An official website of the United States government
Enhanced Concanavalin A Binding to Preorganized Mannose Nanoarrays in Glycodendrimersomes Revealed Multivalent Interactions
Abstract The effect of the two‐dimensional glycan display on glycan‐lectin recognition remains poorly understood despite the importance of these interactions in a plethora of cellular processes, in (patho)physiology, as well as its potential for advanced therapeutics. Faced with this challenge we utilized glycodendrimersomes, a type of synthetic vesicles whose membrane mimics the surface of a cell and offers a means to probe the carbohydrate biological activity. These single‐component vesicles were formed by the self‐assembly of sequence‐defined mannose‐Janus dendrimers, which serve as surrogates for glycolipids. Using atomic force microscopy and molecular modeling we demonstrated that even mannose, a monosaccharide, was capable of organizing the sugar moieties into periodic nanoarrays without the need of the formation of liquid‐ordered phases as assumed necessary for rafts. Kinetics studies of Concanavalin A binding revealed that those nanoarrays resulted in a new effective ligand yielding a ten‐fold increase in the kinetic and thermodynamic constant of association.
more »
« less
- Award ID(s):
- 1807127
- PAR ID:
- 10237105
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 60
- Issue:
- 15
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 8352-8360
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract We report a novel glycan array architecture that binds the mannose‐specific glycan binding protein, concanavalin A (ConA), with sub‐femtomolar avidity. A new radical photopolymerization developed specifically for this application combines the grafted‐from thiol–(meth)acrylate polymerization with thiol–ene chemistry to graft glycans to the growing polymer brushes. The propagation of the brushes was studied by carrying out this grafted‐to/grafted‐from radical photopolymerization (GTGFRP) at >400 different conditions using hypersurface photolithography, a printing strategy that substantially accelerates reaction discovery and optimization on surfaces. The effect of brush height and the grafting density of mannosides on the binding of ConA to the brushes was studied systematically, and we found that multivalent and cooperative binding account for the unprecedented sensitivity of the GTGFRP brushes. This study further demonstrates the ease with which new chemistry can be tailored for an application as a result of the advantages of hypersurface photolithography.more » « less
-
Abstract We report a novel glycan array architecture that binds the mannose‐specific glycan binding protein, concanavalin A (ConA), with sub‐femtomolar avidity. A new radical photopolymerization developed specifically for this application combines the grafted‐from thiol–(meth)acrylate polymerization with thiol–ene chemistry to graft glycans to the growing polymer brushes. The propagation of the brushes was studied by carrying out this grafted‐to/grafted‐from radical photopolymerization (GTGFRP) at >400 different conditions using hypersurface photolithography, a printing strategy that substantially accelerates reaction discovery and optimization on surfaces. The effect of brush height and the grafting density of mannosides on the binding of ConA to the brushes was studied systematically, and we found that multivalent and cooperative binding account for the unprecedented sensitivity of the GTGFRP brushes. This study further demonstrates the ease with which new chemistry can be tailored for an application as a result of the advantages of hypersurface photolithography.more » « less
-
Kirchhoff, Frank (Ed.)ABSTRACT HIV-1 has eluded vaccine therapy for the past 40 years. The virus mutates rapidly and is protected by a shifting glycan shield of mannose sugars, which has hindered the broad neutralization of the virus by antibodies (Abs). Studies have shown that mannose residues are self-adhesive, but it is not known if these adhesions drive HIV-1 to aggregate in solution, further complicating Ab neutralization. The behavior of HIV-1 in culture media was monitored using Dynamic Light Scattering and complementary atomic force microscopy (AFM) imaging in the presence of anti-gp120 Abs, lectins, mannosidase, and mucin. After accounting for the serum contribution from the culture media, HIV-1 was found to be diffusing in solution in 400–700 nm clusters. These clusters could be sheared into single virus particles by filtration, but the dispersed particles clustered back within a short time frame. Sample preparation prior to AFM and transmission electron microscopy (TEM) imaging appears to disperse clusters, but the clusters become visible in AFM when they are stabilized by Abs in solution. The clustered form of the virus appears to restrict access of Abs, lectins, and glycosidases to surfaces within the cluster. Mannosidase treatment following virus dispersion by filtration prevented clustering, suggesting that the mannose glycan shield is involved in cluster formation. Dispersed HIV-1 particles that were bound by Abs did not re-cluster back. Free mucin molecules (porcine gastric mucin) effectively dispersed HIV-1 clusters, even those stabilized by Abs. HIV-1-loaded mucin dried on the AFM surface with a fern-like fractal pattern, similar to that seen clinically in cervical mucin during the more penetrable ovulation stage. IMPORTANCEThe phenomenon of reversible clustering is expected to further nuance HIV immune stealth because virus surfaces can escape interaction with antibodies (Abs) by hiding temporarily within clusters. It is well known that mucin reduces HIV virulence, and the current perspective is that mucin aggregates HIV-1 to reduce infections. Our findings, however, suggest that mucin is dispersing HIV clusters. The study proposes a new paradigm for how HIV-1 may broadly evade Ab recognition with reversible clustering and why mucin effectively neutralizes HIV-1.more » « less
-
Bisected N -glycans represent a unique class of protein N -glycans that play critical roles in many biological processes. Herein, we describe the systematic synthesis of these structures. A bisected N -glycan hexasaccharide was chemically assembled with two orthogonal protecting groups attached at the C2 of the branching mannose residues, followed by sequential installation of GlcNAc and LacNAc building blocks to afford two asymmetric bisecting “cores”. Subsequent enzymatic modular extension of the “cores” yielded a comprehensive library of biantennary N -glycans containing the bisecting GlcNAc and presenting 6 common glycan determinants in a combinatorial fashion. These bisected N -glycans and their non-bisected counterparts were used to construct a distinctive glycan microarray to study their recognition by a wide variety of glycan-binding proteins (GBPs), including plant lectins, animal lectins, and influenza A virus hemagglutinins. Significantly, the bisecting GlcNAc could bestow (PHA-L, rDCIR2), enhance (PHA-E), or abolish (ConA, GNL, anti-CD15s antibody, etc. ) N -glycan recognition of specific GBPs, and is tolerated by many others. In summary, synthesized compounds and the unique glycan microarray provide ideal standards and tools for glycoanalysis and functional glycomic studies. The microarray data provide new information regarding the fine details of N -glycan recognition by GBPs, and in turn improve their applications.more » « less
