DC-SIGN binds to HIV-1 glycoprotein 120 in a distinct but overlapping fashion compared with ICAM-2 and ICAM-3

J Biol Chem. 2004 Apr 30;279(18):19122-32. doi: 10.1074/jbc.M400184200. Epub 2004 Feb 16.

Abstract

DC-SIGN is a C-type lectin that binds to endogenous adhesion molecules ICAM-2 and ICAM-3 as well as the viral envelope glycoprotein human immunodeficiency virus, type 1, glycoprotein (gp) 120. We wished to determine whether DC-SIGN binds differently to its endogenous ligands ICAM-2 and ICAM-3 versus HIV-1 gp120. We found that recombinant soluble DC-SIGN bound to gp120-Fc more than 100- and 50-fold better than ICAM-2-Fc and ICAM-3-Fc, respectively. This relative difference was maintained using DC-SIGN expressed on three different CD4-negative cell lines. Although the cell surface affinity for gp120 varied by up to 4-fold on the cell lines examined, the affinity for gp120 was not a correlate of the ability of the cell line to transfer virus. Monosaccharides with equatorial 4-OH groups competed as well as D-mannose for gp120 binding to DC-SIGN, regardless of how the other hydroxyl groups were positioned. Disaccharide competitors and glycan chip analysis showed that DC-SIGN has a preference for oligosaccharides linked in an alpha-anomeric configuration. Alanine-scanning mutagenesis of DC-SIGN revealed that highly conserved residues that coordinate calcium (Asp-366) and/or are involved in both calcium and specific carbohydrate interactions (Glu-347, Asn-349, Glu-354, and Asp-355) significantly compromised binding to all three ligands. Mutating non-conserved residues (Asn-311, Arg-345, Val-351, Gly-352, Glu-353, Ser-360, Gly-361, and Asn-362) minimally affected binding except for the Asp-367 mutant, which enhanced gp120 binding but diminished ICAM-2 and ICAM-3 binding. Conversely, mutating the moderately conserved residue (Gly-346) abrogated gp120 binding but enhanced ICAM-2 and ICAM-3 binding. Thus, DC-SIGN appears to bind in a distinct but overlapping manner to gp120 when compared with ICAM-2 and ICAM-3.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigens, CD / metabolism
  • Binding Sites
  • Binding, Competitive
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cell Membrane / metabolism
  • HIV Envelope Protein gp120 / metabolism*
  • Humans
  • Lectins, C-Type / genetics
  • Lectins, C-Type / metabolism*
  • Ligands
  • Mutagenesis, Site-Directed
  • Oligosaccharides / chemistry
  • Oligosaccharides / metabolism
  • Polysaccharides / metabolism
  • Protein Array Analysis
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • Antigens, CD
  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • HIV Envelope Protein gp120
  • ICAM2 protein, human
  • ICAM3 protein, human
  • Lectins, C-Type
  • Ligands
  • Oligosaccharides
  • Polysaccharides
  • Receptors, Cell Surface
  • Recombinant Proteins