Bacterial Phosphatidylinositol‐Specific Phospholipases C as Membrane‐Attacking Agents and Tools for Research on GPI‐Anchored Proteins

Abstract

Bacterial phosphatidylinositol‐specific phospholipases C have been shown not only to cause breakdown of phosphatidylinositol but also to release GPI‐anchored proteins from the plasma membranes of eucaryotes. Several enzymes in this group have been sequenced by cloning genomic DNA, and the enzymes of Bacillus cereus and Listeria monocytogenes were analyzed for their structures by X‐ray crystallography. In the active sites of enzymes from Bacillus genera and L. monocytogenes, the roles of component amino acid residues in catalysis have been mostly clarified. The enzyme of Bacillus thuringiensis exhibited cytotoxicity against some cultivated cells. The enzyme of L. monocytogenes was shown to contribute to listerial infection of epithelial cells and macrophages as a virulence factor cooperating with other factors such as listeriolysin O and phosphatidylcholine‐preferring phospholipase C. Recently, this enzyme proved to stimulate the signal‐transduction system of host cells in listeriosis. The requirements for effective utilization of bacterial phosphatidylinositol‐specific phospholipases C should be considered in research on GPI‐anchored proteins, cellular transduction, and so forth, given the unique properties of these enzymes.