A novel mechanism for LSECtin binding to Ebola virus surface glycoprotein through truncated glycans.
LSECtin is a member of the C-type lectin family of glycan-binding receptors that is expressed on sinusoidal endothelial cells of the liver and lymph nodes. To compare the sugar and pathogen binding properties of LSECtin with those of related but more extensively characterized receptors, such as DC-SIGN, a soluble fragment of LSECtin consisting of the C-terminal carbohydrate-recognition domain has been expressed in bacteria. A biotin-tagged version of the protein was also generated and complexed with streptavidin to create tetramers. These forms of the carbohydrate-recognition domain were used to probe a glycan array and to characterize binding to oligosaccharide and glycoprotein ligands. LSECtin binds with high selectivity to glycoproteins terminating in GlcNAcbeta1-2Man. The inhibition constant for this disaccharide is 3.5 microm, making it one of the best low molecular weight ligands known for any C-type lectin. As a result of the selective binding of this disaccharide unit, the receptor recognizes glycoproteins with a truncated complex and hybrid N-linked glycans on glycoproteins. Glycan analysis of the surface glycoprotein of Ebola virus reveals the presence of such truncated glycans, explaining the ability of LSECtin to facilitate infection by Ebola virus. High mannose glycans are also present on the viral glycoprotein, which explains why DC-SIGN also binds to this virus. Thus, multiple receptors interact with surface glycoproteins of enveloped viruses that bear different types of relatively poorly processed glycans.
Powlesland
Alex S
AS
Division of Molecular Biosciences, Imperial College, London SW7 2AZ, United Kingdom.
Fisch
Tanja
T
Institute of Virology and Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, 91054 Erlangen, Germany.
Taylor
Maureen E
ME
Division of Molecular Biosciences, Imperial College, London SW7 2AZ, United Kingdom.
Smith
David F
DF
Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322.
Tissot
Bérangère
B
Division of Molecular Biosciences, Imperial College, London SW7 2AZ, United Kingdom.
Dell
Anne
A
Division of Molecular Biosciences, Imperial College, London SW7 2AZ, United Kingdom.
Pöhlmann
Stefan
S
Institute of Virology and Nikolaus-Fiebiger-Center for Molecular Medicine, University Erlangen-Nürnberg, 91054 Erlangen, Germany; Institute of Virology, Hannover Medical School, 30625 Hannover, Germany.
Drickamer
Kurt
K
Division of Molecular Biosciences, Imperial College, London SW7 2AZ, United Kingdom. Electronic address: k.drickamer@imperial.ac.uk.
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D029043:Ebolavirus / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011522:Protons; D051381:Rats; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
C505228:CLEC4G protein, human; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D011134:Polysaccharides; D011522:Protons; D014764:Viral Proteins