Phosphatidylglyceroylalkylamine, a novel phosphoglycolipid precursor in Deinococcus radiodurans

We report here the structure of a previously uncharacterized phospholipid in the radiation-resistant bacterium Deinococcus radiodurans. This phospholipid, designated lipid 4, was shown by chemical analysis, HF hydrolysis, and nuclear magnetic resonance spectroscopy to be phosphatidylglyceroylalkylamine. Lipid 4 thus contains the unusual lipid constituents glyceric acid and alkylamines, which have previously been identified in two complex phosphoglycolipids from this organism. By [³²P]phosphate pulse-chase labeling techniques, lipid 4 was shown to be the precursor of the complex phosphoglycolipids α-galactosyl- and α-N-acetylglucosaminyl-phosphatidylglyceroylalkylamine. While phosphatidylglyceroylalkylamine is rapidly biosynthesized from P(i), its subsequent glycosylation occurs much more slowly. Therefore, we conclude that the final glycosylation step is the rate-limiting event in the biosynthesis of the complex phosphoglycolipids α-galactosyl- and α-N-acetylglucosaminyl-phosphatidylglyceroylalkylamine.