Stereochemistry of reduction in digeranylgeranylglycerophospholipid reductase involved in the biosynthesis of archaeal membrane lipids from Thermoplasma acidophilum

The basic core structure of archaeal membrane lipids is 2,3-di-O-phytanylglyceryl phosphate, which is formed by reduction of 2,3-di-O-geranylgeranylglyceryl phosphate. This reaction is the final committed step in the biosynthesis of archaeal membrane lipids and is catalyzed by digeranylgeranylglycerophospholipid reductase (DGGGPL reductase). The putative DGGGPL reductase gene (Ta0516m) of Thermoplasma acidophilum was cloned and expressed. The purified recombinant enzyme appeared to catalyze the formation of 2,3-di-O-phytanylglyceryl phosphate from 2,3-di-O-geranylgeranylglyceryl phosphate, which confirmed that the Ta0516m gene of T. acidophilum encodes DGGGPL reductase. The stereospecificity in reduction of 2,3-di-O-phytylglyceryl phosphate by the recombinant reductase appeared to take place through addition of hydrogen in a syn manner by analyzing the enzyme reaction product by NMR spectroscopy.