DC-SIGN Neck Domain Is a pH-sensor Controlling Oligomerization

Abstract

DC-SIGN is a C-type lectin receptor of dendritic cells and is involved in the early stages of numerous infectious diseases. DC-SIGN is organized into a tetramer enabling multivalent interaction with pathogens. Once formed, the DC-SIGN-pathogen complex can be internalized into compartments of increasing acidity. We have studied the pH dependence of the oligomerization state and conformation of the entire extracellular domain and neck region. We present evidence for equilibrium between the monomeric and tetrameric states of the extracellular domain, which exhibits a marked dependence with respect to both pH and ionic strength. Using solution x-ray scattering we have obtained a molecular envelope of the extracellular domain in which a model has been built. Our results highlight the central role of the neck domain in the pH-sensitive control of the oligomerization state, in the extended conformation of the protein, and in carbohydrate recognition domain organization and presentation. This work opens new insight into the molecular mechanism of ligand release and points to new avenues to block the first step of this important infection pathway.

Compact, Polyvalent Mannose Quantum Dots as Sensitive, Ratiometric FRET Probes for Multivalent Protein–Ligand Interactions

“…Based on their distinct QD‐binding properties, we propose that the CRDs are facing upwardly along the coiled‐coil axes in DC‐SIGN (hence readily accessible to multivalent binding to the QD), but sideways in DC‐SIGNR (hence unavailable to bind the QD multivalently, Figure 4). Such structural models agree well with those proposed from small‐angle X‐ray scattering studies 13. The different CRD arrangement and accessibility in DC‐SIGN/R may account for their distinct viral binding/transmission properties.…”

Synthesis and Characterization of Linker‐Armed Fucose‐Based Glycomimetics

“…Most likely, the amplification observed occur through statistical rebinding [19] because, with a distance of 35 to 38 Å in the DC-SIGN tetramer, the dendrimer is too small to bridge two binding sites. [20] Compound 21 was the most effective DC-SIGN blocker in the tested series, with an IC 50 value of 39 μm.…”

“…DC-SIGN ECD protein (residues 66-404) was overexpressed and purified as described previously. [20] Surface Plasmon Resonance: SPR experiments were performed with a Biacore 3000 at 25°C using a CM4 chip. During functionalization steps, HBS-P running buffer was used at 5 μL/min flow rate.…”

Glycodendritic structures: tools to interact with DC-SIGN

“…It is a type II trans-membrane C-type lectin with a single C-terminal Carbohydrate Recognition Domain (CRD). In the cellular membrane, DC-SIGN is assembled as a tetramer, due to an extended coiled-coil region that allows simultaneous presentation of four CRDs Feinberg et al, 2005;Serrano-Sierra-Gomez et al, 2008;Tabarani et al, 2009).…”