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John A. Gatehouse - One of the best experts on this subject based on the ideXlab platform.
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in vitro and in vivo binding of snowdrop Galanthus nivalis agglutinin gna and jackbean canavalia ensiformis con a lectins within tomato moth lacanobia oleracea larvae mechanisms of insecticidal action
Journal of Insect Physiology, 2001Co-Authors: Elaine Fitches, John P Edwards, Stephen D Woodhouse, John A. GatehouseAbstract:When fed in semi-artificial diet the lectins from snowdrop (Galanthus nivalis: GNA: mannose-specific) and jackbean (Canavalia ensiformis: Con A: specific for glucose and mannose) were shown to accumulate in vivo in the guts, malpighian tubules and haemolymph of Lacanobia oleracea (tomato moth) larvae. Con A, but not GNA, also accumulated in the fat bodies of lectin-fed larvae. The presence of glycoproteins which bind to both lectins in vitro was confirmed using labelled lectins to probe blots of polypeptides extracted from larval tissues. Immunolocalisation studies revealed a similar pattern of GNA and Con A binding along the digestive tract with binding concentrated in midgut sections. Binding of lectins to microvilli appeared to lead to transport of the proteins into cells of the gut and malpighian tubules. These results suggested that both lectins are able to exert systemic effects via transport from the gut contents to the haemolymph across the gut epithelium. The delivery of GNA and Con A to the haemolymph was shown to be dependent on their functional integrity by feeding larvae diets containing denatured lectins. Con A, but not GNA, was shown to persist in gut and fat body tissue of lectin-fed larvae chased with control diet for three days. Con A also shows more extensive binding to larval tissues in vitro than GNA, and these two factors are suggested to contribute to the higher levels of toxicity shown by Con A, relative to GNA, in previous long term bioassays.
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resistance to green leafhopper nephotettix virescens and brown planthopper nilaparvata lugens in transgenic rice expressing snowdrop lectin Galanthus nivalis agglutinin gna
Journal of Insect Physiology, 2000Co-Authors: Xavier Foissac, Paul Christou, Angharad M. R. Gatehouse, Nguyen Thi Loc, John A. GatehouseAbstract:Transgenic rice plants expressing snowdrop lectin (Galanthus nivalis agglutinin; GNA) were screened for resistance to green leafhopper (Nephotettix virescens; GLH), a major homopteran pest of rice. Survival was reduced by 29% and 53% (P,0.05) respectively, on plants where GNA expression was tissue-specific (phloem and epidermal layer) or constitutive. Similar levels of resistance in GNA-expressing transgenic rice were previously reported for rice brown planthopper (Nilaparvata lugens; BPH). GNA binding to glycoproteins in gut tissues showed that BPH contained more “receptors” than GLH, and that the binding affinity was stronger, particularly in the midgut. Subsequent toxicity of GNA is thus unlikely to be directly related to the amount of lectin bound. GNA was not detected in the honeydew of either insect species when they were fed on GNA-expressing plants, in contrast to results from artificial diet studies. This result suggests that GNA is not being delivered to the insect efficiently. When offered a free choice vs control plants, BPH nymphs tended to avoid plants expressing GNA; avoidance was less pronounced and took longer to develop on plants where GNA expression was tissue-specific, In contrast to BPH, GLH nymphs were attracted to plants expressing GNA, whether constitutively or in a tissue-specific manner. © 2000 Elsevier Science Ltd. All rights reserved.
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functional phytohemagglutinin pha and Galanthus nivalis agglutinin gna expressed in pichia pastoris correct n terminal processing and secretion of heterologous proteins expressed using the pha e signal peptide
FEBS Journal, 1999Co-Authors: Romaan J.m. Raemaekers, John A. Gatehouse, Laura De Muro, Anthony P FordhamskeltonAbstract:Phytohemagglutinin (Phaseolus vulgaris agglutinin; PHA; E- and L-forms) and snowdrop lectin (Galanthus nivalis agglutinin; GNA) were expressed in Pichia pastoris using native signal peptides, or the Saccharomycesα-factor preprosequence, to direct proteins into the secretory pathway. PHA and GNA were present as soluble, functional proteins in culture supernatants when expressed from constructs containing the α-factor preprosequence. The recombinant lectins, purified by affinity chromatography, agglutinated rabbit erythrocytes at concentrations similar to the respective native lectins. However, incomplete processing of the signal sequence resulted in PHA-E, PHA-L and GNA with heterogenous N-termini, with the majority of the protein containing N-terminal extensions derived from the α-factor prosequence. Polypeptides in which most of the α-factor prosequence was present were also glycosylated. Inclusion of Glu-Ala repeats at the C-terminal end of the α-factor preprosequence led to efficient processing N-terminal to the Glu-Ala sequence, but inefficient removal of the repeats themselves, resulting in polypeptides with heterogenous N-termini still containing N-terminal extensions. In contrast, PHA expressed with the native signal peptide was secreted, correctly processed, and also fully functional. No expression of GNA from a construct containing the native GNA signal peptide was observed. The PHA-E signal peptide directed correct processing and secretion of both GNA and green fluorescent protein (GFP) when used in expression constructs, and is suggested to have general utility for synthesis of correctly processed proteins in Pichia.
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Expression of the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA) in transgenic wheat plants: effects on predation by the grain aphid Sitobion avenae
Molecular Breeding, 1999Co-Authors: Eva Stoger, Sarah Williams, Paul Christou, Rachel E. Down, John A. GatehouseAbstract:Transgenic wheat plants containing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin; GNA) under the control of constitutive and phloem-specific promoters were generated through the particle bombardment method. Thirty-two independently derived plants were subjected to molecular and biochemical analyses. Transgene integration varied from one to twelve estimated copies per haploid genome, and levels of GNA expression from 0 to ca. 0.2% of total soluble protein were observed in different transgenic plants. Seven transgenic plants were selected for further study. Progeny plants from these parental transformants were selected for transgene expression, and tested for enhanced resistance to the grain aphid (Sitobion avenae) by exposing the plants to nymphal insects under glasshouse conditions. Bioassay results show that transgenic wheat plants from lines expressing GNA at levels greater than ca. 0.04% of total soluble protein decrease the fecundity, but not the survival, of grain aphids. We propose that transgenic approaches using insecticidal genes such as gna in combination with integrated pest management present promising opportunities for the control of damaging wheat pests.
Els J. M. Van Damme - One of the best experts on this subject based on the ideXlab platform.
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accelerated delivery of dsrna in lepidopteran midgut cells by a Galanthus nivalis lectin gna dsrna binding domain fusion protein
Pesticide Biochemistry and Physiology, 2021Co-Authors: Zarel Martinez Reyna, Els J. M. Van Damme, Kristof De Schutter, Elise Vogel, Niels Wynant, Jozef Vanden Broeck, Olivier Christiaens, Guy SmaggheAbstract:Abstract Lepidopteran insects are highly refractory to oral RNA interference (RNAi). Degradation, impaired cellular uptake and intracellular transport of double-stranded RNA (dsRNA) are considered the major factors responsible for the reduced RNAi efficiency in these insects. In this study, the potential of lectins to improve dsRNA delivery and RNAi efficacy was evaluated. First, a fusion protein consisting of the Galanthus nivalis agglutinin (GNA) and a dsRNA binding domain was developed, further referred to as GNA:dsRBD (GNAF). Then, its ability to increase dsRNA uptake and transfection efficiency in lepidopteran midgut cells was evaluated, as well as its ability to protect and promote the RNAi response in the beet armyworm Spodoptera exigua. Confocal microscopy analysis showed that GNAF-complexed dsRNA was internalized faster in Choristoneura fumiferana midgut CF1 cells (1 min) compared to naked dsRNA (>1 h). The faster uptake was also correlated with an increased RNAi efficiency in these CF1 cells. In vivo feeding bioassays with GNAF-complexed dsRNA led to an increased mortality in S. exigua compared to the controls. By targeting the essential gene V-ATPase A, we observed that the mortality increased to 48% in the GNAF-dsRNA treatment compared to only 8.3% and 6.6% in the control treatments with the naked dsRNA and the GNAF, respectively.
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Purification of GNA-Related Lectins from Natural Sources.
Methods in molecular biology (Clifton N.J.), 2020Co-Authors: Els J. M. Van DammeAbstract:The Galanthus nivalis lectin, abbreviated as GNA, is the model protein for a large group of mannose-binding lectins. Here, we describe the purification of GNA starting from dry bulbs. Using a combination of ion exchange chromatography and affinity chromatography on mannose-Sepharose, a highly pure preparation of GNA can be obtained.
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Differences in the mannose oligomer specificities of the closely related lectins from Galanthus nivalis and Zea mays strongly determine their eventual anti-HIV activity
Retrovirology, 2011Co-Authors: Bart Hoorelbeke, Dominique Schols, Els J. M. Van Damme, Pierre Rougé, Kristel Van Laethem, Elke Fouquaert, Jan BalzariniAbstract:Background In a recent report, the carbohydrate-binding specificities of the plant lectins Galanthus nivalis (GNA) and the closely related lectin from Zea mays (GNAmaize) were determined by glycan array analysis and indicated that GNAmaize recognizes complex-type N-glycans whereas GNA has specificity towards high-mannose-type glycans. Both lectins are tetrameric proteins sharing 64% sequence similarity.
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Identical homologs of the Galanthus nivalis agglutinin in Zea mays and Fusarium verticillioides
Plant Physiology and Biochemistry, 2010Co-Authors: Elke Fouquaert, Willy J Peumans, Godelieve Gheysen, Els J. M. Van DammeAbstract:The structural domain corresponding to the Galanthus nivalis agglutinin (GNA) is a mannose-binding motif that was originally discovered in plants but according to recent data also occurs in other eukaryotes and prokaryotes. Transcriptome analyses revealed that Fusarium verticillioides expresses a protein (FvGLLc1) identical to a recently identified cytoplasmic/nuclear GNA-like lectin from maize (ZmGLLc). The FvGLLc1 and ZmGLLc gene sequences are nearly identical in the coding region as well as in the intron and the 5 and 3 prime untranslated regions. However, whereas the Fusarium genome contains only a single gene with an intron, both an intronless and an intron containing lectin gene can be amplified from maize DNA. Southern blot analysis confirmed the presence of this cytoplasmic GNA-like gene in the maize and rice genome. A comparative analysis of the products amplified by different PCRs using genomic DNA from Fusarium species and maize DNA samples from sterile as well as contaminated plant material strongly indicated that the GNA-like sequence found in maize grown under sterile conditions is not derived from a contaminating Fusarium species. Furthermore, using a PCR-based approach it could be demonstrated that this particular type of lectin occurs also in other plants from distant taxa and is markedly conserved.
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Localization and Topogenesis Studies of Cytoplasmic and Vacuolar Homologs of the Galanthus nivalis Agglutinin
Plant and Cell Physiology, 2007Co-Authors: Elke Fouquaert, Willy J Peumans, Sally L. Hanton, Federica Brandizzi, Els J. M. Van DammeAbstract:The Galanthus nivalis agglutinin (GNA) is synthesized as a preproprotein. To corroborate the role of the different targeting peptides in the topogenesis of GNA and related proteins, different constructs were made whereby both the complete original GNA gene and different truncated sequences were coupled to the enhanced green fluorescent protein (EGFP). In addition, a GNA ortholog from rice that lacks the signal peptide and C-terminal propeptide sequence was fused to EGFP. These fusion constructs were expressed in tobacco BY-2 cells and their localization analyzed by confocal fluorescence microscopy. We observed that the processed preproprotein of GNA was directed towards the vacuolar compartment, whereas both the truncated forms of GNA corresponding to the mature lectin polypeptide and the rice ortholog of GNA were located in the nucleus and the cytoplasm. It can be concluded, therefore, that removal of the C-terminal propeptide and the signal peptide is sufficient to change the subcellular targeting of a normally vacuolar protein to the nuclear/cytoplasmic compartment of the BY-2 cells. These findings support the proposed hypothesis that cytoplasmic/nuclear GNA-like proteins and their vacuolar homologs are evolutionarily related and that the classical GNA-related lectins might have evolved from cytoplasmic orthologs through an evolutionary event involving the insertion of a signal peptide and a C-terminal propeptide.
Arpad Pusztai - One of the best experts on this subject based on the ideXlab platform.
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Modulation of Salmonella infection by the lectins of Canavalia ensiformis (Con A) and Galanthus nivalis (GNA) in a rat model in vivo.
Journal of Applied Microbiology, 2000Co-Authors: Patrick Naughton, Susan Bardocz, George Grant, Arpad PusztaiAbstract:The plant lectins, Concanavalin A (Con A) and Galanthus nivalis agglutinin (GNA) have been prefed to rats for 3 d pre- and 6 d postinfection with Salmonella typhimurium S986 or Salm. enteritidis 857. Con A significantly increased numbers of Salm. typhimurium S986 in the large intestine and in faeces, and severely impaired growth of the rats, more severely than is the case of infection with Salmonella typhimurium alone. Con A had much less effect on rats infected with Salm. enteritidis 857 only showing a significant increase in numbers in the colon, accompanied by intermittent increases of Salmonella in the faeces during the study. GNA significantly reduced pathogen numbers in the lower part of the small bowel and the large intestine of rats infected with Salm. typhimurium S986 and significantly improved rat growth. GNA had little effect on infection by Salm. enteritidis 857 with slight decreases in Salmonella numbers in the small intestine and large intestine and transient increases in the faeces.
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effect of diets containing genetically modified potatoes expressing Galanthus nivalis lectin on rat small intestine
The Lancet, 1999Co-Authors: Stanley W B Ewen, Arpad PusztaiAbstract:Summary Diets containing genetically modified (GM) potatoes expressing the lectin Galanthus nivalis agglutinin (GNA) had variable effects on different parts of the rat gastrointestinal tract. Some effects, such as the proliferation of the gastric mucosa, were mainly due to the expression of the GNA transgene. However, other parts of the construct or the genetic transformation (or both) could also have contributed to the overall biological effects of the GNA-GM potatoes, particularly on the small intestine and caecum.
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Effect of the insecticidal Galanthus nivalis agglutinin on metabolism and the activities of brush border enzymes in the rat small intestine
Journal of Nutritional Biochemistry, 1996Co-Authors: Arpad Pusztai, J. F. J. G. Koninkx, Henno G.c.j.m. Hendriks, Wouter Kok, Saskia Hulscher, Els J. M. Van Damme, George Grant, Susan BardoczAbstract:Abstract With increasing use of lectin genes in crop plants to improve insect resistance, the dietary exposure of humans to lectins will rise and it is necessary to assess whether the presently most favored insecticidal lectin, Galanthus nivalis agglutinin, would be harmful for mammals. Effects of Galanthus nivalis agglutinin on gut and brush border enzymes were studied in rats over a 10-day dietary exposure and compared with those of a known antinutrient, phytohaemagglutinin. At a level that provides insecticidal protection for plants but did not reduce the growth of young rats, Galanthus nivalis agglutinin had negligible effects on the weight and length of the small intestine even though there was a slight, but significant hypertrophy of this tissue. However, the activities of brush border enzymes were affected; sucrase-isomaltase activity was nearly halved and those of alkaline phosphatase and aminopeptidase were significantly increased. Although most of the changes in gut metabolism caused by the incorporation of Galanthus nivalis agglutinin in the diet were less extensive than those found with toxic phytohaemagglutinin, some of them may be potentially deleterious. Thus, further and longer animal studies are needed to establish whether it is safe to use Galanthus nivalis agglutinin in transgenic plants destined for human consumption.
Angharad M. R. Gatehouse - One of the best experts on this subject based on the ideXlab platform.
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the snowdrop lectin Galanthus nivalis agglutinin gna and a fusion protein butait gna have a differential affect on a pest noctuid lacanobia oleracea and the ectoparasitoid eulophus pennicornis
Physiological Entomology, 2010Co-Authors: M E Wakefield, Elaine Fitches, Howard A. Bell, Angharad M. R. GatehouseAbstract:Fusion proteins have considerable potential as novel insect control agents because they enable the oral delivery of insecticidal peptides to the haemolymph of pests. Transport is achieved via fusion of the toxin to a carrier protein Galanthus nivalis agglutinin (GNA) that, after ingestion, binds to and crosses the insect gut epithelia. A fusion protein comprising a toxin from the South Indian red scorpion (Mesobuthus tamulus) that is fused to a GNA polypeptide (ButaIT/GNA) has a detrimental effect on the development of tomato moth Lacanobia oleracea (L.) (Lepidoptera: Noctuidae) larvae. The present study examines the effects of ButaIT/GNA and GNA, delivered orally or by injection, on the development of L. oleracea larvae, and the subsequent effects on the gregarious ectoparasitoid Eulophus pennicornis (Nees) (Hymenoptera: Eulophidae) developing on ButaIT/GNA- and GNA-treated hosts. The fusion protein, but not GNA, reduces the growth of fifth stadium L. oleracea larvae. The development of E. pennicornis is not affected by the presence of ButaIT/GNA in hosts that ingest the protein, although it is affected when hosts are injected with the protein. This difference is considered to be a result of higher levels of fusion protein being present when the fusion protein is injected. Intact ButaIT/GNA is detected by immunoassay in the haemolymph of L. oleracea larvae after ingestion of the fusion protein. More unexpectedly, negative effects are observed for the growth of E. pennicornis larvae developing on hosts that have either ingested, or been injected with GNA.
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The snowdrop lectin Galanthus nivalis agglutinin (GNA) and a fusion protein ButaIT/GNA have a differential affect on a pest noctuid Lacanobia oleracea and the ectoparasitoid Eulophus pennicornis
Physiological Entomology, 2010Co-Authors: M E Wakefield, Elaine Fitches, Howard A. Bell, Angharad M. R. GatehouseAbstract:Fusion proteins have considerable potential as novel insect control agents because they enable the oral delivery of insecticidal peptides to the haemolymph of pests. Transport is achieved via fusion of the toxin to a carrier protein Galanthus nivalis agglutinin (GNA) that, after ingestion, binds to and crosses the insect gut epithelia. A fusion protein comprising a toxin from the South Indian red scorpion (Mesobuthus tamulus) that is fused to a GNA polypeptide (ButaIT/GNA) has a detrimental effect on the development of tomato moth Lacanobia oleracea (L.) (Lepidoptera: Noctuidae) larvae. The present study examines the effects of ButaIT/GNA and GNA, delivered orally or by injection, on the development of L. oleracea larvae, and the subsequent effects on the gregarious ectoparasitoid Eulophus pennicornis (Nees) (Hymenoptera: Eulophidae) developing on ButaIT/GNA- and GNA-treated hosts. The fusion protein, but not GNA, reduces the growth of fifth stadium L. oleracea larvae. The development of E. pennicornis is not affected by the presence of ButaIT/GNA in hosts that ingest the protein, although it is affected when hosts are injected with the protein. This difference is considered to be a result of higher levels of fusion protein being present when the fusion protein is injected. Intact ButaIT/GNA is detected by immunoassay in the haemolymph of L. oleracea larvae after ingestion of the fusion protein. More unexpectedly, negative effects are observed for the growth of E. pennicornis larvae developing on hosts that have either ingested, or been injected with GNA.
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effects of Galanthus nivalis agglutinin gna expressed in tomato leaves on larvae of the tomato moth lacanobia oleracea lepidoptera noctuidae and the effect of gna on the development of the endoparasitoid meteorus gyrator hymenoptera braconidae
Bulletin of Entomological Research, 2006Co-Authors: M E Wakefield, Elaine Fitches, John P Edwards, Howard A. Bell, Angharad M. R. GatehouseAbstract:The effect of ingestion of transgenic tomato leaves expressing the plant lectin Galanthus nivalis agglutinin (GNA) on development of larvae of Lacanobia oleracea (Linnaeus) was studied under laboratory conditions. When L. oleracea larvae were fed on tomato line 14.1H, expressing approximately 2.0% GNA, significant increases in the mean larval weight and in the amount of food consumed were found. This resulted in an overall reduction in the mean development time to the pupal stage of approximately 7 days. A significant increase in the percentage survival to the adult moth was also recorded when newly hatched larvae were reared on transgenic tomato leaves (72%) compared to larvae reared on untransformed leaves (40%). The effects of ingestion of GNA by L. oleracea larvae, via artificial diet or the leaves of transgenic tomato or potato plants, on the subsequent development of its solitary endoparasitoid Meteorus gyrator (Thunberg) was also studied. No significant effects on the life cycle parameters of M. gyrator developing in L. oleracea fed on GNA-containing diets were observed. Experiments with transgenic potato plants indicated that the stadium of the host larvae at parasitism had a greater influence on M. gyrator development than the presence of GNA. Potential GNA-binding glycoproteins were detected in the gut and body tissues of larval M. gyrator. Despite detection in host tissues, GNA could not be detected in adult M. gyrator and therefore it is likely that at the time of pupation M. gyrator are able to void the GNA in the meconial pellet.
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Large-scale production and purification of recombinant Galanthus nivalis agglutinin (GNA) expressed in the methylotrophic yeast Pichia pastoris
Biotechnology Letters, 2003Co-Authors: Philippe Baumgartner, Karen Harper, Romaan J.m. Raemaekers, Alain Durieux, Angharad M. R. Gatehouse, Howard V. Davies, Mark A. TaylorAbstract:The gene coding for agglutinin from Galanthus nivalis (GNA) was expressed in, and secreted by, the methylotrophic yeast, Pichia pastoris. Transformants of P. pastoris were selected and a process to produce and purify gram quantities of recombinant GNA was developed. GNA was secreted at approximately 80 mg l−1 at the 200 l scale and was purified to 95% homogeneity using hydrophobic interaction chromatography. The recombinant protein was similar to the protein synthesised in plant with respect to structure and biological activity.
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resistance to green leafhopper nephotettix virescens and brown planthopper nilaparvata lugens in transgenic rice expressing snowdrop lectin Galanthus nivalis agglutinin gna
Journal of Insect Physiology, 2000Co-Authors: Xavier Foissac, Paul Christou, Angharad M. R. Gatehouse, Nguyen Thi Loc, John A. GatehouseAbstract:Transgenic rice plants expressing snowdrop lectin (Galanthus nivalis agglutinin; GNA) were screened for resistance to green leafhopper (Nephotettix virescens; GLH), a major homopteran pest of rice. Survival was reduced by 29% and 53% (P,0.05) respectively, on plants where GNA expression was tissue-specific (phloem and epidermal layer) or constitutive. Similar levels of resistance in GNA-expressing transgenic rice were previously reported for rice brown planthopper (Nilaparvata lugens; BPH). GNA binding to glycoproteins in gut tissues showed that BPH contained more “receptors” than GLH, and that the binding affinity was stronger, particularly in the midgut. Subsequent toxicity of GNA is thus unlikely to be directly related to the amount of lectin bound. GNA was not detected in the honeydew of either insect species when they were fed on GNA-expressing plants, in contrast to results from artificial diet studies. This result suggests that GNA is not being delivered to the insect efficiently. When offered a free choice vs control plants, BPH nymphs tended to avoid plants expressing GNA; avoidance was less pronounced and took longer to develop on plants where GNA expression was tissue-specific, In contrast to BPH, GLH nymphs were attracted to plants expressing GNA, whether constitutively or in a tissue-specific manner. © 2000 Elsevier Science Ltd. All rights reserved.
Willy J Peumans - One of the best experts on this subject based on the ideXlab platform.
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Identical homologs of the Galanthus nivalis agglutinin in Zea mays and Fusarium verticillioides
Plant Physiology and Biochemistry, 2010Co-Authors: Elke Fouquaert, Willy J Peumans, Godelieve Gheysen, Els J. M. Van DammeAbstract:The structural domain corresponding to the Galanthus nivalis agglutinin (GNA) is a mannose-binding motif that was originally discovered in plants but according to recent data also occurs in other eukaryotes and prokaryotes. Transcriptome analyses revealed that Fusarium verticillioides expresses a protein (FvGLLc1) identical to a recently identified cytoplasmic/nuclear GNA-like lectin from maize (ZmGLLc). The FvGLLc1 and ZmGLLc gene sequences are nearly identical in the coding region as well as in the intron and the 5 and 3 prime untranslated regions. However, whereas the Fusarium genome contains only a single gene with an intron, both an intronless and an intron containing lectin gene can be amplified from maize DNA. Southern blot analysis confirmed the presence of this cytoplasmic GNA-like gene in the maize and rice genome. A comparative analysis of the products amplified by different PCRs using genomic DNA from Fusarium species and maize DNA samples from sterile as well as contaminated plant material strongly indicated that the GNA-like sequence found in maize grown under sterile conditions is not derived from a contaminating Fusarium species. Furthermore, using a PCR-based approach it could be demonstrated that this particular type of lectin occurs also in other plants from distant taxa and is markedly conserved.
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Localization and Topogenesis Studies of Cytoplasmic and Vacuolar Homologs of the Galanthus nivalis Agglutinin
Plant and Cell Physiology, 2007Co-Authors: Elke Fouquaert, Willy J Peumans, Sally L. Hanton, Federica Brandizzi, Els J. M. Van DammeAbstract:The Galanthus nivalis agglutinin (GNA) is synthesized as a preproprotein. To corroborate the role of the different targeting peptides in the topogenesis of GNA and related proteins, different constructs were made whereby both the complete original GNA gene and different truncated sequences were coupled to the enhanced green fluorescent protein (EGFP). In addition, a GNA ortholog from rice that lacks the signal peptide and C-terminal propeptide sequence was fused to EGFP. These fusion constructs were expressed in tobacco BY-2 cells and their localization analyzed by confocal fluorescence microscopy. We observed that the processed preproprotein of GNA was directed towards the vacuolar compartment, whereas both the truncated forms of GNA corresponding to the mature lectin polypeptide and the rice ortholog of GNA were located in the nucleus and the cytoplasm. It can be concluded, therefore, that removal of the C-terminal propeptide and the signal peptide is sufficient to change the subcellular targeting of a normally vacuolar protein to the nuclear/cytoplasmic compartment of the BY-2 cells. These findings support the proposed hypothesis that cytoplasmic/nuclear GNA-like proteins and their vacuolar homologs are evolutionarily related and that the classical GNA-related lectins might have evolved from cytoplasmic orthologs through an evolutionary event involving the insertion of a signal peptide and a C-terminal propeptide.
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marked depletion of glycosylation sites in hiv 1 gp120 under selection pressure by the mannose specific plant lectins of hippeastrum hybrid and Galanthus nivalis
Molecular Pharmacology, 2005Co-Authors: Jan Balzarini, Anders Bolmstedt, Sigrid Hatse, Els J. M. Van Damme, Willy J Peumans, Matheus Froeyen, Kristel Van Laethem, Dominique ScholsAbstract:The plant lectins from Hippeastrum hybrid (HHA) and Galanthus nivalis (GNA) are 50,000-D tetramers showing specificity for α-(1,3) and/or α-(1,6)-mannose oligomers. They inhibit HIV-1 infection at a 50% effective concentration of 0.2 to 0.3 μg/ml. Escalating HHA or GNA concentrations (up to 500 μg/ml) led to the isolation of three HIV-1(IIIB) strains in CEM T cell cultures that were highly resistant to HHA and GNA, several other related mannose-specific plant lectins, and the monoclonal antibody 2G12, modestly resistant to the mannose-specific cyanovirin, which is derived from a blue-green alga, but fully susceptible to other HIV entry inhibitors as well as HIV reverse transcriptase inhibitors. These mutant virus strains were devoid of up to seven or eight of 22 glycosylation sites in the viral envelope glycoprotein gp120 because of mutations at the Asn or Thr/Ser sites of the N -glycosylation motifs. In one of the strains, a novel glycosylation site was created near a deleted glycosylation site. The affected glycosylation sites were predominantly clustered in regions of gp120 that are not involved in the direct interaction with either CD4, CCR5, CXCR4, or gp41. The mutant viruses containing the deleted glycosylation sites were markedly more infectious in CEM T-cell cultures than wild-type virus.
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Molecular cloning and characterization of multiple isoforms of the snowdrop (Galanthus nivalis L.) lectin.
Planta, 1991Co-Authors: E. J. M. Van Damme, N De Clercq, Frank Claessens, K Hemschoote, Benjamin Peeters, Willy J PeumansAbstract:Screening of a copy-DNA (cDNA) library constructed from RNA isolated from young developing ovaries of snowdrop (Galanthus nivalis) resulted in the isolation of five lectin clones which clearly differed from each other with regard to their nucleotide sequence and deduced amino-acid sequence. Sequence comparison between the coding regions of different lectin cDNAs revealed the highest homology between lectin clones LECGNA 3 and LECGNA 5, showing 96.4% and 93.6% similarity at the nucleotide level and at the deduced amino-acid level, respectively, whereas lectin clones LECGNA 1 and LECGNA 3 showed the lowest homology of 81.6% and 68.6% for the nucleotide sequence and the amino-acid sequence, respectively. Only very few lectin cDNA clones containing a polyadenylated tail could be isolated. Moreover all these cDNA clones were derived from isolectin 3 and showed some variability within the length of the 3' untranslated region. The major transcription initiation site was located 30 bases upstream from the AUG codon as could be deduced from primer-extension analysis. Taking into account the small 5' untranslated region of the lectin clones, the size of the lectin mRNA, which is approx. 780 nucleotides as determined by Northern blot analysis, is in good agreement with the length of the cDNA clones isolated. Besides the ovary tissue, both the leaf and the flower tissue were also shown to express the lectin mRNA in a flowering snowdrop plant.
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Biosynthesis, primary structure and molecular cloning of snowdrop (Galanthus nivalis L.) lectin
FEBS Journal, 1991Co-Authors: Els J. M. Van Damme, Irwin J. Goldstein, Hanae Kaku, Fulvio Perini, Ben Peeters, Fumio Yagi, B. Decock, Willy J PeumansAbstract:Poly(A)-rich RNA isolated from ripening ovaries of snowdrop (Galanthus nivalis L.) yielded a single 17-kDa lectin polypeptide upon translation in a wheat-germ cell-free system. This lectin was purified by affinity chromatography. Translation of the same RNA in Xenopus leavis oocytes revealed a lectin polypeptide which was about 2 kDa smaller than the in vitro synthesized precursor, suggesting that the oocyte system had removed a 2-kDa signal peptide. A second post-translational processing step was likely to be involved since both the in vivo precursor and the Xenopus translation products were about 2 kDa larger than the mature lectin polypeptide. This hypothesis was confirmed by the structural analysis of the amino acid sequence of the mature protein and the cloned mRNA. Edman degradation and carboxypeptidase Y digestion of the mature protein, and structural analysis of the peptides obtained after chemical cleavage and modification, allowed determination of the complete 10.5 amino acid sequence of the snowdrop lectin polypeptide. Comparison of this sequence with the deduced amino acid sequence of a lectin cDNA clone revealed that besides the mature lectin polypeptide, the lectin mRNA also encoded a 23 amino acid signal-sequence and a C-terminal extension of 29 amino acids. which confirms the results from in vitro translation experiments.
