Phosphatidylglycerol as biosynthetic precursor for the poly(glycerol phosphate) backbone of bifidobacterial lipoteichoic acid.

Phosphatidylglycerol functions as donor of the sn-glycerol 1-phosphate units in the synthesis in vitro of the 1,2-phosphodiester-linked glycerol phosphate backbone of the lipoteichoic acids of Bifidobacterium bifidum subsp. pennsylvanicum. The incorporation was catalysed by a membrane-bound enzyme system. After addition of chloroform/methanol the product formed coprecipitated with protein. The material was phenol-extractable and was co-eluted with purified lipoteichoic acid on Sepharose 6B. The reaction was stimulated by Triton X-100, UDP-glucose and UDP-galactose, but Mg2+ ions had no effect. The apparent values for Km and Vmax. of the phosphatidylglycerol incorporation were 1.4 mM and 3.1 nmol/h per mg of membrane protein, respectively. Labelled UDP-glucose and UDP-galactose were not incorporated into the lipoteichoic acid fraction by the particulate membrane preparation.