Interaction of five -mannose-specific lectins with a series of synthetic branched trisaccharides

The interaction of a series of synthetic, branched trisaccharides with five -mannose-specific lectins was studied by precipitation-inhibition assay. The branched methyl [alpha]--mannotrioside, [alpha]--Manp-(1-->3)-[[alpha]--Manp-(1-->6)-[alpha]--ManpOMe, the best inhibitor of the Con A--Dextran interaction, was 42 times more potent than [alpha]--ManpOMe, and 3-6 times more potent than the two trisaccharides substituted with -glucosyl groups, and 8-15 times those with -galactosyl groups. Surprisingly, methyl O-[alpha]--mannopyranosyl-(1-->3)-[alpha]--mannopyranoside was bound to Con A 8-fold more avidly than methyl [alpha]--mannopyranoside. However, the related pea lectin (PSA) was singularly different from Con A in its carbohydrate-binding activity, showing no significantly enhanced binding to any of the sugars examined. The trisaccharides containing terminal, nonreducing, (1-->3)-linked [alpha]--mannopyranosyl groups, i.e., [alpha]--Manp-(1-->3)-[[alpha]--Glcp-(1-->6)-[alpha]--ManpOMe, [alpha]--Manp-(1-->3)-][alpha]--Galp-(1-->6)]-[alpha]--ManpOMe, and [alpha]--Manp-(1-->3)-[[alpha]--Manp-(1-->6)]-[alpha]-- ManpOMe, were the best inhibitors of the snowdrop lectin (GNA)--mannan precipitation system. On the other hand, all branched trisaccharides exhibited very similar inhibitory potencies toward the daffodil lectin (NPA)--mannan interaction, whereas [alpha]--Manp-(1-->3)-[[alpha]--Galp-(1-->6)]-[alpha]--ManpOMe and [alpha]--Manp-(1-->3)-[[alpha]--Manp-(1-->6)]-[alpha]--ManpOMe were somewhat better inhibitors than the other branched trisaccharides of the amaryllis lectin (HHA)--mannan precipitation reaction. Of the oligosaccharides studied, the linear trisaccharide [alpha]--Manp-(1-->6)-[alpha]--Manp-(1-->6)--Man appears to be the most complementary to the combining site(s) of NPA and HHA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29275/1/0000334.pd

Isolation and characterization of a second lectin (SNA-II) present in elderberry (Sambucus nigra L.) bark

A second lectin (SNA-II) has been isolated from elderberry (Sambucus nigra L.) bark by affinity chromatography on immobilized asialo-glycophorin. This lectin is a blood group nonspecific glycoprotein containing 7.8% carbohydrate and which is rich in asparagine/aspartic acid, glutamine/glutamic acid, glycine, valine, and leucine. Gel filtration on Superose 12 gave a single symmetrical peak corresponding to Mr, 51,000; SDS-acrylamide electrophoresis gave a single polypeptide, Mr, 30,000. Hence SNA-II appears to be a homodimer. The lectin is a Gal/GalNAc-specific lectin which is precipitated by glycoproteins containing GalNAc-terminated oligosaccharide chains (e.g., asialo-ovine submaxillary and hog gastric mucins), and by glycoproteins and polysaccharides having multiple terminal nonreducing -galactosyl groups as occur in asialoglycophorin, asialo-laminin and Type 14 pneumococcal polysaccharide. The carbohydrate binding specificity of SNA-II was studied by sugar hapten inhibition of the asialo-glycophorin precipitation reaction. The lectin's binding site appears to be most complementary to GalNAc linked [alpha] to the C-2, C-3, or C-6 hydroxyl group of galactose. These disaccharide units are approximately 100 times more potent than melibiose, 60 times more potent than N-acetyllactosamine, and 30 times more potent than lactose. Interestingly, the blood group A-active trisaccharide containing an -fucosyl group linked [alpha]1-2 to galactose was 10-fold poorer as an inhibitor than the parent oligosaccharide (GalNAc[alpha]1-3Gal), suggesting steric hindrance to binding by the [alpha]--fucosyl group; this explains the failure of the lectin to exhibit blood group A specificity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28711/1/0000532.pd

S18.20 Preparation of two kinds of sialic acid specific monomeric monovalent lectin derivatives and their application to the study of cell surface glycoconjugates by flow cytometry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45649/1/10719_2005_Article_BF01210154.pd

Biosynthesis, primary structure and molecular cloning of snowdrop ( Galanthus nivalis L.) lectin

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65530/1/j.1432-1033.1991.tb16339.x.pd

Identification of glycosylation genes and glycosylated amino acids of flagellin in Pseudomonas syringae pv. tabaci

A glycosylation island is a genetic region required for glycosylation. The glycosylation island of flagellin in Pseudomonas syringae pv. tabaci 6605 consists of three orfs: orf1, orf2 and orf3. Orf1 and orf2 encode putative glycosyltransferases, and their deletion mutants, Delta orf1 and Delta orf2, exhibit deficient flagellin glycosylation or produce partially glycosylated flagellin respectively. Digestion of glycosylated flagellin from wild-type bacteria and non-glycosylated flagellin from Delta orf1 mutant using aspartic N-peptidase and subsequent HPLC analysis revealed candidate glycosylated amino acids. By generation of site-directed Ser/Ala-substituted mutants, all glycosylated amino acid residues were identified at positions 143, 164, 176, 183, 193 and 201. Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) analysis revealed that each glycan was about 540 Da. While all glycosylation-defective mutants retained swimming ability, swarming ability was reduced in the Delta orf1, Delta orf2 and Ser/Ala-substituted mutants. All glycosylation mutants were also found to be impaired in the ability to adhere to a polystyrene surface and in the ability to cause disease in tobacco. Based on the predicted tertiary structure of flagellin, S176 and S183 are expected to be located on most external surface of the flagellum. Thus the effect of Ala-substitution of these serines is stronger than that of other serines. These results suggest that glycosylation of flagellin in P. syringae pv. tabaci 6605 is required for bacterial virulence. It is also possible that glycosylation of flagellin may mask elicitor function of flagellin molecule

Plant immunity and symbiosis signaling mediated by LysM receptors

Plants possess the ability to recognize microbe-associated molecular patterns (MAMPs) and PAMPs through the PRRs, and initiate pattern-triggered immunity. MAMPs are derived from cell-envelope components, secreted materials and cytosolic proteins from bacteria, oomycetes or fungi, and some MAMPs play a similar function in the innate immunity in mammals. Chitin is a representative fungal MAMP and triggers defense signaling in a wide range of plant species. The chitin receptors CEBiP and CERK1 on the plasma membrane have LysM (lysin motif) in their ectodomains. These molecules play an important role for the defense responses in rice and Arabidopsis, strictly recognizing the size and acetylated form of chitin oligosaccharides. However, related LysM receptors also play major roles for the signaling in root nodule and arbuscular mycorrhizal symbiosis. This review summarizes current knowledge on the molecular mechanisms of the defense and symbiosis signaling mediated by LysM receptors, including the activation steps of chitin-induced defense signaling downstream of LysM receptors