The identification of a phospholipase B precursor in human neutrophils

Abstract

A phospholipase B (PLB) precursor was purified from normal human granulocytes using Sephadex G‐75, Mono‐S cation‐exchange and hydroxyapatite columns. The molecular mass of the protein was estimated to be ∼ 130 kDa by gel filtration and 22 and 42 kDa by SDS/PAGE. Tryptic peptide and sequence analyses by MALDI‐TOF and tandem mass spectrometry (MS/MS) identified the protein as a FLJ22662 (Homo sapiens) gene product, a homologue of the amoeba Dictyostelium discoideum PLB. The native protein needed modifications to acquire deacylation activity against phospholipids including phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and lysophospholipids. Enzyme activity was associated with fragments derived from the 42 kDa fragment. The enzyme revealed a PLB nature by removing fatty acids from both the sn‐1 and sn‐2 positions of phospholipids. The enzyme is active at a broad pH range with an optimum of 7.4. Immunoblotting of neutrophil postnuclear supernatant using antibodies against the 42 kDa fragment detected a band at a molecular mass of 42 kDa, indicating a neutrophil origin of the novel PLB precursor. The existence of the PLB precursor in neutrophils and its enzymatic activity against phospholipids suggest a role in the defence against invading microorganisms and in the generation of lipid mediators of inflammation.

Tissue-Specific Expression and Regulatory Networks of Pig MicroRNAome

“…The subject of the second permissive module (Figure 7 B), (73 nodes and 110 edges) can be described as the transcription regulation in inflammatory cells. An interesting gene of this module is PLBD1 that codify for a phospholipase B precursor purified from normal granulocytes [70]. The expression of this gene appears to be connected in the module with 8 different miRNAs whose expression level is anti-correlated.…”

Glycerophosphocholine Utilization by Candida albicans

“…GroPCho is produced through the activity of deacylating phospholipases (Fig. 10C), such as those of the A 1 -, A 2 -, and B-type, that are widespread, having been found in bacteria (45,46), fungi (7), and humans (47). Thus, GroPCho is a common metabolite, and its presence has been noted in several locations relevant to C. albicans infection, including serum (11, 12, 14 -19), the gastrointestinal tract, and the urinary tract (11,17,19,20).…”

The glycerophosphoinositols: cellular metabolism and biological functions

“…More recently, a PLB precursor was isolated from the secretory organelles of human neutrophils that shows deacylation activity towards phospholipids, including phosphatidylcholine, PtdIns, phosphatidylethanolamine and their respective lysophospholipids [73]. Deacylation activity has also been detected in in vitro assays using a number of substrates, such as didecanoyl-phosphatidylcholine, dipalmitoyl-phosphatidylcholine, PtdIns, phosphatidylethanolamine and lysophosphatidylcholine, indicating that this PLB can act on a wide range of different membrane phospholipids.…”