Glycerophosphodiester phosphodiesterase domain of putative mammalian glycerophosphodiester phosphodiesterase GDE5 and similar proteins
This subfamily corresponds to the glycerophosphodiester phosphodiesterase domain (GDPD) present in putative mammalian GDE5 and similar proteins. Mammalian GDE5 is widely expressed in mammalian tissues, with highest expression in the spinal chord. Although its biological function remains unclear, mammalian GDE5 shows higher sequence homology to fungal and plant glycerophosphodiester phosphodiesterases (GP-GDEs, EC 22.214.171.124) than to other bacterial and mammalian GP-GDEs. It may also hydrolyze glycerophosphodiesters to sn-glycerol-3-phosphate (G3P) and the corresponding alcohols. In addition to C-terminal GDPD domain, all members in this subfamily have a starch binding domain (CBM20) in the N-terminus, which suggests these proteins may play a distinct role in glycerol metabolism.
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.