Catalytic domain of phosphatidylinositol-specific phospholipase C X domain containing and similar proteins
This family corresponds to the catalytic domain present in phosphatidylinositol-specific phospholipase C X domain containing proteins (PI-PLCXD) which are bacterial phosphatidylinositol-specific phospholipase C (PI-PLC, EC 184.108.40.206) sequence homologs mainly found in eukaryota. The typical eukaryotic phosphoinositide-specific phospholipase C (PI-PLC, EC 220.127.116.11) have a multidomain organization that consists of a PLC catalytic core domain, and various regulatory domains. The catalytic core domain is assembled from two highly conserved X- and Y-regions split by a divergent linker sequence. In contrast, eukaryotic PI-PLCXDs and their bacterial homologs contain a single TIM-barrel type catalytic domain, X domain, which is more closely related to that of bacterial PI-PLCs. Although the biological function of eukaryotic PI-PLCXDs still remains unclear, it may be distinct from that of typical eukaryotic PI-PLCs.
Comment:Both prokaryotic and eukaryotic PI-PLCs utilize a similar catalytic mechanism, a general base and acid catalysis involving two well conserved histidines. It consists of two steps, a phosphotransfer and a phosphodiesterase reaction.
Comment:Based on structure evidence of the catalytic site in Bacillus cereus phosphatidylinositol-specific phospholipase C.