3c9z | pdb_00003c9z
Sambucus nigra agglutinin II (SNA-II), tetragonal crystal form
Structural highlights
Function[NIGB_SAMNI] Non-toxic type 2 RIP which strongly inhibits mammalian protein synthesis but does not affect plant nor bacterial protein synthesis. The A chain is responsible for inhibiting protein synthesis through the catalytic inactivation of 60S ribosomal subunits by removing adenine from position 4,324 of 28S rRNA. The B chain is a galactose-specific lectin that facilitates the binding of nigrin b to the cell membrane that precedes endocytosis. Publication Abstract from PubMedBark of elderberry (Sambucus nigra) contains a galactose (Gal)/N-acetylgalactosamine (GalNAc)-specific lectin (SNA-II) corresponding to slightly truncated B-chains of a genuine Type-II ribosome-inactivating protein (Type-II RIPs, SNA-V), found in the same species. The three-dimensional X-ray structure of SNA-II has been determined in two distinct crystal forms, hexagonal and tetragonal, at 1.90 A and 1.35 A, respectively. In both crystal forms, the SNA-II molecule folds into two linked betabeta-trefoil domains, with an overall conformation similar to that of the B-chains of ricin and other Type-II RIPs. Glycosylation is observed at four sites along the polypeptide chain, accounting for 14 saccharide units. The high-resolution structures of SNA-II in complex with Gal and five Gal-related saccharides (GalNAc, lactose, alphaalpha1-methylgalactose, fucose, and the carcinoma-specific Tn antigen) were determined at 1.55 A resolution or better. Binding is observed in two saccharide-binding sites for most of the sugars: a conserved aspartate residue interacts simultaneously with the O3 and O4 atoms of saccharides. In one of the binding sites, additional interactions with the protein involve the O6 atom. Analytical gel filtration, small angle X-ray scattering studies and crystal packing analysis indicate that, although some oligomeric species are present, the monomeric species predominate in solution. Proteins 2008. (c) 2008 Wiley-Liss, Inc. Structural basis for sugar recognition, including the Tn carcinoma antigen, by the lectin SNA-II from Sambucus nigra.,Maveyraud L, Niwa H, Guillet V, Svergun DI, Konarev PV, Palmer RA, Peumans WJ, Rouge P, Van Damme EJ, Reynolds CD, Mourey L Proteins. 2008 Sep 17. PMID:18798567[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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