scholarly journals The structure of siglec-7 in complex with sialosides: leads for rational structure-based inhibitor design

2006 ◽  
Vol 397 (2) ◽  
pp. 271-278 ◽  
Author(s):  
Helen Attrill ◽  
Hirokazu Takazawa ◽  
Simone Witt ◽  
Soerge Kelm ◽  
Rainer Isecke ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Binding Sites ◽  
Cellular Interactions ◽  
Inhibitor Design ◽  
Binding Assays ◽  
Rational Structure ◽  
Transmembrane Receptors ◽  
Acetylneuraminic Acid ◽  
Sialic Acid Binding ◽  
Inhibition Data

Siglecs (sialic acid binding Ig-like lectins) are transmembrane receptors for sialylated glycoconjugates that modulate cellular interactions and signalling events in the haematopoietic, immune and nervous systems. Siglec-7 is a structural prototype for the recently described family of immune inhibitory CD33-related siglecs and is predominantly expressed on natural killer cells and monocytes, as well as subsets of CD8 T-cells. Siglec-specific inhibitors are desired for the detection of masked and unmasked forms of siglecs, to aid in dissection of signalling pathways and as tools to investigate siglecs as potential therapeutic targets. As a first step towards this end, we present the crystal structure of siglec-7 in complex with a sialylated ligand, the ganglioside analogue DSLc4 [α(2,3)/α(2,6) disialyl lactotetraosyl 2-(trimethylsilyl)ethyl], which allows for a detailed description of the binding site, required for structure-guided inhibitor design. Mutagenesis and binding assays were used to demonstrate a key structural role for Lys131, a residue that changes conformation upon sialic acid binding. Differences between the binding sites of siglec family members were then exploited using α-methyl Neu5Ac (N-acetylneuraminic acid) as a basic scaffold. A co-crystal of siglec-7 in complex with the sialoside inhibitor, oxamido-Neu5Ac [methyl α-9-(amino-oxalyl-amino)-9-deoxy-Neu5Ac] and inhibition data for the sialosides gives clear leads for future inhibitor design.

Interaction of Mycoplasma gallisepticum with sialyl glycoproteins

1980 ◽  
Vol 30 (2) ◽  
pp. 353-361
Author(s):  
L R Glasgow ◽  
R L Hill
Keyword(s):  
Sialic Acid ◽  
Mycoplasma Gallisepticum ◽  
Binding Assays ◽  
Molecular Weights ◽  
Acetylneuraminic Acid ◽  
Direct Binding ◽  
Membrane Bound ◽  
Strict Specificity ◽  
Human Glycophorin ◽  
Acid Structure

The binding of several glycoproteins to freshly grown and harvested cells of Mycoplasma gallisepticum was examined. Only human glycophorin, the major sialoglycoprotein of the erythrocyte membrane, bound tightly as judged by direct binding assays with 125I-labeled glycoproteins. Neuraminidase-treated glycophorin did not bind, suggesting that binding is mediated through sialic acid groups. Although other sialoglycoproteins did not appear to bind M. gallisepticum by direct binding assays, some inhibited the binding of glycophorin. The best inhibitors had a mucin-like structure, with high molecular weights and high sialic acid contents. N-acetylneuraminic acid appeared to be the favored sialic acid structure for binding, but there was no strict specificity for its anomeric linkage. Neuraminidase activity could not be detected on the surface of M. gallisepticum, suggesting that this enzyme is not involved in the mechanism of adherence of sialoglycoproteins. Binding of sialoglycoproteins was time dependent, however, and markedly diminished with increasing ionic strength, but was largely unaffected between pH 4 and 9.

Adhesion of Pseudomonas aeruginosa to human buccal epithelial cells: evidence for two classes of receptors

1985 ◽  
Vol 31 (6) ◽  
pp. 563-569 ◽  
Author(s):  
David W. McEachran ◽  
Randall T. Irvin
Keyword(s):  
Binding Sites ◽  
Copy Number ◽  
Alginic Acid ◽  
High Copy Number ◽  
Acetylneuraminic Acid ◽  
High Affinity ◽  
Buccal Epithelial Cells ◽  
Low Copy Number ◽  
Inhibition Data ◽  
Number Class

The adhesion of Pseudomonas aeruginosa strain 492c to trypsinized and untrypsinized buccal epithelial cells (BECs) was studied. Kinetic analysis of the adhesion data, employing a Langmuir absorption isotherm, indicated the presence of two classes of binding sites on untrypsinized BECs: a high affinity – low copy number site (apparent association constant (Ka ≈ 1.57 × 10−8 mL/cell with ca. 29 binding sites/cell) and a low affinity – high copy number class of binding sites (Ka ≈ 4.78 × 10−10 mL/cell with ca. 264 binding sites/cell). The low affinity – high copy number class of sites was found to be trypsin sensitive. A single class of binding sites was found on trypsinized BECs exhibiting a high affinity – low copy number (Ka ≈ 3.70 × 10−7 mL/cell with ca. 31 binding sites/cell). Positive cooperativity in binding of P. aeruginosa strain 492c to the low affinity – high copy number class site on untrypsinized BECs was demonstrated by analysis of Hill plots of the adhesion data. Sugar inhibition data using a preincubation methodology showed an inhibition of adhesion to trypsinized BECs in the presence of N-acetylneuraminic acid and D-arabinose, while these same two sugars enhanced adhesion to untrypsinized BECs. D-Galactose and N-acetylglucosamine enhanced adhesion to both types of BECs though the latter did to different extents. D-Fucose only inhibited adhesion to untrypsinized BECs. Without preincubation the sugar inhibition data indicated that N-acetylglucosamine had no effect on adhesion while N-acetylneuraminic acid and D-fucose both enhanced adhesion to both types of BECs. D-Arabinose had a slight inhibitory effect on adhesion, while D-galactose had a slight enhancing effect to both cell types, but to different levels. This sugar data suggests a difference in the receptors on the two types of BECs, but the possibility of metabolism of these sugars by P. aeruginosa requires one to interpret this data with caution. Flagella were shown not to be involved in adhesion, while the alginic acid of the capsule was implicated. The low copy number binding site is speculated to be a pili-binding site, while the high copy number class of binding sites is proposed to involve a lectin which binds alginic acid.

scholarly journals Specificity and Affinity of Sialic Acid Binding by the Rhesus Rotavirus VP8* Core

2002 ◽  
Vol 76 (20) ◽  
pp. 10512-10517 ◽  
Author(s):  
Philip R. Dormitzer ◽  
Zhen-Yu J. Sun ◽  
Ola Blixt ◽  
James C. Paulson ◽  
Gerhard Wagner ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Attachment ◽  
Resonance Spectroscopy ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Lower Affinity ◽  
Initial Cell ◽  
Acetylneuraminic Acid ◽  
Sialic Acid Binding ◽  
Broad Specificity

ABSTRACT Nuclear magnetic resonance spectroscopy demonstrates that the rhesus rotavirus hemagglutinin specifically binds α-anomeric N-acetylneuraminic acid with a Kd of 1.2 mM. The hemagglutinin requires no additional carbohydrate moieties for binding, does not distinguish 3′ from 6′ sialyllactose, and has approximately tenfold lower affinity for N-glycolylneuraminic than for N-acetylneuraminic acid. The broad specificity and low affinity of sialic acid binding by the rotavirus hemagglutinin are consistent with this interaction mediating initial cell attachment prior to the interactions that determine host range and cell type specificity.

scholarly journals Screening coronavirus and human proteins for sialic acid binding sites using a docking approach

2021 ◽  
Vol 8 (3) ◽  
pp. 248-263
Author(s):  
Chia-Wen Wang ◽  
◽  
Oscar K. Lee ◽  
Wolfgang B. Fischer ◽  
Keyword(s):  
Sialic Acid ◽  
Binding Sites ◽  
Sialic Acid Binding ◽  
Docking Approach ◽  
Human Proteins

scholarly journals A Novel Sialic Acid Binding Site on Factor H Mediates Serum Resistance of Sialylated Neisseria gonorrhoeae

1998 ◽  
Vol 187 (5) ◽  
pp. 743-752 ◽  
Author(s):  
Sanjay Ram ◽  
Ajay K. Sharma ◽  
Scott D. Simpson ◽  
Sunita Gulati ◽  
Daniel P. McQuillen ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Neisseria Gonorrhoeae ◽  
Factor H ◽  
Serum Resistance ◽  
Complement Pathway ◽  
Fourfold Increase ◽  
Acetylneuraminic Acid ◽  
Binding Domains ◽  
Sialic Acid Binding ◽  
Serum Killing

Factor H (fH), a key alternative complement pathway regulator, is a cofactor for factor I–mediated cleavage of C3b. fH consists of 20 short consensus repeat (SCR) domains. Sialic acid binding domains have previously been localized to fH SCRs 6–10 and 13. To examine fH binding on a sialylated microbial surface, we grew Neisseria gonorrhoeae in the presence of 5′-cytidinemonophospho-N-acetylneuraminic acid, which sialylates lipooligosaccharide and converts to serum resistance gonococci previously sensitive to nonimmune serum killing. fH domains necessary for binding sialylated gonococci were determined by incubating organisms with recombinant human fH (rH) and nine mutant rH molecules (deletions spanning the entire fH molecule). rH and all mutant rH molecules that contained SCRs 16–20 bound to the sialylated strain; no mutant molecule bound to serum-sensitive nonsialylated organisms. Sialic acid was demonstrated to be the fH target by flow cytometry that showed a fourfold increase in fH binding that was reversed by neuraminidase-mediated cleavage of sialic acid off gonococci. Functional specificity of fH was confirmed by decreased total C3 binding and almost complete conversion to iC3b on sialylated gonococci. Sialic acid can therefore bind fH uniquely through SCRs 16–20. This blocks complement pathway activation for N. gonorrhoeae at the level of C3.

scholarly journals Assessment of Sialic Acid Diversity in Cancer- and Non-Cancer Related CA125 Antigen Using Sialic Acid-Binding Ig-Like Lectins (Siglecs)

2012 ◽  
Vol 32 (3) ◽  
pp. 187-194 ◽  
Author(s):  
N. Mitic ◽  
B. Milutinovic ◽  
M. Jankovic
Keyword(s):  
Sialic Acid ◽  
Ovarian Carcinoma ◽  
Solid Phase ◽  
Tumour Marker ◽  
Sialic Acids ◽  
Binding Assays ◽  
Ovarian Carcinoma Cell Line ◽  
Sialic Acid Binding ◽  
Solid Phase Binding ◽  
Different Origin

This study was aimed at obtaining insight into the diversity of sialic acids in cancer- and non-cancer-related CA125 antigen, tumour marker of serous ovarian cancer. Starting from available data suggesting the possible relevance of sialic acids for discriminating CA125 antigens of different origin, we have employed a new experimental approach based on the use of human sialic acid-binding Ig-like lectins, Siglecs, as tools for the investigation of sialylation.Siglec−2, belonging to the group of evolutionarily conserved Siglecs, and Siglec−3, −6, −7, −9 and −10, which are CD33-like Siglecs, were probed in solid-phase binding assays with cancer-related CA125 antigens from pleural fluid of patients with ovarian carcinoma (pfCA125), the OVCAR-3 ovarian carcinoma cell line (clCA125) and a non-cancer-related CA125 antigen, i.e. pregnancy-associated pCA125 antigen.All Siglecs used showed detectable binding to pCA125 antigen. Siglec−3, Siglec−7 and Siglec−2 exhibited moderately stronger binding to pCA125 antigen than the others. In contrast to this, Siglec−2 and Siglec−3 preferentially recognized pfCA125 with greater total binding than for pCA125, whereas Siglec−9 and Siglec−10 were highly selective for clCA125.Siglecs promise to be powerful tools for discriminating CA125 of different origin and could propagate further research on other molecular markers of biomedical and diagnostic importance.

scholarly journals Physiochemical studies on achatininH, a novel sialic acid-binding lectin

1989 ◽  
Vol 257 (1) ◽  
pp. 65-71 ◽  
Author(s):  
C Mandal ◽  
S Basu ◽  
C Mandal
Keyword(s):  
Sialic Acid ◽  
Binding Affinity ◽  
Physicochemical Characterization ◽  
Alpha Helix ◽  
Spectral Studies ◽  
Acetylneuraminic Acid ◽  
High Affinity ◽  
Sugar Binding ◽  
Sialic Acid Binding ◽  
Binding Lectin

We have purified a sialic acid-binding lectin, achatininH, in a single step by affinity chromatography, having high affinity for 9-O-acetylneuraminic acid. The physicochemical characterization of the interaction of achatininH with bivalent metal ions and sialic acid derivatives by the use of spectrofluorimetry, spectropolarimetry and precipitin reaction is reported. From fluorescence quenching studies the binding of Ca2+ (Ka = 251 +/- 9 M-1) and of Mn2+ (Ka = 86 +/- 5 M-1) was found to be weak, but their presence is absolutely necessary for sugar binding as well as biological activity. The nature and position of the substituent group play a very important role in the binding affinity. AchatininH shows a high affinity for 9-O-acetylneuraminic acid (Ka = 1.20 x 10(3) +/- 0.07 x 10(3) M-1) compared with that for the 4-O-acetyl derivative. In oligomers the binding strength increases in the order monosaccharide less than disaccharide less than trisaccharide. The binding affinity of achatininH for the disaccharide was found to reach a peak around pH 8. From c.d. spectral studies achatininH was found to have a high beta-sheet content (46%) and a low alpha-helix content (24%). From precipitin analysis at least one sugar-binding site on each of the 16 monomer subunits of the protein is indicated.

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