Identification and Characterization of Novel Phosphatidate Phosphatase Families in Arabidopsis

Abstract

Phosphatidate (PA) phosphatase (PAP) is the enzyme which yeilds diacylglycerol (DAG) by dephosphorylating phosphatidic acid (PA), an end-product of Kennedy pathway with which glycerolipid metabolism commonly shares. Although homologues for mammalian membrane-associated PAP were reported in Arabidopsis,there is no evidence as to the chloroplast-localized or soluble type of PAP despite their importance in lipid metabolism.
Here,we detected a novel type of membrane-associated PAP in cyanobacteria and its five homologues in Arabidopsis that were distinct from mammalian-type PAP. Results of analyses showed that three out of five were chloroplastic PAP. Meanwhile, recent identification of soluble PAP in Yeast (Han et al,2006) suggests two homologues in Arabidopsis. Therefore, Arabidopsis has at least two additional PAP families. Identification and characterization on these novel PAPs will be presented.