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Biomedical subjects

P Rougé

Publications and source records attributed to P Rougé.

At least 19 recordsLinked to original sources
PubMed2006

The lipid transfer proteins (LTP) essentially concentrate in the skin of Rosaceae fruits as cell surface exposed allergens.

The localization and distribution of non-specific lipid transfer proteins (nsLTP) allergens in the skin and pulp of Rosaceae fruits (apple, peach, apricot, plum) has been investigated. nsLTP essentially concentrate in the pericarp of the fruits whereas the pulp contains lower amounts of allergens. Immunolocalization showed they are primarily located in the cytosol but are subsequently excreted and finally accumulate at the plasmalemma-cell wall interface and in the cell wall. However, high discrepancies were observed in the content of allergens among, e.g. different cultivars of apple. As a consequence, the consumption of peeled-off fruits is recommended to reduce the risk of severe allergic reactions (anaphylactic shock) in individuals sensitized to Rosaceae fruits.

Allergens↗
PubMed2005

Desalination of mixed tannery effluent with membrane bioreactor and reverse osmosis treatment.

A limiting factor for the reuse and recycling of treated tannery wastewater for irrigation and other uses is the high salt content, which persists even after conventional treatment. Reverse osmosis (RO) membrane treatment has been shown to significantly reduce the salt contents of tannery effluents. However, the high organic content of tannery effluent leads to rapid scaling and biofouling of RO membranes with a consequent reduction in flux rates and performance. Membrane bioreactors (MBR) have been shown to be highly effective in the removal of organic pollutants and suspended solids from tannery effluent. This research investigated the use of a combined MBR and RO treatment process to treat tannery effluents to an acceptable level for irrigation purposes. The MBR was operated at 17-20 h retention time, at a F/M ratio of 0.52 kg COD x kg SS(-1) x day(-1) and a volumetric loading rate of 3.28 kg COD x m(-3) x day(-1). This treatment reduced the COD, BOD, and ammonia concentrations of the effluent by 90-100%. The MBR was shown to be an excellent pretreatment prior to RO technology, due to the high removal efficiency of organic compounds and suspended solids, with average concentrations of 344 mg x L(-1) COD and 20 mg x L(-1) BOD achieved in the permeate. RO treatment reduced the salt content of the MBR permeate by up to 97.1%. The results of the research demonstrated that the MBR system developed was appropriate for the treatment of tannery effluents and, in combination with the RO treatment, reduced the salt content to acceptable levels for irrigation. The MBR pretreatment reduced bio-fouling and scaling of subsequent RO treatment and improved the overall performance of the RO unit. It is believed that this is the first investigation of a combined MBR and RO treatment for tannery effluents. This research provided data for an outline design of a full-scale MBR and RO plant with a treatment capacity of 5000 m3 per day for mixed tannery effluents.

Bioreactors↗
PubMed2002

Structure of an RNase-related protein from Calystegia sepium.

The structure of a catalytically inactive RNase-related protein from Calystegia sepium (CalsepRRP) has been resolved by protein crystallography at a resolution of 2.05 A and an R factor of 20.74%. Although the protein is completely devoid of ribonuclease activity, it adopts the typical alpha + beta structure of non-base-specific RNases. Analysis of the structure revealed that two amino-acid substitutions in the 'active' P1 site, in combination with the less hydrophobic/aromatic character of the B1 base-recognition site and a completely disrupted B2 base-recognition site, might account for this complete lack of activity.

Amino Acid Sequence↗
PubMed2001

Structure of a legume lectin from the bark of Robinia pseudoacacia and its complex with N-acetylgalactosamine.

The structure of the bark lectin RPbAI (isoform A4) from Robinia pseudoacacia has been determined by protein crystallography both in the free form and complexed with N-acetylgalactosamine. The free form is refined at 1.80 A resolution to an R-factor of 18.9% whereas the complexed structure has an R-factor of 19.7% at 2.05 A resolution. Both structures are compared to each other and to other available legume lectin structures. The polypeptide chains of the two structures exhibit the characteristic legume lectin tertiary fold. The quaternary structure resembles that of the Phaseolus vulgaris lectin, the soybean agglutinin, and the Dolichos biflorus lectin, but displays some unique features leading to the extreme stability of this lectin.

Acacia↗
PubMed2001

The Gal/GalNAc-specific lectin from the plant pathogenic basidiomycete Rhizoctonia solani is a member of the ricin-B family.

The lectin isolated from the phytopathogenic basidiomycete Rhizoctonia solani (RSA) is a homodimer of two noncovalently associated monomers of 15.5 kDa. RSA is a basic protein (pI > 9) which consists mainly of beta-sheets. A presumed relationship with ricin-B is supported by the sequence similarity between the N-terminus of RSA and the N-terminal subdomain of ricin-B. Hydrophobic cluster analysis confirms that the N-terminus of both proteins has a comparable folding. RSA exhibits specificity towards Gal/GalNAc whereby the hydroxyls at the C3', C4', and C6' positions of the pyranose ring play a key role in the interaction with simple sugars. The carbohydrate-binding site of RSA apparently accommodates only a single sugar unit. Our results demonstrate an obvious evolutionary relationship between some fungal and plant lectins, but also provide evidence for the occurrence of a lectin consisting of subunits corresponding to a single subdomain of ricin-B.

Acetylgalactosamine↗
PubMed2001

Classification of plant lectins in families of structurally and evolutionary related proteins.

The majority of plant lectins can be classified in seven families of structurally and evolutionary related proteins. Within a given lectin family most but not necessarily all members are built up of protomers with a similar primary structure and overall 3-D fold. The overall structure of the native lectins is not only determined by the structure of the protomers but depends also on the degree of oligomerization and in some cases on the post-translational processing of the lectin precursors. In general, lectin families are fairly homogeneous for what concerns the overall specificity of the individual lectins, which illustrates that the 3-D structure of the binding site has been conserved during evolution. In the case of the jacalin-related lectins the occurrence of a mannose- and galactose-binding subfamily can be explained by the fact that a post-translational cleavage of the protomers (of the galactose-binding subfamily) yields a slightly altered binding site. Unlike the other families, the legume lectins display a wide range of specificites, which is clearly reflected in the occurrence of sugar-binding sites with a different 3-D structure.

Carbohydrate Metabolism↗
PubMed2001

Mannose-binding plant lectins: different structural scaffolds for a common sugar-recognition process.

Mannose-specific lectins are widely distributed in higher plants and are believed to play a role in recognition of high-mannose type glycans of foreign micro-organisms or plant predators. Structural studies have demonstrated that the mannose-binding specificity of lectins is mediated by distinct structural scaffolds. The mannose/glucose-specific legume (e.g., Con A, pea lectin) exhibit the canonical twelve-stranded beta-sandwich structure. In contrast to legume lectins that interact with both mannose and glucose, the monocot mannose-binding lectins (e.g., the Galanthus nivalis agglutinin or GNA from bulbs) react exclusively with mannose and mannose-containing N-glycans. These lectins possess a beta-prism structure. More recently, an increasing number of mannose-specific lectins structurally related to jacalin (e.g., the lectins from the Jerusalem artichoke, banana or rice), which also exhibit a beta-prism organization, were characterized. Jacalin itself was re-defined as a polyspecific lectin which, in addition to galactose, also interacts with mannose and mannose-containing glycans. Finally the B-chain of the type II RIP of iris, which has the same beta-prism structure as all other members of the ricin-B family, interacts specifically with mannose and galactose. This structural diversity associated with the specific recognition of high-mannose type glycans highlights the importance of mannose-specific lectins as recognition molecules in higher plants.

Binding Sites↗
PubMed2001

Purification, characterization, immunolocalization and structural analysis of the abundant cytoplasmic beta-amylase from Calystegia sepium (hedge bindweed) rhizomes.

An abundant catalytically active beta-amylase (EC 3.2.1.2) was isolated from resting rhizomes of hedge bindweed (Calystegia sepium). Biochemical analysis of the purified protein, molecular modeling, and cloning of the corresponding gene indicated that this enzyme resembles previously characterized plant beta-amylases with regard to its amino-acid sequence, molecular structure and catalytic activities. Immunolocalization demonstrated that the beta-amylase is exclusively located in the cytoplasm. It is suggested that the hedge bindweed rhizome beta-amylase is a cytoplasmic vegetative storage protein.

Amino Acid Sequence↗
PubMed2001

Iris bulbs express type 1 and type 2 ribosome-inactivating proteins with unusual properties.

Two closely related lectins from bulbs of the Dutch iris (Iris hollandica var. Professor Blaauw) have been isolated and cloned. Both lectins, called Iris agglutinin b and Iris agglutinin r, possess N-glycosidase activity and share a high sequence similarity with previously described type 2 ribosome-inactivating proteins (RIP). However, these lectins show only 57% to 59% sequence identity to a previously characterized type 1 RIP from iris, called IRIP. The identification of the iris lectins as type 2 RIP provides unequivocal evidence for the simultaneous occurrence of type 1 and type 2 RIP in iris bulbs and allowed a detailed comparison of type 1 and type 2 RIP from a single plant, which provides further insight into the molecular evolution of RIP. Binding studies and docking experiments revealed that the lectins exhibit binding activity not only toward Gal/N-acetylgalactosamine, but also toward mannose, demonstrating for the first time that RIP-binding sites can accommodate mannose.

Amino Acid Sequence↗
PubMed2000

Microenvironment of cysteine 242 in type-1 ribosome-inactivating protein from iris.

IRIP is a type-1 ribosome-inactivating protein isolated from the bulbs of Iris hollandica. It is one of the few type-1 RIPs that contain Cys residue(s) in their primary sequence. IRIP contains a single Cys residue at position 242. Although IRIP is thought to be a monomeric protein, SDS-PAGE indicates that part of the IRIP molecules can exist as disulphide bridge-linked dimers. Probing of the reactivity of the unique Cys residue by 5, 5'-dithiobis(2-nitrobenzoic acid) indicates that Cys(242) in IRIP is free but is only partially accessible to modifiers. Molecular modelling of IRIP is in agreement with this conclusion. Binding of the ligands adenine and poly(A) results in little or no effect on the conformation of Cys(242) in IRIP. Chemical modification of IRIP by a specific thiol modifier does not abolish the RNA N-glycosidase activity of IRIP, suggesting that Cys(242) is not critical for the enzymatic activity of IRIP. These results suggest that IRIP has the potential to be developed as a novel immunotoxin.

Amino Acid Sequence↗
PubMed2000

Crystal structures of human pancreatic alpha-amylase in complex with carbohydrate and proteinaceous inhibitors.

Crystal structures of human pancreatic alpha-amylase (HPA) in complex with naturally occurring inhibitors have been solved. The tetrasaccharide acarbose and a pseudo-pentasaccharide of the trestatin family produced identical continuous electron densities corresponding to a pentasaccharide species, spanning the -3 to +2 subsites of the enzyme, presumably resulting from transglycosylation. Binding of the acarviosine core linked to a glucose residue at subsites -1 to +2 appears to be a critical part of the interaction process between alpha-amylases and trestatin-derived inhibitors. Two crystal forms, obtained at different values of pH, for the complex of HPA with the protein inhibitor from Phaseolus vulgaris (alpha-amylase inhibitor) have been solved. The flexible loop typical of the mammalian alpha-amylases was shown to exist in two different conformations, suggesting that loop closure is pH-sensitive. Structural information is provided for the important inhibitor residue, Arg-74, which has not been observed previously in structural analyses.

Acarbose↗
PubMed2000

Fruit-specific lectins from banana and plantain.

One of the predominant proteins in the pulp of ripe bananas (Musa acuminata L.) and plantains (Musa spp.) has been identified as a lectin. The banana and plantain agglutinins (called BanLec and PlanLec, respectively) were purified in reasonable quantities using a novel isolation procedure, which prevented adsorption of the lectins onto insoluble endogenous polysaccharides. Both BanLec and PlanLec are dimeric proteins composed of two identical subunits of 15 kDa. They readily agglutinate rabbit erythrocytes and exhibit specificity towards mannose. Molecular cloning revealed that BanLec has sequence similarity to previously described lectins of the family of jacalin-related lectins, and according to molecular modelling studies has the same overall fold and three-dimensional structure. The identification of BanLec and PlanLec demonstrates the occurrence of jacalin-related lectins in monocot species, suggesting that these lectins are more widespread among higher plants than is actually believed. The banana and plantain lectins are also the first documented examples of jacalin-related lectins, which are abundantly present in the pulp of mature fruits but are apparently absent from other tissues. However, after treatment of intact plants with methyl jasmonate, BanLec is also clearly induced in leaves. The banana lectin is a powerful murine T-cell mitogen. The relevance of the mitogenicity of the banana lectin is discussed in terms of both the physiological role of the lectin and the impact on food safety.

Amino Acid Sequence↗
PubMed2000

Purification and structural analysis of an abundant thaumatin-like protein from ripe banana fruit.

The pulp of ripe bananas (Musa acuminata) contains an abundant thaumatin-like protein (TLP). Characterization of the protein and molecular cloning of the corresponding gene from banana demonstrated that the native protein consists of a single polypeptide chain of 200 amino acid residues. Molecular modelling further revealed that the banana thaumatin-like protein (Ban-TLP) adopts an overall fold similar to that of thaumatin and thaumatin-like PR-5 proteins. Although the banana protein exhibits an electrostatically polarized surface, which is believed to be essential for the antifungal properties of TLPs, it is apparently devoid of antifungal activity towards pathogenic fungi. It exhibits a low but detectable in vitro endo-beta-1,3-glucanase (EC 3.2.1.x) activity. As well as being present in fruits, Ban-TLP also occurs in root tips where its accumulation is enhanced by methyl jasmonate treatment of plants. Pulp of plantains (Musa acuminata) also contains a very similar TLP, which is even more abundant than its banana homologue. Our results demonstrate for the first time that fruit-specific (abundant) TLPs are not confined to dicots but occur also in fruits of monocot species. The possible role of the apparent widespread accumulation of fruit-specific TLPs is discussed.

Amino Acid Sequence↗
PubMed2000

Isolation and characterization of a jacalin-related mannose-binding lectin from salt-stressed rice (Oryza sativa) plants.

A novel plant lectin was isolated from salt-stressed rice (Oryza sativa L.) plants and partially characterized. The lectin occurs as a natural mixture of two closely related isoforms consisting of two identical non-covalently linked subunits of 15 kDa. Both isoforms are best inhibited by mannose and exhibit potent mitogenic activity towards T-lymphocytes. Biochemical analyses and sequence comparisons further revealed that the rice lectins belong to the subgroup of mannose-binding jacalin-related lectins. In addition, it could be demonstrated that the lectins described here correspond to the protein products of previously described salt-stress-induced genes. Our results not only identify the rice lectin as a stress protein but also highlight the possible importance of protein-carbohydrate interactions in stress responses in plants.

Amino Acid Sequence↗
PubMed2000

Purification, characterization and structural analysis of an abundant beta-1,3-glucanase from banana fruit.

An abundant, catalytically active beta-1,3-endoglucanase (EC 3.2.1. 39) has been isolated from the pulp of ripe bananas. Biochemical analysis of the purified protein, molecular modelling, and molecular cloning of the corresponding gene indicate that this banana enzyme closely resembles previously characterized plant beta-glucanases with respect to its amino-acid sequence, structure and biological activity. The results described in this paper demonstrate both the occurrence of an abundant active beta-1,3-endoglucanases in fruits and also readdress the question of the possible involvement of these enzymes in the ripening and/or softening process.

Amino Acid Sequence↗
PubMed2000

Characterization and molecular cloning of two different type 2 ribosome-inactivating proteins from the monocotyledonous plant Polygonatum multiflorum.

Leaves of the monocotyledonous plant Polygonatum multiflorum L. (Solomon's seal) contain besides a monocot mannose-binding lectin two galactose/N-acetylgalactosamine (Gal/GalNAc)-binding type 2 ribosome-inactivating proteins (RIPs). Both RIPs were purified using a combination of classical protein purification techniques and affinity chromatography. Although both RIPs consist of protomers of 65 kDa, the P. multiflorum RIP monomer (PMRIPm) occurs as a monomer of approximately 60 kDa, whereas the tetramer (PMRIPt) is a tetramer of 240 kDa. Both RIPs exhibit similar RNA N-glycosidase activity but differ in their specific agglutination activity and carbohydrate-binding specificity, PMRIPt being a GalNAc-specific lectin whereas PMRIPm is Gal/GalNAc-specific. Toxicity tests indicated that both Polygonatum RIPs exhibit a very low cytotoxicity towards human and animal cells. Analysis of the genomic clones encoding both RIPs revealed a high degree of sequence similarity to other type 2 RIPs. Molecular modelling confirmed that both Polygonatum RIPs have a similar structure to ricin.

Amino Acid Sequence↗