The conserved arginine residue in all siglecs is essential for Siglec-7 binding to sialic acid

Siglecs are sialic acid (Sia)-binding immunoglobulin-like lectins; the majority of Siglecs functions as transmembrane receptors on the immune cells via Sia residues. Recently, a new Sia binding site in Siglec-7, termed site 2, where arginine (R) 67 was critical, was identified by computational model...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2021-01, Vol.534, p.1069-1075
Main Authors: Yoshimura, Atsushi, Hatanaka, Rina, Tanaka, Hiroshi, Kitajima, Ken, Sato, Chihiro
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Antigens, Differentiation, Myelomonocytic - chemistry
Antigens, Differentiation, Myelomonocytic - metabolism
Binding Sites
Conserved Sequence
Humans
Immune receptor
Innate immunity
K562 Cells
Lectins - chemistry
Lectins - metabolism
Mice
Molecular Docking Simulation
Protein Binding
Sialic acid
Sialic Acids - metabolism
Siglec
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Summary:Siglecs are sialic acid (Sia)-binding immunoglobulin-like lectins; the majority of Siglecs functions as transmembrane receptors on the immune cells via Sia residues. Recently, a new Sia binding site in Siglec-7, termed site 2, where arginine (R) 67 was critical, was identified by computational modeling and biochemical analyses, relative to the primary Sia binding site, termed site 1, containing critical R124. Here, the presence of a new essential R94 residue, which is completely conserved among all identified Siglecs, was demonstrated. A mutation of R94 residue in Siglec-7 led to the disappearance of the Sia binding property, similar to a site 1 mutation (R124A). R94 is close to R67 in site 2, and site 2 mutations at either of them abolished the ligand-binding properties to both gangliosides and glycoproteins. These data suggest that, in addition to site 1, the conserved R residue among Siglecs in site 2 is another functional site. •The recently found second sialic acid binding site of Siglec-7 is not well understood.•R94 residue completely conserved in all Siglecs is found in the second binding site.•R94 residue is essential for the sialic acid binding activity of Siglec-7.•Siglec-7 binds to sialic acid residues in proteins, but not in lipids, in K562 cell.
ISSN:0006-291X
1090-2104
DOI:10.1016/j.bbrc.2020.10.023