Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparison was made between properties of a recently discovered Entamoeba histolytica lectin which has a carbohydrate specificity for N-acetylglucosamine oligosaccharides and the previously found toxin-like principle of the ameba. A separation between these two activities was achieved upon subcellular fractionation by high speed centrifugation of freeze-thawed disrupted E. histolytica trophozoites (strain HM-1). Practically all of this lectin activity, as determined by hemagglutination of glutaraldehyde-fixed human erythrocytes, was found associated with the sedimented membrane fraction. This fraction did not affect monolayers of tissue-cultured mammalian cells. On the other hand, the soluble supernatant solution caused extensive damage to the tissue-cultured cells (change in morphology and detachment of cells). Both the lectin and toxin activities were heat-labile and their activities were preserved by the presence of reducing agents and proteolytic enzyme inhibitors. In contrast to the toxin, the isolated lectin was inactive at pH 7.2 and active only at pH 5.7-6.0. Both the lectin and toxin were inhibited by a number of macromolecular compounds such as chitin, peptidoglycan, bovine serum and an IgA fraction isolated from human colostrum. Only the lectin activity, however, was inhibited by low molecular weight chitin oligosaccharides (GlcNAc)n=2-6 or by lysozyme-digested peptidoglycan subunits. Moreover, fetuin and a ganglioside mixture extracted from ox brain were found to inhibit only the toxin-like activity. The IgG fraction of sera from patients with invasive amebiasis neutralized both lectin and toxin-like activities, while IgG from normal sera failed to neutralize either activity. Although our results indicate that in E. histolytica, lectin and toxin are two separate activities, both of them share a considerable number of properties which does not exclude the possibility that they may be related.
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PMID:Lectin and toxin-like activities of Entamoeba histolytica: comparison of properties. 626 46

Entamoeba histolytica is a protozoan parasite that causes colitis and liver abscesses. Several Entamoeba species and strains with differing levels of virulence have been identified. E. histolytica HM-1:IMSS is a virulent strain, E. histolytica Rahman is a nonvirulent strain, and Entamoeba dispar is a nonvirulent species. We used an E. histolytica DNA microarray consisting of 2,110 genes to assess the transcriptional differences between these species/strains with the goal of identifying genes whose expression correlated with a virulence phenotype. We found 415 genes expressed at lower levels in E. dispar and 32 genes with lower expression in E. histolytica Rahman than in E. histolytica HM-1:IMSS. Overall, 29 genes had decreased expression in both the nonvirulent species/strains than the virulent E. histolytica HM-1:IMSS. Interestingly, a number of genes with potential roles in stress response and virulence had decreased expression in either one or both nonvirulent Entamoeba species/strains. These included genes encoding Fe hydrogenase (9.m00419), peroxiredoxin (176.m00112), type A flavoprotein (6.m00467), lysozyme (6.m00454), sphingomyelinase C (29.m00231), and a hypothetical protein with homology to both a Plasmodium sporozoite threonine-asparagine-rich protein (STARP) and a streptococcal hemagglutinin (238.m00054). The function of these genes in Entamoeba and their specific roles in parasite virulence need to be determined. We also found that a number of the non-long-terminal-repeat retrotransposons (EhLINEs and EhSINEs), which have been shown to modulate gene expression and genomic evolution, had lower expression in the nonvirulent species/strains than in E. histolytica HM-1:IMSS. Our results, identifying expression profiles and patterns indicative of a virulence phenotype, may be useful in characterizing the transcriptional framework of virulence.
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PMID:Identification of differentially expressed genes in virulent and nonvirulent Entamoeba species: potential implications for amebic pathogenesis. 1636 89