Catalytic domain of Bacillus cereus phosphatidylinositol-specific phospholipases C and similar proteins
This subfamily corresponds to the catalytic domain present in Bacillus cereus phosphatidylinositol-specific phospholipase C (PI-PLC, EC 22.214.171.124) and its sequence homologs found in bacteria and eukaryota. Bacterial PI-PLCs participate in Ca2+-independent PI metabolism, hydrolyzing the membrane lipid phosphatidylinositol (PI) to produce phosphorylated myo-inositol and diacylglycerol (DAG). Although their precise physiological function remains unclear, bacterial PI-PLCs may function as virulence factors in some pathogenic bacteria. Bacterial PI-PLCs contain a single TIM-barrel type catalytic domain. Their catalytic mechanism is based on general base and acid catalysis utilizing two well conserved histidines, and consists of two steps, a phosphotransfer and a phosphodiesterase reaction. This family also includes some uncharacterized eukaryotic homologs, which contains a single TIM-barrel type catalytic domain, X domain. They are similar to bacterial PI-PLCs, and distinct from typical eukaryotic PI-PLCs, which have a multidomain organization that consists of a PLC catalytic core domain, and various regulatory domains, and strictly require Ca2+ for their catalytic activities. The prototype of this family is Bacillus cereus PI-PLC, which has a moderate thermal stability and is active as a monomer.
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.
Structure:1GYM; Bacillus cereus phosphatidylinositol-specific phospholipase C catalytic site - View structure with Cn3D