The β-N-acetylhexosaminidase of Entamoeba histolytica is composed of two homologous chains and has been localized to cytoplasmic granules

Riekenberg, Sabine; Flockenhaus, Bettina; Vahrmann, Anke; Müller, Mónika; Leippe, Matthias; Kieß, Michael; Scholze, Henning

doi:10.1016/j.molbiopara.2004.09.003

Cited by 22 publications

(14 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One is involved in the alteration of the structure of N-glycans generated in the cell, while the other plays in the chitin degradation processes. Although it has not been demonstrated how β-hexosaminidase is involved in the cytopathy of E. histolytica , it is conceivable that E. histolytica β-hexosaminidase degrades glycoconjugates of the extracellular matrix components to pass basement membranes, as previously suggested [53]. It was reported that lysozyme gene was poorly expressed in E. histolytica Rahman strain, which apparently lost virulence, and non-virulent E. dispar , compared to E. histolytica HM-1:IMSS strain [54], [55].…”

Section: Discussionmentioning

confidence: 88%

Novel Transmembrane Receptor Involved in Phagosome Transport of Lysozymes and β-Hexosaminidase in the Enteric Protozoan Entamoeba histolytica

2012

View full text Add to dashboard Cite

Lysozymes and hexosaminidases are ubiquitous hydrolases in bacteria and eukaryotes. In phagocytic lower eukaryotes and professional phagocytes from higher eukaryotes, they are involved in the degradation of ingested bacteria in phagosomes. In Entamoeba histolytica , which is the intestinal protozoan parasite that causes amoebiasis, phagocytosis plays a pivotal role in the nutrient acquisition and the evasion from the host defense systems. While the content of phagosomes and biochemical and physiological roles of the major phagosomal proteins have been established in E. histolytica , the mechanisms of trafficking of these phagosomal proteins, in general, remain largely unknown. In this study, we identified and characterized for the first time the putative receptor/carrier involved in the transport of the above-mentioned hydrolases to phagosomes. We have shown that the receptor, designated as cysteine protease binding protein family 8 (CPBF8), is localized in lysosomes and mediates transport of lysozymes and β-hexosaminidase α-subunit to phagosomes when the amoeba ingests mammalian cells or Gram-positive bacillus Clostridium perfringens . We have also shown that the binding of CPBF8 to the cargos is mediated by the serine-rich domain, more specifically three serine residues of the domain, which likely contains trifluoroacetic acid-sensitive O-phosphodiester-linked glycan modifications, of CPBF8. We further showed that the repression of CPBF8 by gene silencing reduced the lysozyme and β-hexosaminidase activity in phagosomes and delayed the degradation of C. perfringens . Repression of CPBF8 also resulted in decrease in the cytopathy against the mammalian cells, suggesting that CPBF8 may also be involved in, besides the degradation of ingested bacteria, the pathogenesis against the mammalian hosts. This work represents the first case of the identification of a transport receptor of hydrolytic enzymes responsible for the degradation of microorganisms in phagosomes.

show abstract

Section: Discussionmentioning

confidence: 88%

Novel Transmembrane Receptor Involved in Phagosome Transport of Lysozymes and β-Hexosaminidase in the Enteric Protozoan Entamoeba histolytica

2012

View full text Add to dashboard Cite

show abstract

“…Two β-N-acetylhexosaminidases have been identified, cloned and characterized. These enzymes are most probably involved in the destruction of glycoconjugates of the extracellular matrix components to pass basement membranes [32]. …”

Section: Introductionmentioning

confidence: 99%

Phylogenetic analyses suggest multiple changes of substrate specificity within the Glycosyl hydrolase 20 family

2008

View full text Add to dashboard Cite

BackgroundBeta-N-acetylhexosaminidases belonging to the glycosyl hydrolase 20 (GH20) family are involved in the removal of terminal β-glycosidacally linked N-acetylhexosamine residues. These enzymes, widely distributed in microorganisms, animals and plants, are involved in many important physiological and pathological processes, such as cell structural integrity, energy storage, pathogen defence, viral penetration, cellular signalling, fertilization, development of carcinomas, inflammatory events and lysosomal storage diseases. Nevertheless, only limited analyses of phylogenetic relationships between GH20 genes have been performed until now.ResultsCareful phylogenetic analyses of 233 inferred protein sequences from eukaryotes and prokaryotes reveal a complex history for the GH20 family. In bacteria, multiple gene duplications and lineage specific gene loss (and/or horizontal gene transfer) are required to explain the observed taxonomic distribution. The last common ancestor of extant eukaryotes is likely to have possessed at least one GH20 family member. At least one gene duplication before the divergence of animals, plants and fungi as well as other lineage specific duplication events have given rise to multiple paralogous subfamilies in eukaryotes. Phylogenetic analyses also suggest that a second, divergent subfamily of GH20 family genes present in animals derive from an independent prokaryotic source. Our data suggest multiple convergent changes of functional roles of GH20 family members in eukaryotes.ConclusionThis study represents the first detailed evolutionary analysis of the glycosyl hydrolase GH20 family. Mapping of data concerning physiological function of GH20 family members onto the phylogenetic tree reveals that apparently convergent and highly lineage specific changes in substrate specificity have occurred in multiple GH20 subfamilies.

show abstract

“…Previous studies have identified numerous glycosidase activities in E. histolytica lysates and secretory products. More specifically, the parasite has been found to produce a sialidase, an ␣-glucosidase, and ␤-N-acetylhexosaminidase, enzymes which are released by the parasite and are hypothesized to be involved in amebic pathogenesis (7,9,14). These glycosidases may play a role in disrupting mucin by exposing the protein backbone to parasite proteases.…”

mentioning

confidence: 99%

Entamoeba histolytica -Secreted Products Degrade Colonic Mucin Oligosaccharides

2005

View full text Add to dashboard Cite

Degradation of the mucus layer by Entamoeba histolytica is a prerequisite for invasion of the colonic mucosa. In this study, we demonstrate that amoeba-secreted products degrade 3 H-labeled and native colonic mucin oligosaccharides independently of proteolytic activity. We conclude that E. histolytica degrades mucin oligosaccharides, which may facilitate parasite invasion of the colon.Entamoeba histolytica is responsible for at least 50 million cases of diarrhea and an estimated 100,000 deaths per annum and ranks second only to malaria as a cause of mortality due to a protozoan parasite (12). Infection with the parasite leads to amebic colitis, colonic ulceration, and less frequently, dissemination to the liver, resulting in amebic liver abscess. The initial events leading to invasion of the colon by E. histolytica are poorly understood, and the mechanisms used by the parasite to overcome the innate host defenses of the gastrointestinal tract are currently under investigation. The parasite colonizes the colonic mucus layer by binding mucin oligosaccharides via a 170-kDa Gal/GalNAc lectin and must traverse this protective barrier in order to cause epithelial cell damage and colonic ulceration. Mucin oligosaccharides serve to protect the mucin core from proteases, preserving the integrity of the mucin polymer. Various O-linked glycan structures are attached to the apomucin via O-glycosidic linkage to serine and threonine residues, and these O-glycan branches contain N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), fucose, galactose, and sialic acid. The oligosaccharide component of gastrointestinal mucin has been reported to account for up to 90% of its dry weight, and the densely packed oligosaccharides are responsible for many intrinsic physical properties of the mucus gel, including hydration, gel-forming capacity, protease resistance, and rigidity (3). Previous studies have identified numerous glycosidase activities in E. histolytica lysates and secretory products. More specifically, the parasite has been found to produce a sialidase, an ␣-glucosidase, and ␤-N-acetylhexosaminidase, enzymes which are released by the parasite and are hypothesized to be involved in amebic pathogenesis (7,9,14). These glycosidases may play a role in disrupting mucin by exposing the protein backbone to parasite proteases. Previously, we have shown that E. histolytica-secreted cysteine proteases degrade the poorly glycosylated regions of MUC2, and we hypothesize that the parasite may use the concerted actions of glycosidases and proteases to disassemble the mucin polymeric network (5).In the present study, we determined whether E. histolyticasecreted glycosidases could degrade colonic mucin oligosaccharides. Parasite secretory products were collected from trophozoites incubated in Hanks' balanced salt solution for 2 h, and Ͼ95% of trophozoites were viable as determined by trypan blue exclusion assay (13). Secreted products were assayed for activity against a panel of glycosidase substrates as previously described with s...

show abstract

The β-N-acetylhexosaminidase of Entamoeba histolytica is composed of two homologous chains and has been localized to cytoplasmic granules

Cited by 22 publications

References 32 publications

Novel Transmembrane Receptor Involved in Phagosome Transport of Lysozymes and β-Hexosaminidase in the Enteric Protozoan Entamoeba histolytica

Novel Transmembrane Receptor Involved in Phagosome Transport of Lysozymes and β-Hexosaminidase in the Enteric Protozoan Entamoeba histolytica

Phylogenetic analyses suggest multiple changes of substrate specificity within the Glycosyl hydrolase 20 family

Entamoeba histolytica -Secreted Products Degrade Colonic Mucin Oligosaccharides

Contact Info

Product

Resources

About