Marilynn E. Etzler

Symbol Nomenclature for Graphical Representations of Glycans

Author(s): Varki, Ajit; Cummings, Richard D; Aebi, Markus; Packer, Nicole H; Seeberger, Peter H; Esko, Jeffrey D; Stanley, Pamela; Hart, Gerald; Darvill, Alan; Kinoshita, Taroh; Prestegard, James J; Schnaar, Ronald L; Freeze, Hudson H; Marth, Jamey D; Bertozzi, Carolyn R; Etzler, Marilynn E; Frank, Martin; Vliegenthart, Johannes Fg; Lutteke, Thomas; Perez, Serge; Bolton, Evan; Rudd, Pauline; Paulson, James; Kanehisa, Minoru; Toukach, Philip; Aoki-Kinoshita, Kiyoko F; Dell, Anne; Narimatsu, Hisashi; York, William; Taniguchi, Naoyuki; Kornfeld, Stuart

Symbol nomenclature for glycan representation

The glycan symbol nomenclature proposed by Harvey et al. in these pages has relative advantages and disadvantages. The use of symbols to depict glycans originated from Kornfeld in 1978, was systematized in the First Edition of “Essentials of Glycobiology” and updated for the second edition, with input from relevant organizations such as the Consortium for Functional Glycomics. We also note that >200 illustrations in the second edition have already been published using our nomenclature and are available for download at PubMed.

Subunit structure of wheat germ agglutinin.

Summary Wheat germ agglutinin was found to have a molecular weight of 36,200 ± 5% at pH 7.2 by high-speed sedimentation equilibrium. At this pH, the protein had a sedimentation coefficient of 3.5 S. These data indicate that the native agglutinin consists of dimers of the 18,000-dalton subunits observed upon sodium dodecyl sulfate polyacrylamide gel electrophoresis. Agglutinin treated with 0.05 N HCl, in which it sedimented at 2.1 S, and then dialyzed back to pH 7.2 sedimented as the native protein, suggesting reversible denaturation of the protein or dissociation of subunits.

Carbohydrate binding activity of a lectin-like glycoprotein from stems and leaves of Dolichosbiflorus

Abstract A glycoprotein from the stems and leaves of the Dolichos biflorus plant that cross reacts with antibodies to the seed lectin has been found to bind to affinity columns of blood group A + H substance covalently linked to Sepharose. This binding of the cross reactive material to the affinity resin differs from that of the seed lectin in that it is easily dissociated with 0.15 M NaCl. Affinity electrophoresis using entrapped blood group A + H substance shows that the carbohydrate binding activity of the cross reactive material is weakly inhibited with N-acetyl-D -galactosamine and N-acetyl-D -glucosamine. Glucose, mannose and galactose gave no inhibition when tested at concentrations of 50 mM. These data indicate that the specificity of the cross reactive material is somewhat different from the N-acetyl-D -galactosamine specificity of the seed lectin. The significance of these findings is discussed in relation to the structural similarities of the cross reactive material and the seed lectin.

Molecular modelling of theDolichos biflorus seed lectin and its specific interactions with carbohydrates: α-D-N-acetyl-galactosamine, Forssman disaccharide and blood group A trisaccharide

The three-dimensional structure ofDolichos biflorus seed lectin has been constructed using five legume lectins for which high resolution crystal structures were available. The validity of the resulting model has been thoroughly investigated. Final structure optimization was conducted for the lectin complexed with αGalNAc, providing thereby the first three-dimensional structure of lectin/GalNAc complex. The role of theN-acetyl group was clearly evidenced by the occurrence of a strong hydrogen bond between the protein and the carbonyl oxygen of the carbohydrate and by hydrophobic interaction between the methyl group and aromatic amino acids. Since the lectin specificity is maximum for the Forssman disaccharide αGalNAc(1–3)βGalNAc-O-Me and the blood group A trisaccharide αGalNAc(1–3)[αFuc(1–2)]βGal-O-Me, the complexes with these oligosaccharides have been also modelled.

Isolation and characterization of a lectin from the roots of Dolichos biflorus

A lectin has been isolated from the roots of 7-day-old Dolichos biflorus plants and has been compared with the D. biflorus seed lectin. The root lectin differs from the seed lectin in molecular weight, subunit stoichiometry, amino acid composition, amino terminal amino acid sequence, and isoelectric focusing pattern. However, the root lectin has in common with the seed lectin a specificity for N-acetyl-D-galactosamine, and upon denaturation the root lectin will react weakly with antiserum made to denatured seed lectin. Distribution studies of this lectin in germinating seedlings show that the highest levels of lectin are found in 1-day-old roots. Upon dissection and analysis of 7-day-old roots, the highest levels of the lectin are in the uppermost segment. In addition, isoforms of this lectin also exist in the stems and leaves of the plant.

NH2-terminal sequences of the subunits of Dolichos biflorus lectin.

The seeds of the Dolichos bijlorus plant contain a lectin that has a specificity for terminal nonreducing a-N-acetyl-D-galactosamine residues [1,2] . This lectin is a glycoprotein of approx. 110 000 mol. wt and exists in several molecular forms that appear to differ from one another only by slight differences in carbohydrate composition [3]. The predominant form of the lectin is a tetramer composed of two types of subunits, I and II, with mol. wt 27 700 and 27 300, respectively [4]. These subunits have similar amino acid and carbohydrate compositions, show reactions of identity when tested in immunodiffusion against antisera made to either subunit, and have alanine as their NH*-terminal amino acid [4] . Treatment of the isolated subunits with carboxypeptidase A showed that subunit I has valine or leucine at its COOH-terminal whereas the COOH terminal of subunit II is not cleaved by the enzyme [4]. The above data suggest that subunits I and II may differ from one another only at their COOH-terminal ends and that the NH*-terminal portions of the subunits may be identical. This hypothesis is supported by the finding that the NH*-terminal fragments of the subunits, isolated after CNBr treatment of the lectin, have the same electrophoretic mobility whereas the COOH-terminal fragments have different mobilities [5] . In the present paper we report the NHs-terminal sequences of the first thirty residues of subunits I and II. The identity of these sequences confirms the identity of the NH*-terminal portions of the subunits. The sequences also show some homologies with NHs-terminal sequences of other lectins.

Metal chelate affinity chromatography of the Dolichos biflorus seed lectin and its subunits

Metal chelate affinity chromatography was first introduced by Porath and coworkers in 1975 [I]. This method is based on the principle that a protein capable of binding divalent cations may interact with these ions immobilized on chelate gels. Agarose gels containingiminodiacetic acid, a &elate formingligand, have been used to fractionate human serum proteins [l], isolate lactoferrin from human milk [2], purify (r2-SH glycoprotein [3], interferon [4,5], granule proteins from granulocytes [6] and a,-macroglobulin [7]. In all these reports Cu2+ or Zn2+ were chelated to the agarose gel used in the purification procedures. The Dolichos bijlorus seed lectin, which consists of apparently equal amounts of 2 types of subunits (&II) [8] has been shown to bind -4 Ca2+/native tetrameric molecule [9]. However the distribution of these ions between the subunits is unknown. Here, we report the binding properties of the native lectin as well as its isolated subunits to a Ca2+ containing affinity column.

Oligosaccharide signaling of plant cells

A variety of oligosaccharide signals have been identified that function in the regulation of plant development, defense, and other interactions of plants with the environment. Some of these oligosaccharides are produced by various pathogens or symbionts, whereas others are synthesized by the plant itself. This mini‐review summarizes our present state of information on these oligosaccharide signals and provides an overview of approaches being used to identify receptors for these signals and gain an understanding of the mechanism(s) by which these signals activate downstream events. Possible biotechnological applications of future work in this field are also considered. J. Cell. Biochem. Suppls. 30/31:123–128, 1998.

A Structural comparison of the subunits of the Dolichos biflorus seed lectin by peptide mapping and carboxyl terminal amino acid analysis

Abstract The Dolichos biflorus seed lectin is a 110,000 Mr tetrameric glycoprotein composed of equal amounts of two structurally similar subunits, I and II. Cleavage of the lectin with Staphylococcus aureus V-8 protease followed by sodium dodecyl sulfate-urea poly-acrylamide gel electrophoresis produces a peptide map consisting of at least six peptide bands. A comparison of the peptide maps from isolated Subunits I and II shows that all the peptides are common to both subunits with the exception of one. This unique peptide has been isolated and appears to be derived from the carboxyl terminus of the subunit since cyanogen bromide treatment generates a fragment with the same electrophoretic mobility as the carboxyl-terminal cyanogen bromide fragment of the lectin. Carboxypeptidase Y treatment of Subunit I resulted in the rapid release of leucine, followed by serine and valine. Similar treatment of Subunit II resulted in the initial release of aspartate, followed by leucine and proline. These data support earlier work which indicated that the two subunits differ in structure at their carboxyl terminal ends. The significance of this finding in regard to the relationship between the structure and function of the lectin is discussed.