Zinc-dependent phospholipase C

In molecular biology, zinc-dependent phospholipases C is a family of bacterial phospholipases C enzymes, some of which are also known as alpha toxins.

Zinc dependent phospholipase C
Alpha toxin of Clostridium showing the zinc dependent phospholipase domain in red and the PLAT domain in yellow
Identifiers
Symbol	Zn_dep_PLPC
Pfam	PF00882
InterPro	IPR001531
PROSITE	PDOC00357
SCOP2	1ah7 / SCOPe / SUPFAM
OPM superfamily	81
OPM protein	1olp
CDD	cd11009
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Bacillus cereus contains a monomeric phospholipase C EC 3.1.4.3 (PLC) of 245 amino-acid residues. Although PLC prefers to act on phosphatidylcholine, it also shows weak catalytic activity with sphingomyelin and phosphatidylinositol.^[1] Sequence studies have shown the protein to be similar both to alpha toxin from Clostridium perfringens and Clostridium bifermentans, a phospholipase C involved in haemolysis and cell rupture,^[2] and to lecithinase from Listeria monocytogenes, which aids cell-to-cell spread by breaking down the 2-membrane vacuoles that surround the bacterium during transfer.^[3]

Each of these proteins is a zinc-dependent enzyme, binding 3 zinc ions per molecule.^[4] The enzymes catalyse the conversion of phosphatidylcholine and water to 1,2-diacylglycerol and choline phosphate.^[1][2][4]

In Bacillus cereus, there are nine residues known to be involved in binding the zinc ions: 5 His, 2 Asp, 1 Glu and 1 Trp. These residues are all conserved in the Clostridium alpha-toxin.

Some examples of this enzyme contain a C-terminal sequence extension that contains a PLAT domain which is thought to be involved in membrane localisation.^[5][6]