Glycerophosphodiester phosphodiesterase domain of Saccharomyces cerevisiae YPL110cp and similar proteins
This subfamily corresponds to the glycerophosphodiester phosphodiesterase domain (GDPD) present in Saccharomyces cerevisiae YPL110cp and other uncharacterized fungal homologs. The product of S. cerevisiae ORF YPL110c (GDE1), YPL110cp (Gde1p), displays homology to bacterial and mammalian glycerophosphodiester phosphodiesterases (GP-GDE, EC 18.104.22.168), which catalyzes the degradation of glycerophosphodiesters to produce sn-glycerol-3-phosphate (G3P) and the corresponding alcohols. S. cerevisiae YPL110cp has been characterized as a cytoplasmic glycerophosphocholine (GPC)-specific phosphodiesterase that selectively hydrolyzes GPC, not glycerophosphoinositol (GPI), to generate choline and glycerolphosphate. YPL110cp has multi-domain architecture, including not only C-terminal GDPD, but also an SPX N-terminal domain along with several ankyrin repeats, which implies that YPL110cp may mediate protein-protein interactions in a variety of proteins and play a role in maintaining cellular phosphate levels. Members in this family are distantly related to S. cerevisiae YPL206cp, which selectively catalyzes the cleavage of phosphatidylglycerol (PG), not glycerophosphoinositol (GPI) or glycerophosphocholine (GPC), to diacylglycerol (DAG) and glycerophosphate, and has been characterized as a PG-specific phospholipase C.
Comment:The catalytic mechanism of glycerophosphodiester phosphodiesterases is based on the metal ion-dependent general acid-base reaction.
Comment:Based on structure evidence and site-directed mutagenesis of Thermoanaerobacter tengcongensis glycerophosphodiester phosphodiesterase, the catalytic site consists of two conserved histidine residues which serve as general acid and general base in catalyzing the hydrolysis of the 3'-5' phosphodiester bond.