol and synthesis was stimulated by ATP. Moraprenol‐PP‐GlcNAc,‐ManNAc‐(glycerol phosphate)1–3 was formed from chemically synthesised moraprenol‐PP‐GlcNAc, UDP‐ManNAc and CDP‐glycerol in the presence of Triton X‐100. LU intermediates formed under both conditions served as acceptors for ribitol phosphate residues, from CDP‐ribitol, which comprise the main chain. The intial transfer of GlcNAc‐1‐phosphate from UDP‐GlcNAc was very sensitive to tunicamycin whereas the subsequent transfer of ManNAc from UDP‐ManNAc was not. Poly(GlcNAc‐1‐phosphate) and LU synthesis in Micrococcus varians, with endogenous lipid acceptor, UDP‐GlcNAc and CDP‐glycerol, was stimulated by UDP‐ManNAc. Synthesis of LU on exogenous moraprenol‐PP‐GlcNAc, with Triton X‐100, was dependent on UDP‐ManNAc and CDP‐glycerol and the intermediates formed served as substrates for polymer synthesis. Membranes from Bacillus subtilis W23 had much lower levels of LU synthesis, but UDP‐ManNAc was again required for optimal synthesis in the presence of UDP‐GlcNAc and CDP‐glycerol. Conditions for LU synthesis on exogenous moraprenol‐PP‐GlcNAc were not found in this organism. LU synthesis on endogenous acceptor in the absence of UDP‐ManNAc was explained by contamination of membranes with UDP‐GlcNAc 2‐epimerase. Under appropriate conditions, low levels of this enzyme were sufficient to convert UDP‐GlcNAc into a mixture of UDP‐Glc‐NAc and UDP‐ManNAc and account for LU synthesis. The results indicate the formation of prenol‐PP‐GlcNAc‐ManNac‐(glycerol phosphate)1–3 which is involved in the synthesis of wall teichoic acids in S. aureus H, M. varians and B. subtilis W23 and their attachment to peptidoglycan.