Biosynthesis of glucosyl monophosphoryl undecaprenol and its role in lipoteichoic acid biosynthesis

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Abstract
A glucophospholipid was detected in an incubation mixture containing UDP-glucose, MgCl2, ATP and a particulate enzyme prepared from Streptococcus sanguis. The synthesis of this lipid was inhibited strongly by UDP and moderately by UMP. The molar ratio of glucose to phosphate in the purified lipid was 1:1. Glucose and glucose 1-phosphate were released by mild alkaline hydrolysis of the glucophospholipid. The lipid produced by mild acid degradation of the purified lipid yielded a TLC profile similar to that of acid-treated undecaprenol. One of the minor components exhibited the same mobility as untreated undecaprenol. To characterize further the lipid moiety of the glucophospholipid, a polyisoprenol was purified from the neutral lipid of S. sanguis. The polyisoprenol was converted in the presence of ATP, UDP-glucose and the particulate enzyme into a lipid which exhibited the same TLC mobility as the glucophospholipid. The structure of the polyisoprenol was determined by NMR and mass spectrometry to be an undecaprenol with an internal cis-trans ratio of 7:2. These results indicate that he glucophospholipid is glucosyl monophosphoryl undecaprenol. The glucosyl moiety of the glucophospholipid was incorporated in the presence of the particulate enzyme into a macromolecule which was characterized as a lipoteichoic acid by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DEAE-cellulose column chromatography. Glucosyl monophosphoryl undecaprenol is apparently the direct glucosyl donor in the synthesis of lipoteichoic acid.