Catalytic domain of uncharacterized Mycobacterium tuberculosis Rv2075c-like proteins
This subfamily corresponds to the catalytic domain present in uncharacterized Mycobacterium tuberculosis Rv2075c and its homologs. Members in this family are more closely related to the Streptomyces antibioticus phosphatidylinositol-specific phospholipase C1(SaPLC1)-like proteins rather than the typical bacterial phosphatidylinositol-specific phospholipase C (PI-PLC, EC 126.96.36.199), which participate in Ca2+-independent PI metabolism, hydrolyzing the membrane lipid phosphatidylinositol (PI) to produce phosphorylated myo-inositol and diacylglycerol (DAG). In contrast, SaPLC1-like proteins have two Ca2+-chelating amino acid substitutions which convert them to metal-dependent bacterial PI-PLC. Rv2075c and its homologs have the same amino acid substitutions as well, which might suggest they have metal-dependent PI-PLC activity.
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 the structure evidence of catalytic site in Bacillus cereus phosphatidylinositol-specific phospholipase C.