Phosphatidylglycerophosphate synthases from Arabidopsis thaliana

Two Arabidopsis thaliana genes ere shown to encode phosphatidylglycerophosphate synthases (PGPS) of 25.4 and 32.2 kDa, respectively. Apart from their N-terminal regions, the two protein, exhibit high sequence similarity. Functional expression studies in yeast provided evidence that the 25.4 kDa protein is a microsomal PGPS while the 32.2 kDa protein represents a preprotein which can be imported into yeast mitochondria and processed to a mature PGPS. The two isozymes ere solubilized and purified as fusion proteins carrying a His tag at their C-terminus. Enzyme assays with both membrane fractions and purified enzyme fractions revealed that the two A. thaliana isozymes have similar properties but differ in their CDP-diacylglycerol species specificity. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.