scholarly journals Trans-sialylation: a strategy used to incorporate sialic acid into oligosaccharides

2021 ◽  
Author(s):  
Rosa M. de Lederkremer ◽  
M. Eugenia Giorgi ◽  
Rosalia Agusti
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Crucial Role ◽  
Synthetic Methods ◽  
Cell Surface Glycoconjugates

Sialic acid, as component of cell surface glycoconjugates, plays a crucial role in recognition events. Efficient synthetic methods are necessary for the supply of sialosides in enough quantities for biochemical...

scholarly journals Exo-enzymatic addition of diazirine-modified sialic acid to cell surfaces enables photocrosslinking of glycoproteins

2021 ◽  
Author(s):  
Nageswari Yarravarapu ◽  
Rohit Sai Reddy Konada ◽  
Narek Darabedian ◽  
Nichole J. Pedowtiz ◽  
Soumya N. Krishnamurthy ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Cell Types ◽  
Cell Surfaces ◽  
Binding Interactions ◽  
Multiple Cell ◽  
Labeling Method ◽  
Cell Surface Glycoconjugates

Glycan binding often mediates extracellular macromolecular recognition events. Accurate characterization of these binding interactions can be difficult because of dissociation and scrambling that occur during purification and analysis steps. Use of photocrosslinking methods has been pursued to covalently capture glycan-dependent interactions in situ however use of metabolic glycan engineering methods to incorporate photocrosslinking sugar analogs is limited to certain cell types. Here we report an exo-enzymatic labeling method to add a diazirine-modified sialic acid (SiaDAz) to cell surface glycoconjugates. The method involves chemoenzymatic synthesis of diazirine-modified CMP-sialic acid (CMP-SiaDAz), followed by sialyltransferase-catalyzed addition of SiaDAz to desialylated cell surfaces. Cell surface SiaDAz-ylation is compatible with multiple cell types and is facilitated by endogenous extracellular sialyltransferase activity present in Daudi B cells. This method for extracellular addition of α2-6-linked SiaDAz enables UV-induced crosslinking of CD22, demonstrating the utility for covalent capture of glycan-mediated binding interactions.

scholarly journals BAK1 Is Not a Target of the Pseudomonas syringae Effector AvrPto

2011 ◽  
Vol 24 (1) ◽  
pp. 100-107 ◽  
Author(s):  
Tingting Xiang ◽  
Na Zong ◽  
Jie Zhang ◽  
Jinfeng Chen ◽  
Mingsheng Chen ◽  
...  
Keyword(s):  
Cell Surface ◽  
Immune Responses ◽  
Pseudomonas Syringae ◽  
Plant Cell ◽  
Crucial Role ◽  
Pathogenic Bacteria ◽  
Effector Proteins ◽  
Receptor Like Kinase ◽  
Receptor Kinases ◽  
New Evidence

Plant cell surface-localized receptor kinases such as FLS2, EFR, and CERK1 play a crucial role in detecting invading pathogenic bacteria. Upon stimulation by bacterium-derived ligands, FLS2 and EFR interact with BAK1, a receptor-like kinase, to activate immune responses. A number of Pseudomonas syringae effector proteins are known to block immune responses mediated by these receptors. Previous reports suggested that both FLS2 and BAK1 could be targeted by the P. syringae effector AvrPto to inhibit plant defenses. Here, we provide new evidence further supporting that FLS2 but not BAK1 is targeted by AvrPto in plants. The AvrPto-FLS2 interaction prevented the phosphorylation of BIK1, a downstream component of the FLS2 pathway.

Target cell surface glycoconjugates and neural induction in an amphibian

Development ◽  
1985 ◽  
Vol 86 (1) ◽  
pp. 39-51
Author(s):  
Lydie Gualandris ◽  
Pierre Rouge ◽  
Anne-Marie Duprat
Keyword(s):  
Cell Surface ◽  
Binding Sites ◽  
Neural Induction ◽  
Specific Receptor ◽  
Con A ◽  
Neural Signal ◽  
Electrophysiological Properties ◽  
Ionic Fluxes ◽  
Target Membrane ◽  
Cell Surface Glycoconjugates

The possible involvement of target membrane specific receptor(s) in the transmission of the neural signal leading to activation of the intracellular machinery involved in the process of neural determination, has been examined using lectin probes (Con A, succinylated-ConA, LcA, PsA and SBA). Not only Con A binding sites but many different glycoconjugated molecules (α-Dgalactose, N-acetyl-D-galactosamine, α-D-fucose, N-acetyl-D-glucosamine, etc.) would have to be involved, if neural receptor(s) are invoked to explain initiation of neural induction. We show here that the close involvement of such receptor molecules in neural induction is so far hypothetical and remains to be demonstrated. Moreover we are inclined to the view of Barth and others who suggested that ionic fluxes and physicochemical and electrophysiological properties of the target membrane could play a crucial role in neural induction.

scholarly journals Sialic acid-Dependent Binding and Viral Entry of SARS-CoV-2

2021 ◽  
Author(s):  
Linh Nguyen ◽  
Kelli McCord ◽  
Duong Bui ◽  
Kim Bouwman ◽  
Elena Kitova ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Receptor Binding ◽  
Viral Entry ◽  
Receptor Binding Domain ◽  
Artificial Membrane ◽  
Neuraminidase Treatment ◽  
S Protein ◽  
Knock Out

Abstract Emerging evidence suggests that host glycans influence infection by SARS-CoV-2. Here, we reveal that the receptor-binding domain (RBD) of the spike (S)-protein on SARS-CoV-2 recognizes oligosaccharides containing sialic acid (SA), with preference for the oligosaccharide of monosialylated gangliosides. Gangliosides embedded within an artificial membrane also bind the RBD. The monomeric affinities (Kd = 100-200 μM) of gangliosides for the RBD are similar to heparan sulfate, another negatively charged glycan ligand of the RBD proposed as a viral co-receptor. RBD binding and infection of SARS-CoV-2 pseudotyped lentivirus to ACE2-expressing cells is decreased upon depleting cell surface SA level using three approaches: sialyltransferase inhibition, genetic knock-out of SA biosynthesis, or neuraminidase treatment. These effects on RBD binding and pseudotyped viral entry are recapitulated with pharmacological or genetic disruption of glycolipid biosynthesis. Together, these results suggest that sialylated glycans, specifically glycolipids, facilitate viral entry of SARS-CoV-2.

scholarly journals Multiple evolutionary origins reflect the importance of sialic acid transporters in the colonisation potential of bacterial pathogens and commensals

2021 ◽  
Author(s):  
Emmanuele Severi ◽  
Michelle Rudden ◽  
Andrew Bell ◽  
Tracy Palmer ◽  
Nathalie Juge ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Sialic Acid ◽  
Classification Scheme ◽  
Sialic Acids ◽  
Evolutionary Selection ◽  
Evolutionary Origins ◽  
Mucosal Surfaces ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
Cell Surface Glycoconjugates

AbstractLocated at the tip of cell surface glycoconjugates, sialic acids are at the forefront of host-microbe interactions and, being easily liberated by sialidase enzymes, are used as metabolites by numerous bacteria, particularly by pathogens and commensals living on or near diverse mucosal surfaces. These bacteria rely on specific transporters for the acquisition of host-derived sialic acids. Here, we present the first comprehensive genomic and phylogenetic analysis of bacterial sialic acid transporters, leading to the identification of multiple new families and subfamilies. Our phylogenetic analysis suggests that sialic acid-specific transport has evolved independently at least 8 times during the evolution of bacteria, from within 4 of the major families/superfamilies of bacterial transporters, and we propose a robust classification scheme to bring together a myriad of different nomenclatures that exist to date. The new transporters discovered occur in diverse bacteria including Spirochaetes, Bacteroidetes, Planctomycetes, and Verrucomicrobia, many of which are species that have not been previously recognised to have sialometabolic capacities. Two subfamilies of transporters stand out in being fused to the sialic acid mutarotase enzyme, NanM, and these transporter fusions are enriched in bacteria present in gut microbial communities. We also provide evidence for a possible function of a sialic acid transporter component in chemotaxis that is independent of transport. Our analysis supports the increasing experimental evidence that competition for host-derived sialic acid is a key phenotype for successful colonisation of complex mucosal microbiomes, such that a strong evolutionary selection has occurred for the emergence of sialic acid specificity within existing transporter architectures.

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