Grahn Elin, Askarieh Glareh, Holmner Asa, Tateno Hiroaki, Winter Harry C, Goldstein Irwin J, Krengel Ute
Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
J Mol Biol. 2007 Jun 8;369(3):710-21. doi: 10.1016/j.jmb.2007.03.016. Epub 2007 Mar 15.
MOA, a lectin from the mushroom Marasmius oreades, is one of the few reagents that specifically agglutinate blood group B erythrocytes. Further, it is the only lectin known to have exclusive specificity for Galalpha(1,3)Gal-containing sugar epitopes, which are antigens that pose a severe barrier to animal-to-human organ transplantation. We describe here the structure of MOA at 2.4 A resolution, in complex with the linear trisaccharide Galalpha(1,3)Galbeta(1,4)GlcNAc. The structure is dimeric, with two distinct domains per protomer: the N-terminal lectin module adopts a ricinB/beta-trefoil fold and contains three putative carbohydrate-binding sites, while the C-terminal domain serves as a dimerization interface. This latter domain, which has an unknown function, reveals a novel fold with intriguing conservation of an active site cleft. A number of indications suggest that MOA may have an enzymatic function in addition to the sugar-binding properties.
MOA是一种从硬柄小皮伞蘑菇中提取的凝集素，是少数能特异性凝集B型血红细胞的试剂之一。此外，它是已知唯一对含Galα(1,3)Gal糖表位具有专一特异性的凝集素，这些糖表位是动物到人类器官移植的严重障碍。我们在此描述了分辨率为2.4埃的MOA与线性三糖Galα(1,3)Galβ(1,4)GlcNAc复合物的结构。该结构为二聚体，每个原体有两个不同的结构域：N端凝集素模块采用蓖麻毒素B/β-三叶折叠结构，包含三个假定的碳水化合物结合位点，而C端结构域作为二聚化界面。后一个结构域功能未知，揭示了一种具有有趣的活性位点裂缝保守性的新折叠结构。一些迹象表明，MOA除了具有糖结合特性外，可能还具有酶功能。
