Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Helminth parasites secrete extracellular vesicles (EVs) that can be internalised by host immune cells resulting in modulation of host immunity. While the molecular cargo of EVs have been characterised in many parasites, little is known about the surface-exposed molecules that participate in ligand-receptor interactions with the host cell surface to initiate vesicle docking and subsequent internalisation. Using a membrane-impermeable biotin reagent to capture proteins displayed on the outer membrane surface of two EV sub-populations (termed 15k and 120k EVs) released by adult F. hepatica, we describe 380 surface proteins including an array of virulence factors, membrane transport proteins and molecules involved in EV biogenesis/trafficking. Proteomics and immunohistochemical analysis show that the 120k EVs have an endosomal origin and may be released from the parasite via the protonephridial (excretory) system whilst the larger 15k EVs are released from the gastrodermal epithelial cells that line the fluke gut. A parallel lectin microarray strategy was used to profile the topology of major surface oligosaccharides of intact fluorogenically-labelled EVs as they would be displayed to the host. Lectin profiles corresponding to glycoconjugates exposed on the surface of the 15 K and 120K EV sub-populations are practically identical but are distinct from those of the parasite surface tegument, although all are predominated by high mannose sugars. We found that while the F. hepatica EVs were resistant to exo- and endo-glycosidases, the glyco-amidase PNGase F drastically remodelled the surface oligosaccharides and blocked the uptake of EVs by host macrophages. In contrast, pre-treatment with antibodies obtained from infected hosts, or purified antibodies raised against the extracellular domains of specific EV surface proteins (DM9-containing protein, CD63 receptor and myoferlin), significantly enhanced their cellular internalisation. This work highlights the diversity of EV biogenesis and trafficking pathways used by F. hepatica and sheds light on the molecular interaction between parasite EVs and host cells.
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PMID:Surface molecules of extracellular vesicles secreted by the helminth pathogen Fasciola hepatica direct their internalisation by host cells. 3065 64

In cells, asparagine/N-linked glycans are added to glycoproteins cotranslationally, in an attachment process that supports proper folding of the nascent polypeptide. We found that following pruning of N-glycan by the amidase PNGase F, the principal influenza vaccine antigen and major viral spike protein hemagglutinin (HA) spontaneously reattached N-glycan to its de-N-glycosylated positions when the amidase was removed from solution. This reaction, which we term N-glycanation, was confirmed by site-specific analysis of HA glycoforms by mass spectrometry prior to PNGase F exposure, during exposure to PNGase F, and after amidase removal. Iterative rounds of de-N-glycosylation followed by N-glycanation could be repeated at least three times and were observed for other viral glycoproteins/vaccine antigens, including the envelope glycoprotein (Env) from HIV. Covalent N-glycan reattachment was nonenzymatic as it occurred in the presence of metal ions that inhibit PNGase F activity. Rather, N-glycanation relied on a noncovalent assembly between protein and glycan, formed in the presence of the amidase, where linearization of the glycoprotein prevented this retention and subsequent N-glycanation. This reaction suggests that under certain experimental conditions, some glycoproteins can organize self-glycan addition, highlighting a remarkable self-assembly principle that may prove useful for re-engineering therapeutic glycoproteins such as influenza HA or HIV Env, where glycan sequence and structure can markedly affect bioactivity and vaccine efficacy.
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PMID:Spontaneous Glycan Reattachment Following N-Glycanase Treatment of Influenza and HIV Vaccine Antigens. 3191 36


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