Disease relevance of plc

• A cellular deficiency of gangliosides causes hypersensitivity to Clostridium perfringens phospholipase C [1].
• The results showed that the plc mutants had demonstrably reduced virulence and therefore provided definitive genetic evidence for the essential role of alpha-toxin in gas gangrene or clostridial myonecrosis [2].
• However, when the 3.1-kb fragment was cloned into plasmid pUC19 and expressed in Escherichia coli, the plc genes from both type strains were similarly expressed and the toxins produced showed similar levels of activity [3].
• Such a difference in LD50 was also observed between Bacillus subtilis with and without the cloned plc gene [4].
• In developing Clostridium perfringens as a safe vaccine vector, the alpha toxin gene (plc) in the bacterial chromosome must be permanently inactivated [5].

High impact information on plc

• Alpha toxin-treated endothelial cells accumulated the products of the phospholipase C reaction, diacylglycerol and ceramide, and exhibited a decrease in the enzymatic precursors phosphatidylcholine and sphingomyelin [6].
• Alpha toxin from Clostridium perfringens type A, a phospholipase C, has been implicated in many of the localized and systemic features of gas gangrene [6].
• A gel retardation assay and hydroxyl radical footprinting revealed that the phased A-tracts facilitate the formation of the RNAP-plc promoter complex through extension of the contact region [7].
• Moreover, prolonged pretreatment of the cells with phorbol 12,13-dibutyrate, which leads to a marked decrease in the number of specific phorbol ester binding sites, prevents the phosphorylation of 80k stimulated by phorbol esters, phospholipase C, and platelet-derived growth factor [8].
• Phorbol esters, phospholipase C, and growth factors rapidly stimulate the phosphorylation of a Mr 80,000 protein in intact quiescent 3T3 cells [8].

Chemical compound and disease context of plc

• The possibility that this phosphorylation was related to activation of Ca2+ phospholipid-dependent protein kinase was suggested by the fact that phospholipid breakdown induced by exogenous treatment of the cells with Clostridium perfringens phospholipase C and 1-oleoyl-2-acetylglycerol also enhanced Mr 54,000 cellular protein phosphorylation [9].
• After a 3-h incubation of Krebs II ascitic cells in the presence of phospholipase C from Clostridium welchii under nonlytic conditions, the incorporation of [3H] choline into phosphatidylcholine was increased 1.7-fold as compared to untreated cells [10].
• Exposure of these two types of transfectant clones to C. perfringens PLC demonstrated that a cellular UDP-glucose deficiency causes hypersensitivity to the cytotoxic effect of this phospholipase [11].
• A reappraisal of the importance of phospholipase C hydrolysis products in the pathogenesis of cholesterol gallstones is warranted based on these observations [12].
• The effects of vasopressin on the total concentration of diacylglycerols and [14C]diacylglycerol were mimicked by an exogenous phospholipid phosphodiesterase (phospholipase C) from Clostridium perfringens [13].

Biological context of plc

• Another variable region spanning the major virulence gene plc, which encodes the cytolytic toxin, alpha, was located near oriC in all cases whereas the gene for another lethal typing toxin, epsilon, was borne by an episome [14].
• Comparison of the nucleotide sequence between the 3.1-kb fragments of the two type strains shows some differences both in the plc gene and in ORF2 [3].
• However, one of these proteins, which binds within the plc coding region, was not found in the type C strain, suggesting that it plays a role in the regulation of the plc gene expression [3].
• No significant difference in the nucleotide sequence of the plc promoter region was observed for any of the plc genes [15].
• The deduced amino acid sequence consists of 398 amino acid residues, coinciding with those of the plc genes previously determined [16].

Anatomical context of plc

• Human neutrophil peptide receptors: mobilization mediated by phospholipase C [17].
• The rate of incorporation of radiolabeled choline into lipids was increased 2-fold in phospholipase C-treated CHO cells as compared to untreated controls [18].
• Regulation of phosphatidylcholine biosynthesis in mammalian cells. I. Effects of phospholipase C treatment on phosphatidylcholine metabolism in Chinese hamster ovary cells and LM mouse fibroblasts [18].
• Activation of glucose transport in skeletal muscle by phospholipase C and phorbol ester. Evaluation of the regulatory roles of protein kinase C and calcium [19].
• Regulation of phosphatidylcholine biosynthesis in mammalian cells. II. Effects of phospholipase C treatment on the activity and subcellular distribution of CTP:phosphocholine cytidylyltransferase in Chinese hamster ovary and LM cell lines [20].

Associations of plc with chemical compounds

• The production of chloramphenicol acetyltransferase in C. perfringens was monitored during growth and the pattern of expression was shown to reflect levels of plc mRNA and alpha-toxin in the parent strain [21].
• However, neither phospholipase C nor 1-oleoyl-2-acetylglycerol enhanced attachment of P-29 cells or their lung-colonizing ability [9].
• Activities of choline kinase, choline phosphotransferase, glycerol-3-phosphate dehydrogenase, glycerol-3-phosphate acyltransferase, acylglycerol-3-phosphate acyltransferase, and phosphatidic acid phosphatase in phospholipase C-treated cells were the same or only slightly higher than in control cells [22].
• Levels of phosphocholine decreased and levels of CDP-choline increased in phospholipase C-treated cells, and a calculation of the disequilibrium ratio indicated that the cytidylyltransferase reaction was not at equilibrium [22].
• Further experiments with genetically engineered C. perfringens PLC variants showed that the sphingomyelinase activity and the C-domain are required for its cytotoxic effect in UDP-glucose-deficient cells [11].

Regulatory relationships of plc

• Mechanism of hepatic glycogen synthase inactivation induced by Ca2+-mobilizing hormones. Studies using phospholipase C and phorbol myristate acetate [23].

Other interactions of plc

• We found that the small 3'-portion of VR-RNA was sufficient for the activation of toxin genes, which suggested that VR-RNA itself could act as an RNA regulatory molecule for the plc and colA genes mediating the regulatory information from the VirR/VirS system in C. perfringens [24].
• The subsequent strain was complemented with separate plasmids that carried the alpha-toxin structural gene (plc), the perfringolysin O gene (pfoA), or both toxin genes, and the resultant isogenic strains were examined in a mouse myonecrosis model [25].
• In contrast, recombination was found to be a significant factor only for the virulence genes plc and colA and the housekeeping gene gyrA [26].
• Exogenous phospholipase C from Clostridium perfringens, at low concentrations, inactivated glycogen synthase and increased DAG without affecting cell Ca2+ or phosphorylase [23].

Analytical, diagnostic and therapeutic context of plc

• Northern blot analysis revealed that the type A strain produced 16 to 23 times more plc mRNA than the type C strain [3].
• Western blot analysis showed no production of alpha toxin protein in the culture supernatant of the plc mutant [5].
• Addition of an alphatoxin (plc) gene specific PCR as an in process control reaction was performed in order to prevent false negative PCR results [27].
• PCR analysis of 477 colonies of fecal spore isolates, from 159 patients who had a spore count > or = 10(3) cfu/g, gave positive plc gene detection in 436 colonies [28].
• Removal of phospholipase C from the cell cultures resulted in a return to basal levels of incorporation of [3H]choline into phosphatidylcholine, a decrease in the activity of cytidylyltransferase, and a loss of the membrane-bound form of the enzyme [20].

References