Phosphatidylglycerophosphate synthases from <i>Arabidopsis thaliana</i>

Abstract

Two Arabidopsis thaliana genes were shown to encode phosphatidylglycerophosphate synthases (PGPS) of 25.4 and 32.2 kDa, respectively. Apart from their N‐terminal regions, the two proteins 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 were 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.